JP6128653B2 - High frequency rectifier circuit - Google Patents

Description

  The present invention relates to a high frequency rectifier circuit.

Conventionally, a single shunt type rectifier circuit is known as an example of a high-frequency rectifier circuit that converts a high-frequency signal into a DC signal in a rectenna device (Patent Documents 1-3).
FIG. 12 is a basic circuit diagram of a conventional single shunt rectifier circuit. The rectifier circuit shown in FIG. 12 includes an input terminal 91, an output terminal 92, a diode element 93, a capacitor element 95, an input matching circuit 96, and a filter circuit 97 that removes high frequency components and outputs only a DC component. Here, the operation of the rectifier circuit will be described with reference to FIGS. FIG. 13 is an image diagram showing the operating principle of a conventional high-frequency rectifier circuit. FIG. 13A illustrates an image diagram illustrating the operating principle of the rectifier circuit illustrated in FIG. 12 in an ideal state without a voltage drop. FIG. 13B shows an image diagram showing the voltage change immediately after the high-frequency signal input at the point A shown in FIG. FIG. 13C illustrates an image diagram illustrating a voltage change in a steady state at the output terminal 92 illustrated in FIG. 12.

In FIG. 12, the high frequency signal input from the input terminal 91 is input to the diode element 93 via the capacitor element 95 having the capacitor C and the input matching circuit 96. In the input signal, since the diode element 93 is connected in the reverse direction, a current flows through the diode element 93 at a negative forward drop voltage V ₀ or less, and electric charge is supplied to the capacitor element 95 to be stored (FIG. 13). (A)). As the charge is stored in the capacitive element 95, the DC voltage at point A in FIG. At point A in FIG. 12, when the negative peak value of the boosted high-frequency signal becomes equal to or higher than V _0, no current flows through the diode element 93 (FIG. 13B). From the boosted high frequency signal, the high frequency component is removed by the filter circuit 97, and only the direct current component is output from the output terminal 92 (FIG. 13C). At this time, the output voltage Vout can be expressed by Expression (1).

In addition, the 1st term of Formula (1) represents the electrical storage to a capacitive element, and the 2nd term is a term showing the discharge from a capacitive element. The parameter A ₁ represents a loss in the rectifier circuit, the parameter A ₃ shows the discharge rate from the stored electric capacitance element. Parameters A ₂ and A ₄ indicate parameters related to power storage and discharge time. Here, when the first term is larger than the second term, the high frequency signal is boosted and then output as a DC signal.

JP 2012-75227 A JP 2007-116515 A JP-A-5-335811

By the way, in the conventional single-shunt type high-frequency rectifier circuit, when the frequency of the high-frequency signal increases, signal leakage due to parasitic capacitance such as a diode element cannot be ignored, the amount of stored electricity decreases, and a voltage drop as shown in FIG. Occurs. FIG. 14 is an image diagram showing that a voltage drop has occurred in the high frequency band of the conventional rectifier circuit at point A in FIG. Due to this voltage drop, the negative peak value of the high-frequency signal becomes Vmin equal to or lower than V ₀ , and a phenomenon has occurred in which the boosted voltage is lowered from the ideal operation. As a result, there is a problem that the output power output from the output terminal 92 is reduced and the conversion efficiency is lowered.

Here, the operation of the conventional single shunt rectifier circuit will be described with reference to FIGS. 15, 16, and 17. FIG. FIG. 15 is an equivalent circuit of a diode element simplified for explaining the operating principle of a conventional single-shunt rectifier circuit. The equivalent circuit of the diode element shown in FIG. 15 has a resistance element 13 (resistance value R _d ) and a capacitance element 14 (capacitance value C _d ) connected in parallel.

