FR3047858A1 - METHOD FOR AUTOMATICALLY ADJUSTING A TUNABLE ADJUSTMENT CIRCUIT, AND AUTOMATIC TUNING SYSTEM USING THE SAME - Google Patents

Abstract

The invention relates to a method for automatically adjusting a tunable matching circuit with single input access and single output access, for example a tunable matching circuit with single input access and single output port coupled to an antenna. a radio transceiver. The invention also relates to an automatic tuning system using this method. An automatic tuning system comprises: a "user access" (5); a "target access" (6); a detection unit (1); a tunable matching circuit having a single input port and a single output port (7) having one or more adjustable impedance devices; a signal processing unit (2) which outputs a tuning instruction as a function of one or more temperature signals and as a function of at least two actual quantities dependent on an impedance seen by the target access; and a tuning control unit (3) which delivers one or more tuning control signals, the reactance of each of the adjustable impedance devices of the tunable tuning circuit being determined by at least one of one or more tuning signals. chord control.

Description

Method for automatically adjusting a tunable tuning circuit, and automatic tuning system using this method

TECHNICAL FIELD OF THE INVENTION The invention relates to a method for automatically adjusting a tunable adaptation circuit with single input access and single output access, for example a tunable matching circuit with single input access single output coupled to an antenna of a radio transceiver. The invention also relates to an automatic tuning system using this method.

STATE OF THE PRIOR ART

Granting an impedance means that an impedance presented by an input port of a device is close to a desired impedance, and simultaneously offering a transfer of power ideally without loss, or almost without loss, from the access of input to an output port of the device, in a context where the impedance seen by the output port may vary. Thus, if a signal generator having an impedance equal to the conjugate complex of the desired impedance is connected to the input port, it will provide maximum power to the input port, this maximum power being called "available power ", And the output port will deliver a power close to this maximum power.

A tunable matching circuit having a single input port and a single output port behaves, at any frequency in a given frequency band, with respect to its input port and its output port, substantially like a linear device passive with 2 accesses. Here, "passive" is used in the sense of circuit theory, so that the single input access and single output tunable tunable circuit does not provide amplification. A tunable matching circuit with single input access and single output port comprises one or more adjustable impedance devices each having an adjustable reactance. Setting tunable matching circuitry to single input access and single output port means setting the reactance of one or more of its adjustable impedance devices. A tunable matching circuit with single input access and single output port can be used to provide impedance. To provide impedance, the single-input and single-input tunable tunable matching circuit must be properly tuned.

In the following, an automatic tuning system is a device that can automatically adjust a tunable matching circuit with single input access and single output access. When it is intended to be inserted between an antenna and a radio transmitter, the automatic tuning system is sometimes referred to as "automatic antenna tuner" ("automatic antenna tuner") or "tuner module". adaptive impedance matching '(in English: "adaptive impedance matching module"). An automatic tuning system is effectively adaptive, in the sense that circuit parameters, namely the reactances of adjustable impedance devices, are changed over time, depending on circuit variables such as voltages or currents sensed.

Many automatic tuning systems have been described which use one or more actual quantities dependent on the impedance presented by the input port, these actual quantities being processed to obtain "tuning control signals", the tuning control signals being used to control the reactances of the adjustable impedance devices of a tunable matching circuit with single input access and single output access.

The block diagram of an automatic tuning system of the state of the prior art, having a user access and a target access, is shown in FIG. 1. The automatic tuning system shown in FIG. at a given frequency, a power transfer from the user access (5) to the target access (6), the automatic tuning system comprising: a detection unit (1) delivering one or more "output signals"; "detection unit", each of the detection unit output signals being mainly determined by one or more electrical variables sensed at the user access; a signal processing unit (2) estimating one or more actual quantities dependent on an impedance presented by the user access, using the detection unit output signals obtained while an excitation is applied to the access user, the signal processing unit producing an output signal; a tunable matching circuit having a single input port and a single output port (4) having one or more adjustable impedance devices, the one or more adjustable impedance devices being such that, at said given frequency, each of the one or more a plurality of adjustable impedance devices has a reactance, the reactance of any of the one or more adjustable impedance devices having an influence on the impedance presented by the user access, the reactance of any of the one or more devices with adjustable impedance being adjustable by electrical means; a tuning control unit (3), the tuning control unit receiving the output signal from the signal processing unit, the tuning control unit delivering one or more control signals d "tuning" to the tunable matching circuit having single input access and single output access, the reactance of each of the one or more adjustable impedance devices being mainly determined by at least one of the one or more tuning control signals .

In Fig. 1, the output port of the single input access and single output tunable tunable matching circuit is directly coupled to the target port (6), and the input port of the circuit tunable adaptation with single input access and single output access is indirectly coupled to the user access (5), through the detection unit (1). The detection unit is such that each of said one or more actual quantities dependent on an impedance presented by the user access is also an actual quantity dependent on the impedance presented by the input port (of the circuit). tunable adaptation to single input access and single output access). In fact, the detection unit is typically such that the impedance presented by the user access is close to the impedance presented by this input access.

For example, in an automatic tuning system disclosed in United States Patent No. 2,523,791, entitled "Automatic Tuning System", in an automatic tuning system disclosed in the United States Patent No. 2,745,067, entitled "Automatic Impedance Matching Apparatus", and in an automatic tuning system disclosed in United States Patent No. 3,443,231, entitled "Impedance Matching System", the impedance sought is resistance. We will use R0 to note this resistance. In each of these devices, a voltage v and a current i are sensed at a given point of a circuit, the impedance presented by the user access being Z-v! i. In each of these devices, the actual quantities dependent on the impedance presented by the user access are a voltage determined by the phase of v with respect to iV, this phase being equal to the argument of Z, and a voltage substantially proportional to the difference | v | - R0 j / 1. In each of these devices, the second actual quantity dependent on the impedance presented by the user access is substantially equal to zero if the impedance presented by the user access is substantially equal to the impedance sought, but the inverse is not true. In the case of said patents No. 2,745,067 and 3,443,231, the two actual quantities dependent on the impedance presented by the user access are substantially equal to zero if and only if the impedance presented by the user access is substantially equal to the impedance sought.

The automatic tuning systems disclosed in said patents 2,523,791 and 2,745,067 each correspond to the block diagram shown in FIG. 1. In the case of said patent 3,443,231, two other real quantities representative of an impedance other than the impedance presented by the user access are also used to obtain tuning control signals. Thus, the block diagram shown in FIG. 1 is not applicable to the automatic tuning system disclosed in said patent 3,443,231. However, a specialist sees that it is possible to consider that the automatic tuning system disclosed in said patent 3,443,231 actually consists of two automatic tuning systems each corresponding to the block diagram shown in Figure 1.

For example, in an automatic tuning system disclosed in U.S. Patent No. 4,356,458, entitled "Automatic Impedance Matching Apparatus" and in an automatic tuning system disclosed in the US Pat. America No. 5,225,847 entitled "Automatic Antenna Tuning System", two voltages are sensed: a voltage substantially proportional to the module of an incident voltage complex to the user access (in English "incident voltage" is said to "incident voltage" or " forward voltage "), and a voltage substantially proportional to the module of a reflected voltage complex to the user access. Using the same notations as above, vF to record the complex incident voltage at the user access, and vR to note the complex reflected voltage at the user access, the specialist understands that said modules are given by | vF | = | v + Æ0 i | / 2 and by | vR | = | v - R0 * | / 2, respectively. In each of these devices, only one actual quantity dependent on the impedance presented by the user access is used. It is a number processed in a digital circuit. In one of these devices, this number is substantially equal to the ratio between the module of the complex reflected voltage and the modulus of the complex incident voltage, that is to say vR | / 1 vF |. In the other of these devices, this number is substantially equal to the square of the inverse of this ratio, that is to say to | vF | 2/1 vR | 2.

For example, in an automatic tuning system disclosed in U.S. Patent No. 4,493,112, entitled "Antenna Tuner Discriminator", two complex voltages are sensed: a voltage substantially proportional to a voltage incident to access user, and a voltage substantially proportional to a voltage reflected at the user access. By using the incident voltage as a phase reference, a voltage proportional to the real part of the reflected voltage and a voltage proportional to the imaginary part of the reflected voltage are obtained. In this apparatus, the actual quantities dependent on the impedance presented by the user access are the voltage proportional to the real part of the reflected voltage and the voltage proportional to the imaginary part of the reflected voltage. In this apparatus, the two actual quantities dependent on the impedance presented by the user access are substantially equal to zero if and only if the impedance presented by the user access is substantially equal to the desired impedance.

In the devices disclosed in said patents Nos. 4,356,458 and 5,225,847, a digital feedback loop involving sequential logic must be used to obtain the tuning control signals and to match the impedance presented by the user access. because the unique real quantity dependent on the impedance presented by the user access does not provide complete information on the impedance presented by the user access. In the other apparatuses considered above, a faster agreement can be obtained because two real quantities dependent on the impedance presented by the user access provide complete information on the impedance presented by the user access, so that A simple negative feedback loop can be used to obtain the tuning control signals and to match the impedance presented by the user access.

The automatic tuning systems disclosed in said patents Nos. 4,356,458, 4,493,112 and 5,225,847 each correspond to the block diagram shown in FIG.

