CN115483889A - Millimeter wave injection locking frequency doubler - Google Patents

Abstract

The invention discloses a millimeter wave injection locking frequency doubler, which comprises a complementary push-push frequency doubler circuit and an injection locking oscillator. The complementary push-push frequency doubler circuit is used for generating harmonic signals with double frequency, the injection locking oscillator is used for locking the harmonic generated by the complementary push-push frequency doubler circuit, and the complementary push-push frequency doubler circuit is directly coupled and connected with the injection locking oscillator; the input fundamental wave signal generates harmonic component through a complementary push-push frequency doubler circuit, and then is directly coupled with an injection locking oscillator to realize frequency doubling. Compared with the traditional frequency multiplier structure, the invention has wider locking range when the input power is smaller, and has the advantages of low input sensitivity, low power consumption, high integration and the like.

Description

A Millimeter-Wave Injection-Locked Frequency Doubler

technical field

The invention relates to the technical field of radio frequency integration, in particular to a millimeter wave injection-locked frequency doubler applied to a frequency synthesizer.

Background technique

The frequency multiplier plays an extremely important role in a phase locked loop (PLL), and is also a key circuit in a wireless communication system. At present, most of the millimeter-wave phase-locked loops use a low-frequency phase-locked loop cascaded with a frequency multiplier. In this way, the phase noise and power consumption of the local oscillator have a good compromise, and at the same time, the frequency doubler can also avoid the injection-pulling phenomenon of the oscillator resonant cavity. The locking range of the traditional frequency multiplier is relatively narrow, generally around 8%, which makes its application range very limited. The main methods to achieve a wide locking range are to reduce the Q value of the LC resonant cavity and increase the injection efficiency of the second harmonic, but reducing the Q value of the LC resonant cavity will reduce the parallel resistance of the resonant cavity, so that the negative resistance needs to be increased tube size, increasing power dissipation. However, increasing the injection efficiency of the second harmonic needs to optimize the injection stage circuit separately, which makes the circuit structure complicated. Therefore, expanding the frequency division range of the injection-locked doubler is one of the important conditions for designing a high-quality high-frequency doubler.

The document "M.C.Chen and C.Y.Wu.Design and analysis of CMOS subharmonic injection-locked frequency triplers.IEEE Transactions on Microwave Theory and Techniques[J],2008,56(8):1869–1878." adopts the structure of MOS direct injection, by MOS The tube is directly injected into the resonant cavity, and its drain generates high-order harmonic pull and locks the resonant cavity frequency. Although this method of direct injection using a MOS tube has a simple structure, it requires a huge power consumption, and the injection tube cannot be optimized, so that the injection signal cannot be increased, and thus the locking range cannot be increased.

Document "H.Jia and L.Kuang."A W-Band Injection-Locked Frequency DoublerBased on Top-Injected Coupled Resonator[J].In:2016IEEE Transactions on Microwave Theory and Techniques.210–218." The W-band injection-locked frequency multiplier is realized by means of a W-band injection. The second harmonic current is injected from the top, although the problem of source-level degradation is avoided, but the circuit design is relatively complicated and requires a high Q value, which increases to a certain extent The power consumption of the circuit is reduced and the locking range of the circuit cannot be further increased.

Contents of the invention

Purpose of the invention: The present invention aims at the problems existing in the prior art, and provides a millimeter-wave injection-locked frequency doubler with a wide range, so as to solve the problem that the injection-locked doubler structure of the prior art has a relatively small locking range.

Technical solution: In order to achieve the purpose of the above invention, a millimeter-wave injection-locked frequency doubler with a wide range of the present invention includes two parts: a complementary push-push double frequency generation circuit and an injection-locked oscillator, and a complementary push-push two The frequency multiplication generating circuit is directly coupled with the injection-locked oscillator; the injected fundamental wave signal is injected through the complementary push-push double frequency generating circuit and the positive and negative input terminals of the injection-locked oscillator, and the injected fundamental wave signal is injected through the complementary push-push The double frequency generating circuit generates a harmonic component, and then directly couples to the injection locked oscillator, and the injection locked oscillator locks the harmonic signal generated by the complementary push-push double frequency generating circuit to generate a double frequency output signal.

The complementary push-push double frequency generation circuit includes a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; the first MOS tube and the second MOS tube The gate of the tube is connected to the negative input terminal, the gates of the third MOS tube and the fourth MOS tube are connected to the positive input terminal; the drains of the first MOS tube and the fourth MOS tube are connected to one end of the first inductor, the second MOS tube and the The drain of the third MOS transistor is connected to the other end of the first inductor; the sources of the first MOS transistor and the fourth MOS transistor are connected to the gate of the sixth MOS transistor, and the sources of the second MOS transistor and the third MOS transistor are connected to the first MOS transistor. The gate of the five MOS transistors.