FIG. 16 is a diagram showing an equivalent circuit of a general diode element. The equivalent circuit of the diode element shown in FIG. 16 includes an input terminal 101, an output terminal 102, a junction resistance (resistance value R _v ) 103, a junction capacitance (capacitance value C _j ) 104, a contact resistance (resistance value R _S ) 105, a parasitic element. It has a capacity (capacitance value C _p ) 106. When the equivalent circuit of the diode element shown in FIG. 16 is converted into the equivalent circuit of the diode element shown in FIG. 15, the equivalent circuit composed of the resistor element and the capacitor element shown in FIG. 17 can be obtained. 17 is an equivalent circuit diagram in which the diode element shown in FIG. 16 is converted to the diode element shown in FIG. Here, the resistance value R _d of the resistance element 113 and the capacitance value C _d of the capacitance element 114 can be calculated from the following equations (2) and (3).

Each of the resistance element R _d and the capacitance element C _d has frequency dependence, but here it is assumed that there is no frequency dependence. From this assumption, the equivalent circuit of the general diode element shown in FIG. 16 can be replaced with the simplified equivalent circuit of the diode element shown in FIG.
Here, the capacitance value C _d of the capacitance of the diode element element 14 is constant, the voltage applied to the diode element below the forward drop voltage (-V _0), the resistance value R _d of the resistance element 13 the resistance value R _{Let doff} . When the voltage applied to the diode element is equal to or higher than the forward voltage drop (−V ₀ ), the resistance value R _d of the resistance element 13 is set to the resistance value R _don . Admittance Y _d at this time diode element is given by Equation (4).

The impedance _{Z d} of the diode element is given by Equation (5).

Here, the real component R _e (Z _d ) and the imaginary component Im (Z _d ) of the impedance Z _d are given by the equations (6) and (7), respectively.

Here, assuming that the numerator and denominator of the imaginary component Im (Z _d ) are f (x) and g (x), respectively, f (x) and g (x) are the expressions (8) and (9), respectively. Given in.

Differentiating the imaginary component Im (Z _d ) of Expression (7) can be expressed by Expression (10).

Since the denominator of the equation (10) is always a positive value, the frequency change of the imaginary component Im (Z _d ) only needs to be calculated for the numerator of the equation (10). The numerator of formula (10) can be determined by formula (11).

  When the equation shown in Equation (12) is solved for ω, Equation (13) is obtained.

  However, since ω> 0, the solution of equation (13) is the equation shown in equation (14).

From equation (6), the real component R _e (Z _d ) of the impedance Z _d of the diode element monotonously decreases as the frequency increases. On the other hand, the imaginary component Im (Z _d ) has a frequency characteristic in which ω is a value shown in the equation (14) and has a minimum value. Above the forward voltage drop (−V ₀ ) where the value of R _d is small, the imaginary component Im (Z _d ) decreases monotonously as the frequency increases. Below the forward voltage drop (−V ₀ ) where the value of R _d is large, ω is equal to or greater than the value shown in Equation (14), and the absolute value of the imaginary component Im (Z _d ) decreases monotonously as the frequency increases. To do. In other words, below the forward voltage drop (−V ₀ ), it can be seen that the impedance Z _d of the diode element decreases as the frequency increases above the minimum value. As a result, the on / off ratio of the diode element in the high frequency band is lowered, and the conversion efficiency of the rectifier is lowered. FIG. 4 shows the calculation result of the imaginary component Im (Z _d ) of the impedance Z _d when Cd = 0.3 pF, R _doff = 1000 ohm, and R _don = 10 ohm. The triangle shown in FIG. 4 is the calculation result of R _doff = 1000 ohm, and the triangle painted black is the calculation result of R _don = 10 ohm. As shown in FIG. 4, it can be seen that the difference between R _don and R _doff decreases as the frequency increases.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high-frequency rectifier circuit that can suppress a drop in boosted voltage due to signal leakage of a diode element or the like even in a high-frequency band. .