The automatic tuning system shown in Fig. 1 utilizes a closed-loop control (servo) structure, in which the actual quantities dependent on the impedance presented by the user access are used to obtain tuning control signals. , which determine the reactance of each of the adjustable impedance devices, and therefore determine the impedance presented by the user access. The specialist understands that an automatic tuning system using real quantities dependent on the impedance presented by the user access providing complete information on the impedance presented by the user access, can obtain the fastest agreement if based on this complete information obtained at a given time for known chord control signals and on a single input access and single output tunable tunable circuit model, it calculates the values of tuning control signals necessary to obtain an exact tuning and quickly delivers the corresponding tuning control signals. In this case, the calculation is very difficult, because there is no direct relationship between the actual quantities dependent on the impedance presented by the user access and the reactance value that each of the adjustable impedance devices must take. after being settled. Thus, the automatic tuning system shown in Figure 1 is slow or requires very difficult calculations. In addition, it can be shown that a tuning of a tunable matching circuit with single input access and single output access obtained using the automatic tuning system shown in FIG. 1 is not necessarily optimal. when the losses in tunable matching circuit with single input access and single output access are not very low.

The block diagram of another prior art automatic tuning system, having user access and target access, is shown in FIG. 2. The automatic tuning system shown in FIG. at a given frequency, a power transfer from the user access (5) to the target access (6), the automatic tuning system comprising: a detection unit (1) delivering one or more output signals detection unit ", each of the detection unit output signals being mainly determined by one or more electrical variables sensed at the target access; a signal processing unit (2) estimating one or more actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the access user, the signal processing unit producing an output signal; a tunable matching circuit having a single input port and a single output port (4) having one or more adjustable impedance devices, the one or more adjustable impedance devices being such that, at said given frequency, each of the one or more a plurality of adjustable impedance devices has a reactance, the reactance of any of the one or more adjustable impedance devices having an influence on the impedance presented by the user access, the reactance of any of the one or more devices with adjustable impedance being adjustable by electrical means; a tuning control unit (3), the tuning control unit receiving the output signal from the signal processing unit, the tuning control unit delivering one or more control signals d "tuning" to the tunable matching circuit having single input access and single output access, the reactance of each of the one or more adjustable impedance devices being mainly determined by at least one of the one or more tuning control signals .

In Fig. 2, the output port of the tunable matching circuit having single input access and single output port is indirectly coupled to the target port (6), through the detection unit (1), and the input port of the tunable matching circuit with single input access and single output port is directly coupled to the user access (5). The detection unit is such that each of said one or more actual quantities dependent on an impedance seen by the target access is also an actual quantity dependent on the impedance seen by the output port (of the matching circuit tunable to single input access and single output access). In fact, the detection unit is typically such that the impedance seen by the target access is close to the impedance seen by this output port.

For example, in an automatic tuning system disclosed in United States Patent No. 5,564,086, entitled "Method and apparatus for enhancing the operating characteristic of a radio transmitter" and in an automatic tuning system disclosed in US Pat. U.S. Patent No. 6,414,562 entitled "Circuit and method for impedance matching", two voltages are sensed: a voltage substantially proportional to a complex incident voltage at the target port, denoted uF, and a substantially proportional voltage at a complex reflected voltage at the target access, denoted uR. In said patent No. 5,564,086, the actual quantities dependent on an impedance seen by the target access are the modulus and the phase of the ratio between the complex reflected voltage and the complex incident voltage, that is to say the ratio uR ! uF. In said patent No. 6,414,562, the actual quantities dependent on an impedance seen by the target access are the difference between the modules of uF and uR, i.e., uF \ - \ uR |, and a function actual difference in phase between% and uR, this function being produced by a phase comparator.

The automatic tuning systems disclosed in these patents Nos. 5,564,086 and 6,414,562 each correspond to the block diagram shown in FIG.

The automatic tuning system shown in Fig. 2 uses an open loop control structure, in which the actual quantities dependent on an impedance seen by the target access are used to obtain tuning control signals, the signals tuning control having no influence on the impedance seen by the target access. The specialist understands that such an open-loop control structure automatic tuning system is explicitly or implicitly based on a tunable tunable circuit model with single input access and single output access. Using the knowledge of the operating frequency and the actual quantities dependent on an impedance seen by the target access, the automatic tuning system determines the values of the tuning control signals. This does not require difficult calculation. For example, simple interpolations are only necessary if a lookup table or look-up table is used to obtain tuning control signals, based on the operating frequency and on the actual quantities depending on the impedance seen by the target access. Unfortunately, the automatic tuning system shown in FIG. 2 frequently provides an inaccurate tuning, so that the impedance presented by the user access is not optimal.

Therefore, there is no known solution to the problem of optimally, quickly and automatically adjusting a tunable matching circuit with single input access and single output access, without very difficult calculations, or when Losses in tunable matching circuit with single input access and single output access are not very low.

DISCLOSURE OF THE INVENTION The invention relates to a method for automatically adjusting a tunable matching circuit with single input access and single output access, without the above-mentioned limitations of known techniques, and also a control system. automatic tuning using this method.

In the following, "having an influence" and "having an effect" have the same meaning.

The method according to the invention is a method for automatically adjusting a tunable matching circuit with single input access and single output access, the tunable matching circuit having single input access and single output access being a part an automatic tuning system having a "user access" and a "target access", the automatic tuning system allowing, at a given frequency, a transfer of power from the user access to the target access, the a single input access tunable tunable circuit and a single output port having one or more adjustable impedance devices, the one or more adjustable impedance devices being referred to as the "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the IEC 60050 - International Electrotechnical Vocabulary - Details for IEV number 515-04-29 Electromagnetic compatibility and electromagnetic compatibility of the tunable matching circuit having influence on an impedance presented by the user access, the reactance of any of the adjustable impedance devices of the tunable matching circuit being adjustable by electrical means, the method comprising the following steps: applying an excitation to the user access; sensing electrical variables at the target access, to obtain at least two "sensing unit output signals", each of the sensing unit output signals being primarily determined by one or more of the electrical variables sensed at the sensing unit output signal; target access; measuring, at one or more locations in the tunable matching circuit with single input access and single output access, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being mainly determined by one or more of the temperatures at said one or more locations; estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while the excitation is applied, say at least two actual quantities dependent on an impedance view by the target access being sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access; using said one or more temperature signals and say at least two actual quantities dependent on an impedance seen by the target access, to obtain one or more "tuning control signals"; applying each of the one or more tuning control signals to at least one of the adjustable impedance devices of the tunable matching circuit, the reactance of each of the adjustable impedance devices of the tunable matching circuit being primarily determined by at least one one or more tuning control signals.

According to the invention, the given frequency is for example a frequency greater than or equal to 150 kHz. We will note the impedance seen by the target access, and Ζυ the impedance presented by the user access. Z ^ and Ζυ are complex numbers dependent on frequency. Thus, the impedance seen by the target access may be called "complex impedance seen by the target access". Said power transfer from the user access to the target access may be a power transfer with low or negligible losses or zero, this characteristic being preferred.

At said one or more locations in the tunable match circuit with single input access and single output port, a temperature is measured. Thus, if said one or more locations in the tunable matching circuit having single input access and single output access comprise at least two locations, at least two temperatures are measured. Said temperature measured at each of said one or more locations in the tunable matching circuit with single input access and single output access can for example be measured repeatedly, for example once a second.

Each of said at least two actual quantities dependent on an impedance seen by the target access may for example be a real quantity representative of the impedance seen by the target access. Each of said at least two actual quantities dependent on an impedance seen by the target access may for example be substantially proportional to the module, or phase, or to the real part, or to the imaginary part of the impedance seen by the target access, or the inverse of the impedance seen by the target access (that is, the admittance seen by the target access), or a voltage reflection coefficient at the target access, defined as equal to (Zsant ~ Zo) (ZsaM + Z0) _1, where ZD is a reference impedance.

An adjustable impedance device is a component comprising two terminals which behave substantially like the terminals of a passive linear bipole, and which are therefore completely characterized by an impedance which can depend on the frequency, this impedance being adjustable. An adjustable impedance device may be mechanically adjustable, for example a variable resistor, a variable capacitor, an array having a plurality of capacitors and one or more switches or switches used to make different capacitors in the array contribute to the reactance, an inductor variable, a network comprising a plurality of inductors and one or more switches or switches used to make different network inductances contribute to the reactance, or an array comprising a plurality of open or short-circuit transmission line sections ( in English: "stubs") and one or more switches or switches used to make different sections of the transmission line of the network contribute to the reactance. We note that all the examples in this list, except the variable resistor, are intended to produce an adjustable reactance.

An adjustable impedance device having an electrically adjustable reactance may be such as to provide only, at said given frequency, a finite set of reactance values, this characteristic being for example obtained if the adjustable impedance device is: - a network comprising a plurality of capacitors or sections of transmission line in open circuit and one or more switches or switches controlled electrically, such as electromechanical relays, or microelectromechanical switches (in English: "MEMS switches"), or PIN diodes or insulated gate field effect transistors (MOSFETs), used to make different capacitors or different sections of the open circuit transmission line of the network contribute to the reactance; or a network comprising a plurality of short-circuited transmission line coils or sections and one or more electrically controlled switches or switches used to make different coils or different short-circuit transmission line sections of the network contribute to the reactance.