The complementary push-push double frequency generation circuit samples a completely symmetrical structure, so the signal voltage swings of the source and drain of the first MOS transistor can be roughly equal.

The injection-locked oscillator is composed of a first inductor, a first adjustable capacitor, a second adjustable capacitor, a tuning voltage, a seventh MOS transistor, and an eighth MOS transistor; the drain of the seventh MOS transistor and the drain of the eighth MOS transistor The drains are respectively connected to the first adjustable capacitor and the second adjustable capacitor; the gate of the eighth MOS transistor is connected to the drain of the seventh MOS transistor, and the gate of the seventh MOS transistor is connected to the drain of the eighth MOS transistor ; The sources of the seventh MOS transistor and the eighth MOS transistor are both connected to the ground, wherein the seventh MOS transistor and the eighth MOS transistor are used for negative resistance compensation.

For the injection-locked oscillator, when the injection-locked oscillator is locked and the phase of the injection-locked oscillator at this frequency point is not zero, the complementary push-push double frequency generation circuit of the external circuit must provide enough phase to compensate for the incoming injection-locked oscillator. The phase difference between the total oscillator current and the injection-locked oscillator free current that causes locking to occur; the phase difference between the total current flowing into the injection-locked oscillator and the injection-locked oscillator free current is related to the phase of the injection-locked oscillator impedance, Therefore, adjusting the injection-locked oscillator to make the impedance of the injection-locked oscillator flat enough can widen the locking range of the injection-locked frequency doubler.

In the injection-locked oscillator, the total current flowing into the injection-locked oscillator can be regarded as a vector sum of the free-running current of the injection-locked oscillator and the injected current, and the angle between the vector total current and the free current of the injection-locked oscillator That is, the phase of the input impedance of the injection-locked oscillator; under the injection signal of fixed power, the current generated by the complementary push-push double frequency circuit is a fixed value, and the current generated by the free current of the injection locked oscillator and the complementary push-push double frequency circuit The maximum angle of the total current of current synthesis determines the locking range; increasing the external injection signal power of the injection-locked oscillator can widen the operating bandwidth of the injection-locked oscillator, and increase the injected signal power through direct coupling.

The output signal frequency is twice the frequency of the injected fundamental wave signal.

Beneficial effects: Compared with the prior art, the present invention has a wide range of millimeter-wave injection-locked frequency doublers, and its beneficial effects are:

1. It solves the problem that the traditional injection-locked frequency multiplier has a narrow locking range when the input power is small, and provides a millimeter-wave injection-locked frequency multiplier with low input sensitivity, so that the frequency multiplier still has a low input power. Wide locking range;

2. The present invention uses MOS transistors to provide additional phase compensation. Under a given frequency offset, the injection-locked frequency doubler will work away from the locking edge, and the power of the injected signal is increased through direct coupling. Thereby, the locking range is expanded, and an ultra-wide range of locking can be realized.

Description of drawings

Figure 1 is a schematic diagram of the basic injection locking circuit;

Fig. 2 is the current vector synthesis diagram of the LC resonant cavity;

Fig. 3 is the schematic diagram of complementary pushing-push double frequency circuit of the present invention;

Fig. 4 is a millimeter wave injection-locked frequency multiplier with a wide locking range according to the present invention.

In the figure, there are: the first inductor L1, the first MOS transistor M1, the second MOS transistor M2, the first adjustable capacitor C1; the second inductor L2, the second inductor L3, the second adjustable capacitor C2, and the third MOS transistor M3 , fourth MOS transistor M4, fifth MOS transistor M5, sixth MOS transistor M6, seventh MOS transistor M7, eighth MOS transistor M8, first resistor R1, second resistor R2, third capacitor C3, fourth capacitor C4. Positive input terminal f _in+ , negative input terminal f _in- , positive output terminal f _out+ , negative output terminal f _out- , power supply voltage VDD.

detailed description

The technical solutions of the present invention will be described in detail below in conjunction with specific implementation methods and accompanying drawings.