  One embodiment of the present invention includes an input terminal for inputting a high-frequency signal; a capacitor element having one end connected to the input terminal; a matching circuit having one end connected to the other end of the capacitor element; A diode element having a cathode connected to the end; a filter circuit connected to the other end of the matching circuit; a transmission line having one end connected to the anode of the diode element and the other end grounded; An output terminal for outputting a DC signal at the end, and a reactance component of a series body having the diode element and the transmission line at a use frequency when a predetermined voltage is applied to the diode element in a reverse direction. Is a high-frequency rectifier circuit characterized by series resonance.

  One embodiment of the present invention is the above-described high-frequency rectifier circuit, wherein the electrical length of the transmission line is represented by the following formula (formula (19) in the embodiment) of the electrical length at the use frequency. The

  Another embodiment of the present invention is the above-described high-frequency rectifier circuit, in which the diode element is a junction capacitor having an electric length of the transmission line approaching 90 degrees when a forward voltage is applied. .

  As described above, according to the present invention, the parameters of the transmission line are set so that the reactance component of the series body having the diode element and the transmission line when a reverse voltage is applied resonates in series at the operating frequency. Is set. Thereby, it is possible to provide a high-frequency rectifier circuit that can suppress a drop in the boosted voltage due to signal leakage of a diode element or the like even in a high-frequency band.

It is a block diagram which shows the structure of the high frequency rectifier circuit in embodiment of this invention. It is an equivalent circuit diagram of the high frequency rectifier circuit using the simplified diode element in embodiment of this invention. It is a diagram showing the frequency dependence of the electrical length E of the transmission line to the imaginary component of the impedance Z _d zero in the embodiment of the present invention. It is a figure which shows the frequency dependence of the imaginary component of the impedance of the diode element (structure of this embodiment) of this embodiment, and the simplified diode element (conventional structure) shown in FIG. It is a circuit diagram for showing the effect of the high frequency rectifier circuit in the embodiment of the present invention. It is a circuit diagram for showing the effect of the conventional high frequency rectifier circuit. It is a figure which shows the frequency dependence of the S parameter of the diode element shunt-connected in embodiment of this invention, a transmission line, and the shunt-connected diode element of the conventional structure. It is an image figure which shows the operating principle of the high frequency rectifier circuit in embodiment of this invention. It is a figure explaining the comparison of the calculation example of the conversion efficiency of the concrete circuit (FIG. 10) of the high frequency rectifier circuit in embodiment of this invention, and the concrete circuit (FIG. 11) of the conventional high frequency rectifier circuit. It is a figure which shows the example of the concrete circuit diagram of the high frequency rectifier circuit in embodiment of this invention. It is a figure which shows the example of the concrete circuit diagram of the conventional high frequency rectifier circuit. It is a block diagram which shows the structure of the conventional high frequency rectifier circuit. It is an image figure which shows the operation principle in the ideal state without the voltage drop of the conventional high frequency rectifier circuit. It is an image figure which shows the subject in the high frequency band of the conventional high frequency rectifier circuit. It is the equivalent circuit schematic of the simplified diode element. It is an equivalent circuit diagram of a general diode element. FIG. 17 is an equivalent circuit diagram in which the diode element of FIG. 16 is converted to the diode element of FIG. 15.

FIG. 1 is a circuit diagram of a single-shunt type high-frequency rectifier circuit (hereinafter referred to as “rectifier circuit”) 10. The rectifier circuit 10 includes an input terminal 1 for inputting a high frequency signal, an output terminal 2 for outputting a DC signal, a diode element 3, a transmission line 4, a capacitive element 5, an input matching circuit 6, and a filter circuit 7.
Hereinafter, the single shunt rectifier circuit 10 according to the present embodiment will be described with reference to the drawings.
FIG. 2 is a circuit diagram in which the transmission line 25 is connected to a simplified equivalent circuit of the diode element 3 in order to explain the operation principle of the rectifier circuit 10. A resistance element 23 (resistance value R _d ), a capacitance element 24 (capacitance value C _d ), and a transmission line 25 are connected in parallel. Here, the resistive element 23 is the resistance _{R d,} the capacitance of the capacitor 24 is _{C d.}
Resistance _{R d} of the resistance element 23 shown in FIG. 2, as in the case of the conventional circuit of FIG. 15, in the following forward voltage drop _{V 0 R doff,} and _{R don} the forward voltage drop greater than or equal _{to V 0.} At this time, the impedance Z _dnew of the circuit shown in FIG. 2 is expressed by Expression (15).