An adjustable impedance device having an electrically adjustable reactance may be such as to provide, at said given frequency, a continuous set of reactance values, this characteristic being for example obtained if the adjustable impedance device is based on the use of a diode with variable capacitance; or a variable capacity MOS component (in English: "MOS varactor"); or a microelectromechanical component with variable capacity (in English: "MEMS varactor"); or a ferroelectric component with variable capacity (in English: "ferroelectric varactor").

Unlike the automatic tuning system using an open loop control structure described in the prior art section above, said one or more temperature signals are used to obtain said one or more signals. Chord control. However, the skilled person understands that the invention utilizes an open loop control structure, wherein said one or more temperature signals and said at least two actual quantities dependent on an impedance seen by the target access are used to obtain tuning control signals, the tuning control signals having no influence on the impedance seen by the target access.

Let r denote the number of tuning control signals. Following an approach similar to that used in section Π of the article by F. Broydé and E. Clavelier entitled "Some Properties of Multiple-Antenna-Port and Multiple-User-Port Antenna Tuners", published in IEEE Trans. On Circuits and Systems - I: Regular Papers, Vol. 62, No. 2, pages 423-432, in February 2015, we can consider an application (in the mathematical sense) denoted g (/ and defined by

Where Z is the frequency and where the tuning control signals are numbered from 1 to r, for any integer j greater than or equal to 1 and lower or equal to r, we denote by xy the value of the chord control signal number j The specialist sees that is independent of the variables x "..., xr, while equation (1) shows that Zc / depends on the variables x "..., xr.

Experimental results have shown that temperature also often influences Z {/, and that a cause of this influence is typically the fact that the reactance and resistance of certain types of adjustable impedance devices are temperature dependent. If one or more such adjustable impedance devices are used as adjustable impedance devices of the tunable matching circuit, then the gv application applies only in a context in which a suitable set of temperatures is specified. For example, the suitable temperature set may consist of the temperature of each of the adjustable impedance devices of the tunable matching circuit, or a single temperature (e.g., if the single input tunable tunable circuit single output access is such that the adjustable impedance devices of the tunable matching circuit can be considered to be almost at the same temperature). Let q denote the number of said one or more locations in the tunable circuit with single input access and single output access, and note Tx, ..., Tq the q temperatures measured at q locations in the circuit of tunable adaptation to single input access and single output access. If the number and choice of locations is appropriate, there is an application rated gru and defined by

Smif Zsant 'xl>' -> Xr '^ l> ···> ^ q) = Zjj (2) which applies to any normal thermal environment of the tunable matching circuit with single input access and output port single, that is to say any combination of ambient temperature, temperature gradient, nearby heat sources, etc., which may occur under any condition of normal use of the single input tunable tunable circuit and single output access The gw application is a model of the tunable single input access and single output access tunable circuit, applicable to any normal thermal environment of the single input tunable tunable circuit, and This model takes into account the influences of frequency, target access impedance, tuning control signals and temperatures at said one or more locations, on the impedance presented by the user ccess.

According to the invention, said at least two actual quantities dependent on an impedance seen by the target access are sufficient to calculate. In addition, it is possible that said one or more temperature signals provide sufficiently accurate information on rl5 ..., Tg. In this case, since said one or more temperature signals and say at least two actual quantities dependent on an impedance seen by the target access are used to obtain the tuning control signals, and therefore to determine the variables x ,, ..., xr, equation (2) indicates how, according to the invention, tuning control signals can be used to automatically and accurately control Zv in any normal thermal environment of the matching circuit tunable to single input access and single output access. For example, if we want to obtain that Ζυ be close to a wanted impedance denoted Zuw at a specified frequency / ,, an equation such that

Srvi fo 'Zs <mt> xi> ··· »* / ·> T ..., Tq) - Zuw (3) can in some cases be used to implicitly define and compute appropriate values of the control signals of according to f0, Z1, ,, T ,, ..., Tq and Zuw. For example, if we want to get Ζυ to be close to Zm at the specified frequency f0, an optimization problem such that (χΐ5 ..., xr) = argmind gm (/ 0> Zsanti * 1 ··· »TX , .... Tg) ~ Zuw I) (4) can in most cases be used to compute optimal values of chord control signals, as a function of f0, Z ^, Tx, ..., Tq and ZlJW. The specialist understands how, in the automatic tuning system, tuning control signals can be obtained without complex calculation, for example using a solution-based lookup table of equation (3) or equation (4).

More generally, the automatic tuning system with open loop control structure according to the invention can take relevant temperatures into account to automatically and precisely determine, in any thermal environment, tuning control signals providing a Ζυ optimal. This can for example be obtained by using a calculation and / or data recorded in a look-up table, the calculation and / or the data recorded in the look-up table being explicitly or implicitly based on a model of the adaptation circuit tunable to single input access and single output access, this model taking into account the influences of the frequency, the at least two real quantities depending on an impedance seen by the target access, tuning control signals and temperatures to said one or more locations, on the impedance presented by the user access, or on a quantity determined by the impedance presented by the user access, such as the admittance presented by the user access or the reflection coefficient in voltage at the user access. This does not require difficult calculations. Thus, the invention overcomes the limitations of the prior art.

On the contrary, since the automatic tuning system with open loop control structure described in the section on the prior art does not take into account the relevant temperature for determining tuning control signals, it can not not provide accurate tuning if the tunable matching circuit with single input access and single output port is such that the temperature significantly influences Ζυ. Equation (4), which is only an example of a calculation technique, means that the tuning control signals are such that the impedance presented by the user access, calculated using equation (2), minimizes the absolute value of the difference between Zv and Zuw. More generally, according to the invention, it is possible for the tuning control signals to be such that the impedance presented by the user access, calculated using equation (2), reduces or minimizes the absolute value of the image of the impedance presented by the user access by a function, the function being a complex function of a complex variable. For example, said function can be defined by h {Zu) = Zv-Zm (5) the image of Zu by the function being in this case an impedance difference (i.e., a difference in complex impedances), as in equation (4), or defined by h {Zv) = Zr -'- Zlw- '(6) the image of Ζυ by the function being in this case a difference of admittances (c that is, a difference of complex admittances), or defined by h (ZL,) = (Zf / - Zuw) (Ζυ + Zw) - '(7) the image of Zu by the function being in this case a voltage reflection coefficient at the user access (that is to say, a complex voltage reflection coefficient at the user access). We note that each of these functions is such that h (Zlw) is zero.

A first apparatus implementing the method according to the invention is an automatic tuning system having a "user access" and a "target access", the automatic tuning system allowing, at a given frequency, a power transfer from the user access to the target access, the automatic tuning system comprising: a detection unit, the detection unit delivering at least two "detection unit output signals", each of the output signals of detection unit being mainly determined by one or more electrical variables sensed at the target access; a tunable matching circuit having a single input access and a single output port, the tunable matching circuit having a single input port and a single output port having one or more adjustable impedance devices, the one or more adjustable impedance being referred to as the "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of any adjustable impedance devices of the tunable matching circuit having an influence on an impedance presented by the user access, the reactance of any of the adjustable impedance devices of the tunable matching circuit being adjustable by electrical means, the circuit single input access tunable adaptation and single output access comp providing a temperature measuring device which measures, at one or more locations in the tunable matching circuit with single input access and single output port, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit, the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, said at least two actual quantities dependent on an impedance seen by the target access being sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access, the signal processing unit outputting a "tuning instruction" according to said one or more temperature signals and according to said at least two actual quantities dependent on an impedance seen by the target access; a tuning control unit, the tuning control unit receiving the tuning instruction from the signal processing unit, the tuning control unit delivering one or more tuning control signals. to the tunable matching circuit with single input access and single output access, the said one or more tuning control signals being determined according to the tuning instruction, the reactance of each of the adjustable impedance devices tunable matching circuit being mainly determined by at least one of one or more tuning control signals.

A second apparatus implementing the method according to the invention is an automatic tuning system having a "user access" and a "target access", the automatic tuning system allowing, at a given frequency, a power transfer from the user access to the target access, the automatic tuning system comprising: a detection unit, the detection unit delivering at least two "detection unit output signals", each of the output signals of detection unit being mainly determined by one or more electrical variables sensed at the target access; a tunable matching circuit having a single input access and a single output port, the tunable matching circuit having a single input port and a single output port having one or more adjustable impedance devices, the one or more adjustable impedance being referred to as the "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of any adjustable impedance devices of the tunable matching circuit having an influence on an impedance presented by the user access, the reactance of any of the adjustable impedance devices of the tunable matching circuit being adjustable by electrical means, the circuit single input access tunable adaptation and single output access comp providing a temperature measuring device which measures, at one or more locations in the tunable matching circuit with single input access and single output port, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit, the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, said at least two actual quantities dependent on an impedance seen by the target access being sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access, the signal processing unit delivering a "tuning instruction" according to said at least two actual quantities dependent on an impedance seen by the target access; a tuning control unit, the tuning control unit receiving the tuning instruction of the signal processing unit, the tuning control unit delivering one or more tuning control signals. to the tunable matching circuit with single input access and single output access, said one or more tuning control signals being determined according to said one or more temperature signals and according to the instruction of agree, the reactance of each of the adjustable impedance devices of the tunable matching circuit being mainly determined by at least one of the one or more tuning control signals.

The second apparatus embodying the method according to the invention may for example be such that the tuning instruction is also a function of said one or more temperature signals, so that in this case the instruction of agreement is issued according to said one or more temperature signals and according to said at least two actual quantities dependent on an impedance seen by the target access.