Z _d represents the impedance of the diode element 3, and Z _TL represents the impedance of the transmission line 25. Impedance _{Z TL} of the transmission line 25, with characteristic impedance _{Z c,} the formula (16).

E is the electrical length of the transmission line. Here, the case of applying a predetermined reverse voltage to the diode element 3, _{R d} is the impedance _{Z Dnewoff} impedance _{Z Dnew} as the _{R doff.} Further, when the forward voltage V ₀ is applied to the diode element 3, the impedance Z _{dnew at} which R _d becomes R _don is _defined as the impedance Z _dnewon .
In order for the impedance Z _{dnewoff to} be short-circuited, the imaginary component of equation (15), that is, the reactance component of the series body having the diode element 3 and the transmission line 25, should be zero as shown in equation (17). .

  When formula (17) is arranged by tanE, it is represented by formula (18).

  Therefore, the electrical length E of the transmission line 25 is expressed by Expression (19).

From Expression (19), the electrical length E of the transmission line 25 can be obtained from the imaginary component Im (Z _doff ) of the impedance Z _doff of the diode element 3 when the reverse voltage is applied. If the electrical length E of the transmission line 25 is expressed by Equation (19) in a desired frequency band, the rectifier circuit 10 in the present embodiment is in series resonance and can be short-circuited. That is, the reactance component of the series body including the diode element 3 and the transmission line 25 resonates in series. Here, the desired frequency band is the frequency band of the high-frequency signal input to the rectifier circuit 10.
On the other hand, the impedance Z _dnewon at the time of forward voltage is expressed by equation (20) from equation (15).

  Assuming that the resistance component of the diode element 3 at the forward voltage is sufficiently small, the equation (20) becomes the equation (21).

It can be seen that the frequency characteristic of the impedance Z _dnewon depends on the imaginary component in the equation (21), that is, the transmission line 25. Here, if the frequency of the input signal is f ₀ , and the frequency at which the transmission line 25 has a quarter wavelength is f ₁ , the electrical length is expressed by Expression (22).

Here, v is a phase velocity. When the frequency is f _{1 , the} transmission line 25 has a quarter wavelength, and thus the line length l of the transmission line 25 is expressed by Expression (23).

Therefore, the relational expression between the frequency f ₁ and the frequency f ₀ is expressed by Expression (24).

When a forward voltage is applied to the diode element 3 from the equation (24), if the diode element 3 having a sufficiently small C _j whose electrical length E approaches 90 degrees is selected, a high impedance can be obtained at the frequency f ₁ . Therefore, when C _j is sufficiently small, the impedance Z _dnewon is expressed by the equation (25) and becomes high impedance, that is, open.

Next, a description will be given frequency dependence of the electrical length E of the transmission line 25 to the imaginary component of the impedance Z _d is zero.
3, (19) is a diagram showing the frequency dependence of the electrical length E of the transmission line 25 to the imaginary component to zero impedance Z _d calculated from the equation, the horizontal axis represents the frequency (GHz), the longitudinal axis Indicates the electrical length (degree). As shown in FIG. 3, the electrical length when the frequency is 2 GHz is 78.6 degrees.

FIG. 4 shows an imaginary component of the impedance Z _dnew calculated using this value.
FIG. 4 shows the calculation results when the circle is R _doff = 1000 ohm (ohm = Ω) and the circle painted black is R _don = 10 ohm. As shown in FIG. 4, the imaginary component of the impedance Z _dnew when the frequency is 2 GHz and a reverse voltage is applied to the diode element 3 (R _doff = 1000 ohm when round) is zero. That is, the impedance is minimized.
On the other hand, when a forward voltage is applied to the diode element 3 (in the case of a black circle, R _don = 10 ohms), the imaginary component of the impedance is about 300 ohms, and the impedance becomes high as shown in equation (26). I understand.