For example, each of said electrical variables may be a voltage, or an incident voltage, or a reflected voltage, or a current, or an incident current, or a reflected current.

It is assumed that said single input access and single output tunable adaptation circuit behaves at said given frequency with respect to its input port and its output port, substantially as a passive linear device. 2-port, where "passive" is used in the sense of circuit theory. As a consequence of the linearity, it is possible to define the impedance presented by the input access. As a consequence of the passivity, the tunable matching circuit with single input access and single output access does not provide amplification.

It is possible that the input access of the tunable adaptation circuit with single input access and single output access is coupled, directly or indirectly, to the user access. It is possible that the output port of the tunable adaptation circuit with single input access and single output port is coupled, indirectly through the detection unit, to the target port. Thus, said power transfer from the user access to the target access can occur through the single input access and single output access tunable adaptation circuit and through the detection unit.

The specialist understands that the automatic tuning system according to the invention is adaptive in the sense that circuit parameters, namely the reactances of the devices with adjustable impedance of the tunable matching circuit, are modified over time as a function of detection unit output signals, each of which is primarily determined by one or more electrical variables, and as a function of the temperature signals, which are each primarily determined by one or more of the temperatures at said one or more locations.

The specialist understands that the tuning instruction may for example be determined as a tuning instruction which, among a set of possible tuning instructions, produces an impedance presented by the user access, calculated with the equation (2), which reduces or minimizes the absolute value of the image of the impedance presented by the user access by a function, the function being for example one of the functions h such that A (Zf7) is given by the equation (5) or by equation (6) or by equation (7). The specialist also understands that Γ agreement instruction can for example be determined as a tuning instruction which provides an impedance presented by the user access, calculated with equation (2), which is substantially equal to the impedance search, for example a chord statement such as% u = Zuw ·

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and represented in the accompanying drawings, in which: FIG. 1 represents the block diagram of an automatic tuning system, which has already been commented in the section devoted to the presentation of the state of the art; FIG. 2 represents the block diagram of an automatic tuning system, which has already been commented on in the section devoted to the presentation of the state of the prior art; FIG. 3 represents the block diagram of an automatic tuning system according to the invention (first embodiment); FIG. 4 represents the block diagram of an automatic tuning system according to the invention (second embodiment); Fig. 5 is a schematic diagram of a tunable matching circuit having single input access and single output access, which may be used in the automatic tuning system shown in Fig. 3 (third embodiment); Fig. 6 is a schematic diagram of a tunable matching circuit having single input access and single output access, which may be used in the automatic tuning system shown in Fig. 3 (fourth embodiment); Fig. 7 is a schematic diagram of a tunable matching circuit having single input access and single output access, which may be used in the automatic tuning system shown in Fig. 4 (fifth embodiment); FIG. 8 represents the block diagram of an automatic tuning system according to the invention (sixth embodiment); Fig. 9 shows the block diagram of a radio communication transceiver having an automatic tuning system (seventh embodiment); Fig. 10 shows the block diagram of a radio communication transceiver having an automatic tuning system (eighth embodiment). DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS First embodiment.

In the context of a first embodiment of a device according to the invention, given by way of nonlimiting example, we have shown in FIG. 3 the block diagram of an automatic tuning system having a user access ( 5) and a target access (6), the automatic tuning system allowing, at a given frequency greater than or equal to 30 MHz, a transfer of power from the user access to the target access, the automatic tuning system comprising: a detection unit (1), the detection unit delivering two "detection unit output signals", each of the detection unit output signals being determined by an electrical variable sensed at the target access ; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port comprising one or more adjustable impedance devices, one or a plurality of adjustable impedance devices being referred to as "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of n any of the adjustable impedance devices of the tunable matching circuit being electrically adjustable, the tunable matching circuit having a single input access and a single output port having a temperature measuring device which measures, in one or more multiple locations in tunable matching circuit with single input access and single output access a temperature for obtaining one or more "temperature signals", each of said one or more temperature signals being determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, the signal processing unit delivering a "tuning instruction" according to said one or more temperature signals and according to said at least two actual quantities dependent on an impedance seen by the target access; a tuning control unit (3), the tuning control unit receiving the tuning instruction from the signal processing unit (2), the tuning control unit delivering one or more "Tuning control signals" to the tunable matching circuit with single input access and single output access, wherein one or more tuning control signals are determined according to the tuning instruction, the tuning reactance of each of the adjustable impedance devices of the tunable matching circuit being determined by at least one of the one or more tuning control signals.

The at least two actual quantities dependent on an impedance seen by the target access are such that they are sufficient to calculate the impedance seen by the target access. The expression "such as is sufficient to be able to calculate the impedance seen by the target access" does not imply that the impedance seen by the target access is calculated, but it is possible that the impedance seen by the target access is calculated. Since, in the two preceding sentences, "impedance" means "complex impedance", the requirement "the at least two actual quantities dependent on an impedance seen by the target access are such that they are sufficient to be able to calculate the impedance seen by the target access "is equivalent to" the at least two actual quantities dependent on an impedance seen by the target access are such that they are sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access ". The expression "as they are sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access" does not imply that the real part and the imaginary part of the impedance seen by the Target access are calculated, but it is possible that the real part and the imaginary part of the impedance seen by the target access are calculated.

The information conveyed by the detection unit output signals must be sufficient to allow the signal processing unit to estimate at least two actual quantities dependent on an impedance seen by the target access, the at least two actual quantities dependent on an impedance seen by the target access being such that they are sufficient to calculate the impedance seen by the target access. The detection unit (1) may for example be such that the two detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being a voltage at the terminals of the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a current output from the target port. Said voltage across the target access may be a complex voltage and said current exiting the target access may be a complex current. Alternatively, the detection unit (1) may for example be such that the two detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being a voltage incident on the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a reflected voltage at the target port. Said incident voltage at the target port may be a complex incident voltage and said voltage reflected at the target port may be a complex reflected voltage.

Each of the electrical variables is substantially zero if no excitation is applied to the user access and no excitation is applied to the target access.

An external device has an output port, the output port of the external device being coupled to the user port. The external device is not shown in Figure 3. The external device applies an excitation to the user access. The external device also delivers one or more "external device instructions" to the signal processing unit (2), said external device instructions informing the signal processing unit that said excitation has been applied, or is in operation. be applied, or will be applied. For example, the external device may initiate a tuning sequence when it informs the signal processing unit that it will apply the excitation to user access. For example, the signal processing unit may terminate the tuning sequence when, after the excitation has been applied, a tuning instruction has been issued. In addition, the external device provides one or more other signals to the signal processing unit and / or receives one or more other signals from the signal processing unit. The electrical connections necessary to deliver said instructions from the external device and to carry such other signals are not shown in FIG. 3. The excitation applied to the user access may for example comprise a sinusoidal signal at said given frequency. The excitation applied to the user access may for example comprise a sinusoidal signal at a frequency different from said given frequency, or a modulated sinusoidal signal. The at least two actual quantities dependent on an impedance seen by the target access may consist of a real number proportional to the real part of ZSant and a real number proportional to the imaginary part of ZSant. The specialist understands how the signal processing unit can process the detection unit output signals, to obtain a real number proportional to the real part of ZSan1 and a real number proportional to the imaginary part of ZSant. For example, assume that the sensing unit outputs: a first sensing unit output signal proportional to the voltage across the target port; and a second detection unit output signal proportional to the current output from the target access. The signal processing unit may for example perform an "in-phase / quadrature (I / Q) demodulation" (homodyne reception) of these detection unit output signals, to obtain four analog signals. These analog signals can then be converted into digital signals and then processed in the digital domain, to estimate the real part of ZSam and the imaginary part of ZSant. The signal processing unit (2) receives said one or more temperature signals provided by the tunable matching circuit with single input access and single output port, as shown in FIG. signal processing also receives the value of the frequency of the excitation applied to the user access, considered here as a specified frequency,, this value being carried by said one or more other signals. The signal processing unit has a desired impedance at the specified frequency f0, this desired impedance being denoted by Zm. The signal processing unit also knows a model of the tunable matching circuit with single input access and single output access, this model taking into account the influences of the frequency f0, the at least two real quantities depending on an impedance seen by the target access, the tuning instruction and temperatures at said one or more locations, on the impedance presented by the user access Zt /. This template is used to issue the chord statement. This model comprises: for each of the adjustable impedance devices of the tunable matching circuit, a look-up table on the characteristics of each of the adjustable impedance devices of the tunable matching circuit; and one or more formulas for calculating Zv. The chord instruction can be of any type of digital message. In this first embodiment, an adaptive process is implemented by the signal processing unit during one or more tuning sequences. The adaptive process is as follows: during each of said tuning sequences, the signal processing unit estimates the at least two actual quantities dependent on an impedance seen by the target access, and uses an algorithm to determine the statement of agreement, the tuning instruction being such that a "predicted impedance" determined using the model, the predicted impedance being expected to be ideally equal to the impedance presented by the user access (ideally means here : if the model is very precise), is as close as possible to the desired impedance. Thus, the algorithm must find a tuning instruction such that the predicted impedance, calculated using the so-called one or more formulas for calculating Ζυ, is optimized to be as close as possible to the desired impedance ZIJW. The adaptive process performed by the signal processing unit does not require difficult calculations or a lot of time, because the algorithm directly uses the frequency,, the at least two real quantities depending on an impedance seen by the target access, and temperatures at said one or more locations, to determine the tuning instruction. The tuning instruction determined as explained above is such that tuning control signals are such that the impedance presented by the user access, at a specified frequency, is close to a desired impedance (which may depend on of this specified frequency), in any normal thermal environment of the tunable matching circuit with single input access and single output access. This result is obtained because the tuning instruction is determined so that tuning control signals are such that, at said specified frequency, a predicted impedance is close to a desired impedance (which may depend on this specified frequency), the predicted impedance being determined using a single input access and single output tunable tunable circuit model, which takes into account the influences of the at least two actual quantities depending on a impedance seen by the target access, and a temperature at each of said one or more locations, on the impedance presented by the user access, or on a quantity determined by the impedance presented by the user access, such as the admittance presented by the user access or the voltage reflection coefficient to the user access.