  Next, the effect in this embodiment is demonstrated using FIG.5, FIG.6, FIG.7. FIG. 5 is a diagram showing a two-terminal circuit in which the transmission line 34 is shunt-connected to the diode element 33 in the present embodiment. FIG. 6 is a diagram showing a two-terminal circuit in which a diode element 43 having a conventional configuration is shunt-connected. FIG. 7 shows the result of calculating the S parameter (transmission characteristic S21) for the two-terminal circuit shown in FIGS. When the value of the S parameter is low, it indicates that the shunt-connected circuit has a high frequency suppression characteristic, and as the S parameter value approaches zero from a negative value, it indicates that the circuit has a high frequency transmission characteristic. In addition, a horizontal axis shows a frequency (GHz) and a vertical axis | shaft shows S parameter (dB).

As shown in FIG. 7, when the reverse voltage is applied to the diode element 33 (R _doff = 1000 ohm) in the structure of the present embodiment, it is round, and when the forward voltage is applied to the diode element (R _don = 10 ohm) is indicated by a black circle.
Further, when the reverse voltage is applied to the diode element 43 in the conventional structure (R _doff = 1000 ohm), the triangle is displayed, and when the forward voltage is applied to the diode element in the conventional structure (R _don = 10 ohm) is black. Shown with painted triangles.

  The conventional structure with only the diode element 43 shows a constant frequency characteristic over the entire frequency band, whereas in the structure of this embodiment, when a reverse voltage is applied to the diode element 33, the set frequency is 2 GHz. The frequency characteristic at which the S parameter is a minimum value is shown. Further, in the structure of this embodiment, when a forward voltage is applied to the diode element 33, the frequency characteristic is such that the set frequency is 2.3 GHz and the S parameter is a maximum value.

  That is, in the structure of this embodiment, when a reverse voltage is applied to the diode element 33 (circle in FIG. 7), the high-frequency signal is the circuit shown in FIG. 5 at a frequency of 2 GHz where the S parameter is a minimum value. Through the ground. On the other hand, when a forward voltage is applied to the diode element 33 (circled in black in FIG. 7), the value of the S parameter in the frequency 2 GHz band is higher than the frequency 2.3 GHz at which the S parameter is a maximum value. Low.

However, the structure of the present embodiment shows higher high-frequency transmission characteristics than when the reverse voltage is applied to the diode element 43 in the conventional structure (triangle in FIG. 7), and is applied to the diode element 33 in this embodiment. It can be seen that the high voltage suppression performance is obtained when the voltage is equal to or lower than the negative forward voltage V ₀ .

Next, the operation principle of the rectifier circuit 10 in this embodiment will be described.
FIG. 8A is an image diagram showing the operation principle of the rectifier circuit 10 in the present embodiment. FIG. 8B is an image diagram showing a voltage change immediately after the high frequency signal is input at point A in FIG. FIG. 8C is an image diagram showing a voltage change in a steady state at the output terminal of FIG.

The input signal (FIG. 8 (a)) is stored in the capacitive element, whereby the DC voltage is boosted. Structure of this embodiment has a high frequency suppression performance in the following forward voltage V _0, the negative peak value of the boosted high frequency signal does not become less than the forward voltage V _0, the forward voltage greater than or equal _to V ₀ (FIG. 8B). The boosted high-frequency signal has the high-frequency component removed by the filter circuit 7 and has the same operation as the ideal operating principle shown in FIG. 13C (FIG. 8C).

Next, FIG. 9 shows a calculation example of the conversion efficiency of the rectifier circuit 10 in this embodiment. In addition, the parameter of the diode element 3 used the general parameter of the diode element marketed. In addition, the specific example of this embodiment and the specific example of the conventional circuit are used for the calculation, and the circle shown in FIG. 9 is the result of the rectifier circuit 10 of this embodiment, and the black triangle is the result of the conventional rectifier circuit.
FIG. 10 is an example of a specific circuit diagram of the rectifier circuit 10 in the present embodiment. FIG. 11 is an example of a specific circuit diagram of a conventional rectifier circuit.