It is important to note that in many cases, the real part and the imaginary part of the impedance of one of the adjustable impedance devices of the tunable matching circuit both depend on one or more tuning control signals. and a temperature. In fact, a typical adjustable impedance device is often optimized to provide a relatively low dependence of the reactance on temperature, so that the relative change in resistance is often greater than the relative change in reactance, for a given variation of the temperature. For example, the article by J. Nath, WM Fathelbab, PG Lam, Ghosh D., Aygün S., KG Gard, J.-P. Maria, AI Kingon and MB Steer, entitled "Discrete Barium Strontium Titanate (BST)". Thin-Film Interdigital Varactors on Alumina: Design, Fabrication, Characterization, and Applications, "published in 2006 IEEE MTT-S International Microwave Symposium Digest, pp. 552-555, in June 2006, shows that both the capacity and the loss tangent of ferroelectric ferroelectric varactor at barium and strontium titanate depend on the applied bias voltage and the temperature. In this article, over a temperature range of 0 ° C to 70 ° C, the relative variation of loss tangent was found to be much greater than the relative change in capacitance. The specialist understands that, in this context, to get Ζυ as close as possible to Z (JW, the chord instruction and chord control signals will typically be such that the reactance of any of the devices The adjustable tuning circuit of the tunable matching circuit must vary if the temperature varies, so that the automatic tuning system described in this first embodiment does not employ any form of reactance regulation, in which the instruction of and the tuning control signals would be such that the reactance of any of the adjustable impedance devices of the tunable tuning circuit should not vary if the temperature varies. estimate one or more quantities depending each on the power provided by the target access, for example, such quantities each depending on the power supplied ar target access can be used to regulate the power provided by the target access, by varying the power provided to the user access.

The reactance of any of the adjustable impedance devices of the tunable matching circuit influences an impedance presented by the user access. In addition, the tunable matching circuit with single input access and single output access has a full tuning capability, the definition of which is given in section III of said article. titled "Some Properties of Multiple-Antenna-Port and Multiple-User-Port Antenna Tuners"). Thus, the specialist understands that any small variation in the impedance seen by the target access can be fully compensated by a new automatic adjustment of the adjustable impedance devices of the tunable matching circuit. The characteristics of the tunable adaptation circuit with single input access and single output access are such that the automatic tuning system allows, at said given frequency, a low loss power transfer from the user access to the target access, and low loss power transfer from target access to user access.

If the automatic tuning system has its target access directly or indirectly coupled to an antenna, the specialist understands that Z ^ depends on the frequency and electromagnetic characteristics of the volume surrounding the antenna. In particular, if the antenna is made in a portable transceiver, for example a user equipment (in English: "user equipment" or "UE") of an LTE radio network, the body of the user has an effect on Z ^ ,, and Ζ ^ Μ depends on the position of the user's body. This is called "user interaction" ("user interaction"), or "hand effect" (in English: "hand effect") or "finger effect" (in English: "finger effect"). The specialist understands that the automatic tuning system can be used to compensate for a variation of ΖΆη1 caused by a variation in the frequency of use, and / or to compensate for user interaction.

In order to respond to variations in Z ^, and / or temperatures at said one or more locations, the chord instruction may be generated repeatedly. For example, a new chord sequence ending in the delivery of a new chord statement may begin periodically, for example every 10 milliseconds.

Second embodiment.

In the context of a second embodiment of a device according to the invention, given by way of nonlimiting example, we have shown in FIG. 4 the block diagram of an automatic tuning system having a user access ( 5) and a target access (6), the automatic tuning system allowing, at a given frequency greater than or equal to 30 MHz, a transfer of power from the user access to the target access, the automatic tuning system comprising: a detection unit (1), the detection unit delivering two "detection unit output signals", each of the detection unit output signals being determined by an electrical variable sensed at the target access ; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port comprising one or more adjustable impedance devices, one or a plurality of adjustable impedance devices being referred to as "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of n any of the adjustable impedance devices of the tunable matching circuit being electrically adjustable, the tunable matching circuit having a single input access and a single output port having a temperature measuring device which measures, in one or more multiple locations in tunable matching circuit with single input access and single output access a temperature for obtaining one or more "temperature signals", each of said one or more temperature signals being determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, the signal processing unit delivering a "tuning instruction" according to said at least two actual quantities dependent on an impedance seen by the target access; a tuning control unit (3), the tuning control unit receiving the tuning instruction from the signal processing unit (2), the tuning control unit delivering one or more "Tuning control signals" to the tunable matching circuit with single input access and single output access, said one or more tuning control signals being determined according to said one or more temperature signals and according to the tuning instruction, the reactance of each of the adjustable impedance devices of the tunable matching circuit being determined by at least one of the one or more tuning control signals.

The at least two actual quantities dependent on an impedance seen by the target access are such that they are sufficient to calculate the impedance seen by the target access.

An external device has an output port, the output port of the external device being coupled to the user port. The external device is not shown in FIG. 4. The external device applies an excitation to the user access. The external device also delivers one or more "instructions from the external device" to the signal processing unit (2). The electrical connections necessary to deliver the said instructions of the external device are not shown in FIG. 4.

In this second embodiment, the excitation is a bandpass signal (in English: "bandpass signal"). This type of signal is sometimes incorrectly called "bandwidth signal" (English "passband signal") or "narrow band signal" (in English: "narrow-band signal"). A bandpass signal is any real signal s (t), where t is the time, such that the spectrum of s (t) is included in a frequency interval \ fc - WI2, fc + W / 2] , where fc is a frequency called the "carrier frequency" and where W is a frequency called "bandwidth", which satisfies W <2 fc. Thus, the Fourier transform of s (t), denoted by 5 (/), is not negligible only within frequency intervals [- / - W / 2, -fc + W / 2] and \ fc - W / 2, fc + W / 2]. The complex envelope of the real signal s (t), called in English "complex envelope" or "complex baseband equivalent" or "baseband-equivalent signal", is a complex signal sB (t) whose Fourier transform SB (f ) is not negligible only in the frequency range [- W / 2, W / 2] and satisfies SB (f) = kS (fc + /) in this interval, where k is a real constant which is chosen equal to the root square of 2 by some authors. The real part of sB (t) is called the in-phase component, and the imaginary part of sB (t) is called the quadrature component. The specialist knows that the band-pass signal s (t) can for example be obtained: as a result of the phase and amplitude modulation of a single carrier at the frequency fc'i - as a linear combination of a first signal and a second signal, the first signal being the product of the in-phase component and a first sinusoidal carrier of frequency fc, the second signal being the product of the quadrature component and a second sinusoidal frequency carrier. The second sinusoidal carrier being 90 ° out of phase with the first sinusoidal carrier; in other ways, for example without using any carrier, for example by directly using a filtered output of a digital-to-analog converter. The frequency interval [fc - W / 2, fc + W / 2] is a passband of the bandpass signal. According to the definitions, it is clear that for a given bandpass signal, several choices of carrier frequency fc and W bandwidth are possible, so that the passband of the bandpass signal is not defined in such a way. unique. However, any passband bandwidth must contain any frequency at which the spectrum of s (t) is not negligible. The complex envelope of the real signal s (t) clearly depends on the choice of a carrier frequency. However, for a given carrier frequency, the complex envelope of the actual signal s (t) is uniquely defined for a given choice of the actual constant k. Since the excitation is a band-pass signal, it can be shown that, if the bandwidth of the excitation is sufficiently narrow, then any voltage or current measured at the target access and caused by the excitation is a bandpass signal whose complex envelope is proportional to the complex envelope of the excitation, the coefficient of proportionality being complex and independent of time. Thus we can consider that the excitation causes, at the target access: a current leaving the target access, complex envelope iTP (t); and a voltage across the target access, complex envelope vTP (t). If the bandwidth of the complex envelope of the excitation is sufficiently narrow, we have vTp (f) ~ Zsant hp (0 (8) where is the impedance seen by the target access, at the carrier frequency.