The rectifier circuit shown in FIG. 10 has an input terminal 51 for inputting a high-frequency signal, an output terminal 52 for outputting a DC signal, a diode element 53, transmission lines 54 and 56 to 61, a capacitive element 55, and a load resistor 62. . The input matching circuit 6 shown in FIG. 1 has transmission lines 56-58. The filter circuit 7 has transmission lines 59 to 61.
The conventional high-frequency rectifier circuit shown in FIG. 11 has an input terminal 71 for inputting a high-frequency signal, an output terminal 72 for outputting a DC signal, a diode element 73, transmission lines 76 to 81, a capacitive element 75, and a load resistor 82. Yes. An input matching circuit 96 shown in FIG. 12 has transmission lines 76 to 78. The filter circuit 97 includes transmission lines 79 to 81. As shown in FIG. 9, it can be seen that the rectifier circuit shown in FIG. 10 can achieve a higher efficiency of 5% or more than the conventional circuit.

  As described above, the input terminal 1 for inputting a high frequency signal, the output terminal 2 for outputting a DC signal, the capacitive element 5 having one end connected to the input terminal, and one end connected to the other end of the capacitive element 5 One end (cathode) is connected to the matching circuit 6, the filter circuit 7 having one end connected to the other end of the matching circuit 6 and the other end connected to the output terminal 2, and the connection point between the matching circuit 6 and the filter circuit 7. The rectifier circuit 10 including the diode element 3 further includes a transmission line 4 having one end connected to the other end (anode) of the diode element and the other end grounded, and a predetermined reverse voltage is applied. The parameters of the transmission line 4 are set so that the reactance component of the series body having the current diode element 3 and the transmission line 4 resonates in series at the operating frequency. As a result, a drop in the boosted voltage due to signal leakage from the diode element 3 or the like can be suppressed, and the high-frequency-DC conversion efficiency can be increased. As a result, power can be received wirelessly in a higher frequency band, and the antenna for transmitting and receiving power can be reduced in size. Moreover, it can contribute to size reduction and high efficiency of the wireless power transmission device.

  The above-described embodiments are all illustrative of the embodiments of the present invention and are not limited to the embodiments, and the present invention can be implemented in various other modifications and changes.

1, 11, 21, 31, 41, 51, 71, 91, 101, 111 Input terminals 2, 12, 22, 32, 42, 52, 72, 92, 102, 112 Output terminals 3, 33, 43, 53, 73, 93 Diode element 4, 25, 34, 54, 56-61, 76-81 Transmission line 5, 14, 24, 65, 75, 95 Capacitance element 6, 96 Input matching circuit 7, 97 Filter circuit 13, 23 Resistance Elements 62 and 82 Load resistance 103 Junction resistance 104 Junction capacity 105 Contact resistance 106 Parasitic capacity 113 Resistance element 114 Capacitance element

Claims (2)

An input terminal for inputting a high-frequency signal;
A capacitive element having one end connected to the input terminal;
A matching circuit having one end connected to the other end of the capacitive element;
A diode element having a cathode connected to the other end of the matching circuit;
A filter circuit connected to the other end of the matching circuit;
A transmission line having one end connected to the anode of the diode element and the other end grounded;
An output terminal from which the other end of the filter circuit outputs a DC signal;
With
A high-frequency rectifier circuit, wherein a reactance component of a series body including the diode element and the transmission line resonates in series at a use frequency when a predetermined voltage is applied to the diode element in a reverse direction. Electrical length E of the transmission line, the impedance of the reverse voltage is applied the diode element Z _doff, the characteristic impedance of the transmission line as Z _c, that of the formula shown in hereinafter by the use frequency The high-frequency rectifier circuit according to claim 1, wherein

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