The at least two actual quantities dependent on an impedance seen by the target access may consist of a real number proportional to the modulus of the admittance seen by the target access, and a real number proportional to a phase of the admittance seen by the target access. The specialist understands how the signal processing unit can process the detection unit output signals, to obtain a real number proportional to the modulus of admittance seen by the target access, and a real number proportional to a phase the admittance seen by the target access. For example, assume that the sensing unit outputs: a first sensing unit output signal proportional to the voltage across the target port; and a second detection unit output signal proportional to the current output from the target access. The signal processing unit may, for example, perform a frequency conversion of the detection unit output signals, followed by an "in-phase / quadrature (I / Q) demodulation" (heterodyne reception), to obtain four signals. analogous, respectively proportional to the real part of v · ^ (t), to the imaginary part of vrp (t), to the real part of iTP (t), and to the imaginary part of iTP (t). These analog signals can then be converted into digital signals and then processed in the digital domain, based on equation (8), to estimate the admittance modulus seen by the target access, and the phase of the admittance seen by the target access. The tuning control unit (3) receives said one or more temperature signals provided by the tunable matching circuit with single input access and single output port, as shown in FIG. agree can be any type of digital message. In this second embodiment, an adaptive process is implemented by the signal processing unit and the tuning control unit during one or more tuning sequences. The adaptive process is as follows: during each of said tuning sequences, the signal processing unit determines the operating frequency (i.e., the carrier frequency), estimates the at least two dependent real quantities an impedance seen by the target access, and uses a look-up table to determine a tuning instruction, based on the operating frequency and on the at least two actual quantities dependent on an impedance seen by the target access. The specialist understands how to build and use such a look-up table. The tuning control unit processes the tuning instruction and said one or more temperature signals to output the tuning control signals. The tuning control signals determined as explained above are such that the admittance presented by the user access, at a specified frequency, is close to a desired admittance, in any normal thermal environment of the tunable tuning circuit. single entry access and single exit access. The adaptive process performed by the signal processing unit and the tuning control unit does not require difficult calculations or a lot of time.

Third embodiment.

The third embodiment of a device according to the invention, given by way of non-limiting example, also corresponds to the automatic tuning system shown in FIG. 3, and all the explanations provided for the first embodiment are applicable. in this third embodiment. In addition, we have shown in Figure 5 the tunable matching circuit with single input access and single output access (7) used in this third embodiment. This single input access and single output tunable tunable circuit comprises: an output port (701) having two terminals (7011) (7012), the output port being unbalanced (English: single-ended ); an input port (702) having two terminals (7021) (7022), the input port being asymmetrical; a coil (705); two adjustable impedance devices of the tunable matching circuit (703) (704), each having a negative reactance; a temperature measuring device (75) having two temperature sensors (751) (752), the temperature measuring device measuring, at the location of each of the temperature sensors, a temperature, to obtain one or more temperature, each of said one or more temperature signals being primarily determined by the temperature at the location of one of the temperature sensors; an electromagnetic screen (78), which is grounded.

All of said adjustable impedance devices of the tunable matching circuit (703) (704) are electrically adjustable, but the circuits and control links necessary to adjust the reactance of each of the adjustable impedance devices of the matching circuit The links required to power the temperature sensors (751) (752) and to convey said one or more temperature signals are not shown in FIG. 5.

As shown in FIGS. 3 and 5, the output port (701) is indirectly coupled to the target port (6) through the detection unit (1), and the port of entry (702) is directly coupled to the user access (5). Thus, at said given frequency, the impedance presented by the input port is equal to the impedance presented by the user access. The detection unit is such that, at said given frequency, the impedance seen by the output port is close to the impedance seen by the target access. It is understood by the skilled artisan that, at a rate at which the tunable matching circuit having single input access and single output port is provided to operate, the reactance of any of the adjustable impedance devices of the tunable matching circuit has an influence on the impedance presented by the user access.

Experimental results have shown that the electromagnetic characteristics of the volume surrounding the tunable matching circuit with single input access and single output access often influence Zir. The specialist understands that this phenomenon may be detrimental to the automatic tuning system according to the invention, because the invention uses an open loop control structure. Experimental results have shown that this phenomenon can be attenuated by reducing the variable electromagnetic field produced by the single input access tunable adaptation circuit and the single output access outside the tunable tunable matching circuit. single entry and single exit access. In FIG. 5, a suitable reduction of this electromagnetic field is provided by the electromagnetic screen (78), which may also be called electromagnetic shielding, and which is connected to a ground plane of the printed circuit on which the matching circuit tunable to single input access and single output access is achieved.

A first one of the temperature sensors (751) is located near a first one of the adjustable impedance devices of the tunable matching circuit (703), so that it measures a temperature which is close to the temperature of said first one of the adjustable impedance devices of the tunable matching circuit. A second one of the temperature sensors (752) is located near a second of the adjustable impedance devices of the tunable matching circuit (704), so that it measures a temperature which is close to the temperature of said second adjustable impedance devices of the tunable matching circuit. In this manner, the one or more temperature signals provide information on the temperatures of each of the adjustable impedance devices of the tunable matching circuit, which may be different from each other. The specialist understands that these temperatures may in particular be different if a significant high-frequency power is transferred from the user access to the target access, because the powers dissipated in the adjustable impedance devices of the tunable matching circuit are typically different from each other.

In this third embodiment, two adjustable impedance devices of the tunable matching circuit are used. Thus, it is possible that the number of adjustable impedance devices of the tunable matching circuit is greater than or equal to 2. As explained in said article entitled "Some Properties of Multiple-Antenna-Port and Multiple-User-Port Antenna Tuners" this is necessary to obtain a complete agreement faculty.

In this third embodiment, two temperature sensors are used, for measuring, at two locations in the tunable matching circuit with single input access and single output access, a temperature. Thus, it is possible that the number of locations in the tunable matching circuit with single input access and single output access, at which a temperature is measured, is greater than or equal to 2.

Fourth embodiment.

The fourth embodiment of a device according to the invention, given by way of non-limiting example, also corresponds to the automatic tuning system shown in FIG. 3, and all the explanations provided for the first embodiment are applicable. in this fourth embodiment. In addition, we have shown in Figure 6 the tunable matching circuit with single input access and single output access (7) used in this fourth embodiment. This single input access and single output tunable tunable circuit comprises: an output port (701) having two terminals (7011) (7012), the output port being asymmetric; an input port (702) having two terminals (7021) (7022), the input port being asymmetrical; an adjustable impedance device of the tunable matching circuit (706) having a positive reactance; two adjustable impedance devices of the tunable matching circuit (707) (708), each having a negative reactance; a temperature measuring device (75) comprising a single temperature sensor (753), the temperature measuring device measuring, to replace the temperature sensor, a temperature, to obtain one or more temperature signals, each of said one or a plurality of temperature signals being primarily determined by the temperature to be replaced by the temperature sensor; an electromagnetic screen (78), which is grounded.

All of said adjustable impedance devices of the tunable matching circuit (706) (707) (708) are electrically adjustable, but the circuits and control links necessary to adjust the reactance of each of the adjustable impedance devices of the circuit The necessary links for supplying the temperature sensor (753) and for transporting said one or more temperature signals are not shown in FIG. 6.

In this fourth embodiment, the electromagnetic screen (78) forms an enclosure containing all of said adjustable impedance devices of the tunable matching circuit (706) (707) (708), wherein the temperature is nearly uniform. That's why only one temperature sensor is used.

In this fourth embodiment, three adjustable impedance devices of the tunable matching circuit are used. Thus, it is possible for the number of adjustable impedance devices of the tunable matching circuit to be greater than or equal to 3.

Fifth embodiment.

The fifth embodiment of a device according to the invention, given by way of non-limiting example, also corresponds to the automatic tuning system shown in FIG. 4, and all the explanations provided for the second embodiment are applicable. in this fifth embodiment. In addition, we have shown in Fig. 7 the tunable matching circuit with single input access and single output access (7) used in this fifth embodiment. This single input access and single output tunable tunable circuit comprises: an output port (701) having two terminals (7011) (7012), the output port being symmetrical; an input port (702) having two terminals (7021) (7022), the input port being asymmetrical; a coil (705); a transformer (709); two adjustable impedance devices of the tunable matching circuit (703) (704), each having a negative reactance; a temperature measuring device comprising three temperature sensors (751) (752) (754), the temperature measuring device measuring, at the location of each of the temperature sensors, a temperature, to obtain one or more signals of temperature, each of said one or more temperature signals being primarily determined by the temperature at the location of one of the temperature sensors.

All of said adjustable impedance devices of the tunable matching circuit (703) (704) are electrically adjustable, but the circuits and control links necessary to adjust the reactance of each of the adjustable impedance devices of the matching circuit The links required to transport said one or more temperature signals are not shown in FIG. 7.

A first one of the temperature sensors (751) is located near a first one of the adjustable impedance devices of the tunable matching circuit (703), so that it measures a temperature which is close to the temperature of said first one of the adjustable impedance devices of the tunable matching circuit. A second one of the temperature sensors (752) is located near a second of the adjustable impedance devices of the tunable matching circuit (704), so that it measures a temperature which is close to the temperature of said second adjustable impedance devices of the tunable matching circuit. A third of the temperature sensors (754) is near the coil (705), so that it measures a temperature that is close to the temperature of the coil. In this manner, the one or more temperature signals provide information on the temperatures of the coil and each of the adjustable impedance devices of the tunable matching circuit, which may be different from each other. The specialist understands that these temperatures can in particular be different if a significant high-frequency power is transferred from the user access to the target access. The coil used in this fifth embodiment has a ferrite core, so that its inductance and losses depend on the temperature of the coil. This is why the third of the temperature sensors (754) is present.

In this fifth embodiment, the transformer (709) is used to obtain a symmetrical output port. Such a transformer is often called a balun. Since the output port is symmetrical, the target access is symmetrical.

More generally, according to the invention, it is possible for the input access and / or the output access of the tunable adaptation circuit with single input access and single output access to be asymmetrical, and it is possible that that the input port and / or the output port of the tunable matching circuit with single input access and single output port are symmetrical. Thus, according to the invention, it is possible that the target access and / or the user access are asymmetrical, and it is possible that the target access and / or the user access are symmetrical.

In this fifth embodiment, three temperature sensors are used to measure, at three locations in the tunable matching circuit with single input access and single output access, a temperature. Thus, it is possible that the number of locations in the tunable matching circuit with single input access and single output access, at which a temperature is measured, is greater than or equal to 3.

Sixth embodiment.

According to a sixth embodiment of a device according to the invention, given by way of non-limiting example, we have shown in FIG. 8 the block diagram of an automatic tuning system having user access ( 5) and a target access (6), the automatic tuning system allowing, at a given frequency greater than or equal to 300 MHz, a transfer of power from the user access to the target access, the automatic tuning system comprising: a detection unit (1), the detection unit delivering two "detection unit output signals", each of the detection unit output signals being mainly determined by an electrical variable sensed at the access target; an additional detection unit (8), the additional detection unit delivering one or more "additional detection unit output signals", each of the additional detection unit output signals being mainly determined by one or more variables electrically sensed at user access; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port comprising one or more adjustable impedance devices, one or a plurality of adjustable impedance devices being referred to as "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of n any of the adjustable impedance devices of the tunable matching circuit being electrically adjustable, the tunable matching circuit having a single input access and a single output port having a temperature measuring device which measures, in one or more multiple locations in tunable matching circuit with single input access and single output access a temperature for obtaining one or more "temperature signals", each of said one or more temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, the signal processing unit delivering a "tuning instruction" according to said one or more temperature signals and according to said at least two actual quantities dependent on an impedance seen by the target access, using the additional detection unit output signals; a tuning control unit (3), the tuning control unit receiving the tuning instruction from the signal processing unit (2), the tuning control unit delivering one or more "Tuning control signals" to the tunable matching circuit with single input access and single output access, wherein one or more tuning control signals are determined according to the tuning instruction, the the reactance of each of the adjustable impedance devices of the tunable matching circuit being mainly determined by at least one of the one or more tuning control signals.

As in the first embodiment, the detection unit (1) may for example be such that the two detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable the first electrical variable being a voltage across the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a current output from the target port. Said voltage across the target access may be a complex voltage and said current exiting the target access may be a complex current. Alternatively, the detection unit (1) may for example be such that the two detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being a voltage incident on the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a reflected voltage at the target port. Said incident voltage at the target port may be a complex incident voltage and said voltage reflected at the target port may be a complex reflected voltage. The additional detection unit (8) may for example be such that the additional detection unit output signals comprise: a first additional detection unit output signal proportional to a first electrical variable, the first electrical variable being a voltage across the user access; and a second additional detection unit output signal proportional to a second electrical variable, the second electrical variable being a current entering the user access. Said voltage across the user access may be a complex voltage and said current entering the user access may be a complex current. Alternatively, the additional detection unit (8) may for example be such that the additional detection unit output signals comprise: a first additional detection unit output signal proportional to a first electrical variable, the first variable electrical being an incident voltage to the user access; and a second additional detection unit output signal proportional to a second electrical variable, the second electrical variable being a voltage reflected at the user access. Said incident voltage to the user access may be a complex incident voltage and said voltage reflected at the user access may be a complex reflected voltage.

Seventh embodiment.

According to a seventh embodiment of the invention, given by way of non-limiting example, we have shown in FIG. 9 the block diagram of a transceiver for radio communication using an automatic tuning system according to the invention. The transceiver shown in Fig. 9 is a transceiver for radio communication in a given frequency band, comprising: an antenna (11), an antenna operating in the given frequency band; an antenna link (10), the antenna link having a far end and a near end, the antenna being coupled to the far end of the antenna link, the near end of the antenna link presenting, at a frequency in the given frequency band, an impedance called "the impedance presented by the near end of the antenna link"; a radio device (9) which consists of all parts of the transceiver not shown elsewhere in Figure 9, the radio device having radio access, the radio device providing "chord sequence instructions" which indicate when a tuning sequence is being performed, an excitation being delivered by the radio access during said tuning sequence; a detection unit (1), the detection unit delivering two "detection unit output signals", each of the detection unit output signals being mainly determined by an electrical variable sensed at the near end of the detection unit; the antenna link; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port having an output port that is indirectly coupled to the near end of the antenna link (10) through the detection unit (1), the tunable matching circuit having single input access and single output access having an input port which is directly coupled to the radio access of the radio device (9), the single input access tunable matching circuit and the single output access having one or more adjustable impedance devices, the one or more adjustable impedance devices being referred to as the "devices with adjustable impedance of the tunable matching circuit "and being such that, at said frequency in the given frequency band, each of the adjustable impedance devices of the circuit tunable adaptation to a reactance, the reactance of any of the adjustable impedance devices of the tunable matching circuit being electrically adjustable, the tunable matching circuit having a single input access and a single output port having a device temperature measuring device which measures, at one or more locations in the tunable matching circuit with single input access and single output access, a temperature, to obtain one or more "temperature signals", each of said one or more a plurality of temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on the impedance presented by the near end of the antenna link, using the chord sequence instructions and using the detection unit output signals obtained while the excitation was being delivered by the radio access during a tuning sequence, the signal processing unit delivering a "tuning instruction" as a function of said one or more temperature signals and according to said at least two actual quantities dependent on the impedance presented by the near end of the antenna link; a tuning control unit (3), the tuning control unit receiving the tuning instruction from the signal processing unit (2), the tuning control unit delivering one or more "Tuning control signals" to the tunable matching circuit with single input access and single output access, wherein one or more tuning control signals are determined according to the tuning instruction, the the reactance of each of the adjustable impedance devices of the tunable matching circuit being mainly determined by at least one of the one or more tuning control signals.

The specialist understands that said "impedance presented by the near end of the antenna link" of this seventh embodiment corresponds to said "impedance seen by the target access" of the first embodiment and the second embodiment, evaluated at said frequency in the given frequency band.

The specialist understands that any small variation in the antenna impedance produced by a change in frequency of use or a change in the medium surrounding the antenna, for example caused by the user interaction, can be compensated for by an adjustment automatic adjustable impedance devices of the antenna tuner. Thus, it is always possible to obtain the best performance using the transceiver.

In order to respond to changes in antenna impedance and / or temperatures at said one or more locations, the tuning instruction may be generated repeatedly. For example, a new chord sequence ending in the delivery of a new chord statement may begin periodically, for example every 10 milliseconds. The transceiver is used for radio transmissions in a cellular network. The excitation is a bandpass signal, as in the second embodiment. The excitation is compatible with the requirements of standards typically applicable to cellular networks.

Eighth embodiment.

According to an eighth embodiment of the invention, given by way of non-limiting example, we have shown in FIG. 10 the block diagram of a transceiver for radio communication using an automatic tuning system according to the invention. The transceiver shown in FIG. 10 is a transceiver for radio communication in a given frequency band, comprising: N = 3 antennas (11), each of the N antennas being such that it can operate at any frequency in the given frequency band; a radio device (9) which consists of all parts of the transceiver not shown elsewhere in Figure 10, the radio device having radio access, the radio device providing "chord sequence instructions" which indicate when a tuning sequence is being performed, an excitation being delivered by the radio access during said tuning sequence; a switching unit (12), the switching unit receiving a "configuration instruction" generated automatically by the radio device, the switching unit having N "antenna access" each coupled to one and only one of the antennas through a antenna link (10), the switching unit having a "network access", the switching unit operating in an active configuration determined by the configuration instruction, the active configuration being one of a plurality of permissible configurations, the switching unit providing, in any of the permitted configurations, for signals in the given frequency band, a bidirectional path between the network access and one and only one of the antenna accesses, the network access presenting, at a frequency in the given frequency band, an impedance called "the impedance presented by the network access"; a detection unit (1), the detection unit delivering two "detection unit output signals", each of the detection unit output signals being mainly determined by an electrical variable sensed at the network access; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port having an output port that is indirectly coupled to the network access through the detection unit (1), the single input access tunable adaptation circuit and the single output access having an input port which is directly coupled to the radio access of the radio device (9). ), the single input access and tunable single input access tunable circuit having one or more adjustable impedance devices, the one or more adjustable impedance devices being referred to as the tunable matching circuit adjustable impedance devices. And such that, at said frequency in the given frequency band, each of the adjustable impedance devices of the tunable matching circuit has a reactive wherein the reactance of any of the adjustable impedance devices of the tunable tuning circuit is electrically adjustable, the tunable matching circuit having a single input port and a single output port having a temperature measuring device which measures, at one or more locations in the single input access tunable matching circuit and the single output access, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on the impedance presented by the network access, using the tuning sequence instructions and using the signaling signals; detection unit output obtained while the excitation was being delivered by the radio access during a tuning sequence, the signal processing unit delivering a "tuning instruction" according to said one or more signals of temperature and according to said at least two real quantities dependent on the impedance presented by the network access; a tuning control unit (3), the tuning control unit receiving the tuning instruction from the signal processing unit (2), the tuning control unit delivering one or more "Tuning control signals" to the tunable matching circuit with single input access and single output access, wherein one or more tuning control signals are determined according to the tuning instruction, the the reactance of each of the adjustable impedance devices of the tunable matching circuit being mainly determined by at least one of the one or more tuning control signals.

The specialist understands that said "network access impedance" of this eighth embodiment corresponds to said "target access impedance" of the first embodiment and the second embodiment, evaluated at said frequency in the first embodiment. given frequency band. The switching unit operates (or is used) in an active configuration determined by the configuration instruction, the active configuration being an authorized configuration among a plurality of authorized configurations, the switching unit providing, in any of the permissible configurations, for signals in the given frequency band, a path between the network access and one of the antenna ports. Thus, the switching unit operates in an active configuration which is one of the authorized configurations, and each authorized configuration corresponds to a selection of an antenna access among the N antenna accesses. The switching unit provides, for signals in the given frequency band, a path between the network access and the selected antenna access. This path may preferentially be a low-loss path for signals in the given frequency band. The specialist understands that a suitable switching unit may comprise one or more electrically controlled switches and / or switches (here, "electrically controlled" means "controlled by electrical means"). In this case, one or more of said electrically controlled switches and / or switches may for example be an electromechanical relay, or a micro-electromechanical switch (in English: "MEMS switch"), or a circuit using one or more PIN diodes and / or one or more insulated gate field effect transistors (MOSFETs) as switching devices.

For example, the configuration instruction may be determined based on one or more of the following variables: say at least two actual quantities dependent on the impedance presented by the network access; one or more location variables, each of the location variables depending, in a given usage pattern, on the distance between a portion of a human body and an area of the transceiver; the frequencies used for radio communication with the selected antenna; one or more additional variables, each of the additional variables being an element of a set of additional variables, the elements of the set of additional variables including: communication type variables which indicate whether a radio communication session is a session of voice communication, a data communication session or other type of communication session; a hands-free activation indicator; a loudspeaker activation indicator; variables obtained using one or more accelerometers; user identity variables that depend on the identity of the current user; reception quality variables; and emission quality variables.

For example, at least one of the location variables may be an output of a pressure sensitive sensor exerted by a portion of a human body. For example, at least one of the location variables may be an output of a proximity sensor. For example, at least one of the location variables can be determined by a change of state of an output of a touch screen.

The elements of said set of additional variables may further include one or more variables that are different from the location variables and that characterize the manner in which a user holds the transceiver. The configuration instruction can for example be determined using a look-up table.

INDICATIONS ON INDUSTRIAL APPLICATIONS

The method according to the invention is adapted to automatically and optimally adjust a tunable matching circuit with single input access and single output access, and the automatic tuning system according to the invention can automatically and automatically adjust optimal tunable tuning circuit with single input access and single output access. The automatic tuning system according to the invention can be a part of a radio receiver, or a radio transmitter. In such applications, the target access of the automatic tuning system according to the invention can be directly or indirectly coupled to an antenna, and the user access of the automatic tuning system according to the invention can be coupled to a remote access. radio frequency signal input of the radio receiver, or to a radiofrequency signal output port of the radio transmitter.

The method and the automatic tuning system according to the invention can optimally, quickly and automatically adjust the tunable matching circuit with single input access and single output access, without very difficult calculations. The invention is therefore particularly suitable for mobile radio transmitters, for example those used in portable radiotelephones or laptops, which can be subject to rapid variations in the electromagnetic characteristics of the medium surrounding the one or more antennas used for radio communications.

Claims (10)

A method for automatically adjusting a tunable matching circuit with single input access and single output access (7), the single input access tunable matching circuit and the single output access being a part of a automatic tuning system having a "user access" (5) and a "target access" (6), the automatic tuning system allowing, at a given frequency, a transfer of power from the user access to the access target, the single input access tunable adaptation circuit and single output access having one or more adjustable impedance devices, the one or more adjustable impedance devices being referred to as the adjustable impedance devices of the tunable matching circuit And being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of any which adjustable impedance devices of the tunable matching circuit have an influence on an impedance presented by the user access, the reactance of any of the adjustable impedance devices of the tunable matching circuit being electrically adjustable, the method comprising the steps of: applying an excitation to the user access; sensing electrical variables at the target access, to obtain at least two "sensing unit output signals", each of the sensing unit output signals being primarily determined by one or more of the electrical variables sensed at the sensing unit output signal; target access; measuring, at one or more locations in the tunable matching circuit with single input access and single output access, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being mainly determined by one or more of the temperatures at said one or more locations; estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while the excitation is applied, say at least two actual quantities dependent on an impedance view by the target access being sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access; using said one or more temperature signals and say at least two actual quantities dependent on an impedance seen by the target access, to obtain one or more "tuning control signals"; applying each of the one or more tuning control signals to at least one of the adjustable impedance devices of the tunable matching circuit, the reactance of each of the adjustable impedance devices of the tunable matching circuit being primarily determined by at least one one or more tuning control signals. 2. Method according to claim 1, wherein the tuning control signals are such that the impedance presented by the user access, at a specified frequency, is close to a desired impedance, in any normal thermal environment of the circuit. tunable adaptation with single input access and single output access. The method according to claim 2, wherein the tuning control signals are such that, at said specified frequency, a predicted impedance is close to the desired impedance, the predicted impedance being determined using a circuit model of tunable adaptation to single input access and single output access, this model taking into account the influences of the at least two actual quantities depending on an impedance seen by the target access, and a temperature at each of said one or multiple locations, on the impedance presented by the user access, or on a quantity determined by the impedance presented by the user access. 4. Automatic tuning system having a "user access" (5) and a "target access" (6), the automatic tuning system allowing, at a given frequency, a transfer of power from the user access to the target access, the automatic tuning system comprising: a detection unit (1), the detection unit delivering at least two "detection unit output signals", each of the detection unit output signals mainly determined by one or more electrical variables sensed at the target access; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port comprising one or more adjustable impedance devices, one or a plurality of adjustable impedance devices being referred to as "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of n any of the adjustable impedance devices of the tunable matching circuit having an influence on an impedance presented by the user access, the reactance of any of the adjustable impedance devices of the tunable matching circuit being adjustable by electrical means , tunable matching circuit with single input access and single output access having a temperature measuring device which measures, at one or more locations in the tunable matching circuit with single input access and single output port, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, said at least two actual quantities dependent on an impedance seen by the target access being sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access the signal processing unit outputting a "tuning instruction" as a function of said one or more temperature signals and as a function of said at least two actual quantities dependent on an impedance seen by the target access; a tuning control unit (3), the tuning control unit receiving the tuning instruction from the signal processing unit, the tuning control unit delivering one or more tuning signals; tuning circuitry to the single input access tunable matching circuit and the single output port, wherein said one or more tuning control signals are determined according to the tuning instruction, the reactance of each adjustable impedance devices of the tunable matching circuit being mainly determined by at least one of the one or more tuning control signals. An automatic tuning system according to claim 4, wherein the detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being a voltage at terminals of the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a current output from the target port. An automatic tuning system according to claim 4, wherein the detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being an incident voltage at the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a reflected voltage at the target port. 7. Automatic tuning system having a "user access" (5) and a "target access" (6), the automatic tuning system allowing, at a given frequency, a transfer of power from the user access to the target access, the automatic tuning system comprising: a detection unit (1), the detection unit delivering at least two "detection unit output signals", each of the detection unit output signals mainly determined by one or more electrical variables sensed at the target access; a tunable matching circuit having a single input access and a single output port (7), the tunable matching circuit having a single input access and a single output port comprising one or more adjustable impedance devices, one or a plurality of adjustable impedance devices being referred to as "adjustable impedance devices of the tunable matching circuit" and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of n any of the adjustable impedance devices of the tunable matching circuit having an influence on an impedance presented by the user access, the reactance of any of the adjustable impedance devices of the tunable matching circuit being adjustable by electrical means , tunable matching circuit with single input access and single output access having a temperature measuring device which measures, at one or more locations in the tunable matching circuit with single input access and single output port, a temperature, to obtain one or more "temperature signals", each of said one or more temperature signals being primarily determined by one or more of the temperatures at said one or more locations; a signal processing unit (2), the signal processing unit estimating at least two actual quantities dependent on an impedance seen by the target access, using the detection unit output signals obtained while an excitation is applied to the user access, said at least two actual quantities dependent on an impedance seen by the target access being sufficient to be able to calculate a real part and an imaginary part of the impedance seen by the target access the signal processing unit outputting a "tuning instruction" as a function of said at least two actual quantities dependent on an impedance seen by the target access; a tuning control unit (3), the tuning control imitating receiving the tuning instruction from the signal processing unit, the tuning control unit delivering one or more tuning signals; tuning circuitry to the single input access tunable circuit and the single output port, wherein said one or more tuning control signals are determined according to said one or more temperature signals and as a function of the tuning instruction, the reactance of each of the adjustable impedance devices of the tunable tuning circuit being mainly determined by at least one of the one or more tuning control signals. An automatic tuning system according to claim 7, wherein the detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being a voltage at terminals of the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a current output from the target port. An automatic tuning system according to claim 7, wherein the detection unit output signals comprise: a first detection unit output signal proportional to a first electrical variable, the first electrical variable being an incident voltage at the target access; and a second detection unit output signal proportional to a second electrical variable, the second electrical variable being a reflected voltage at the target port. 10. Automatic tuning system according to any one of claims 7 to 9, wherein the tuning instruction is issued according to said one or more temperature signals and according to said at least two actual quantities dependent on an impedance seen by the target access.