As shown in Figure 1, the schematic diagram of the basic injection locking circuit, its circuit structure includes: L ₁ and C ₁ represent the inductance and capacitance of the resonant cavity, R _P is the parasitic resistance of L ₁ , and the current source I _inj represents the external injection into the resonant cavity The signal (double frequency signal), I _osc represents the free resonant current, _{IT is the vector superposition of I inj and} I _osc , ω _inj is the frequency of the external signal injected into the resonant cavity.

为矢量I_T与矢量I_osc间的角度，θ为矢量I_inj与矢量I_osc间的角度。在固定功率的注入信号下，||I_inj||为固定数值，I_osc与I_inj合成的I_T的最大角度决定了锁定范围。因此，增大注入信号功率可以加宽注入锁定二倍频器工作带宽。锁定范围表达式如下：As shown in Figure 2, the current vector synthesis diagram of the LC resonant cavity, its circuit structure includes: the external signal I _inj injected into the resonant cavity, the free resonant current I _osc , _IT is the vector superposition of the above two currents,

is the angle between the vector I _T and the vector I _osc , and θ is the angle between the vector I _inj and the vector I _osc . Under the injection signal of fixed power, ||I _inj || is a fixed value, and the maximum angle of I _T synthesized by I _osc and I _inj determines the locking range. Therefore, increasing the injected signal power can widen the operating bandwidth of the injection-locked frequency doubler. The locked range expression is as follows:

Among them, ω ₀ is the free oscillation frequency of the injection-locked oscillator, and Q is the Q value corresponding to the LRC network, where the Q value can reflect the phase-frequency characteristic.

As shown in Figures 3 and 4, a millimeter-wave injection-locked frequency doubler with a wide locking range of the present invention has a circuit structure comprising: a complementary push-push double frequency generation circuit 1, an injection-locked oscillator 2 and Output buffer stage 3.

The complementary push-push double frequency generation circuit 1 is directly coupled with the injection locked oscillator 2; the injected fundamental wave signal passes through the complementary push-push double frequency generation circuit 1 and the positive input terminal fin ₊ and the negative input terminal of the injection locked oscillator 2 _Fin -injection, the injected fundamental wave signal generates harmonic components through the complementary push-push double frequency generation circuit 1, and then directly coupled to the injection locked oscillator 2, and the injection locked oscillator 2 locks the complementary push-push double frequency generation circuit The harmonic signal generated by 1 produces a multiplied output signal. The complementary push-push double frequency circuit 1 is used to generate a double frequency harmonic signal, and the injection locked oscillator is used to lock the harmonic signal generated by the harmonic generator. The injected complementary push-push doubler circuit 1 generates harmonic components, which are then coupled directly to an injection-locked oscillator 2 for frequency doubling. The complementary push-push double frequency generating circuit 1 includes a first MOS transistor M1, a second MOS transistor M2, a third MOS transistor M3 and a fourth MOS transistor M4, the gate of the first MOS transistor M1 and the gate of the third MOS transistor M3 The gate is connected to the negative input terminal _fin- , and the gates of the second MOS transistor M2 and the fourth MOS transistor M4 are connected to the positive input terminal fin ₊ . The drains of the first MOS transistor M1 and the fourth MOS transistor M4 output the second harmonic component of the preset frequency.

The injection locked oscillator 2 includes a first coupling inductor L1, a first capacitor C1, a second capacitor C2, a seventh MOS transistor M7, and an eighth MOS transistor M8. Wherein the seventh MOS transistor M7 and the eighth MOS transistor M8 are used for negative resistance compensation. When the resonator is locked and the phase of the resonator at this frequency point is not zero, the external circuit (i.e., the complementary push-push double frequency generating circuit) must provide enough phase to compensate the difference between the total current flowing into the resonator and the free resonator current phase difference so that locking occurs. According to vector analysis, it is easy to know that the phase difference between the total current flowing into the resonant cavity and the free resonant cavity current is related to the phase of the resonant cavity impedance, so adjusting the resonant cavity to make the resonant cavity impedance flat enough can widen the locking of the injection-locked doubler scope.

The total current flowing into the resonant cavity can be regarded as the vector addition of the free oscillation current of the oscillator and the injected current, and the angle between the total vector current and the free resonant cavity current is the phase of the input impedance of the LC resonant cavity. Under the injection signal of fixed power, the current generated by the complementary push-push double frequency circuit is a fixed value, and the maximum angle of the total current synthesized by the free resonant cavity current and the current generated by the complementary push-push double frequency circuit determines the locking scope. Therefore, increasing the injected signal power can widen the operating bandwidth of the injection-locked frequency doubler. Therefore, the design is also based on this idea, and the injected signal power is increased through direct coupling.

The complementary push-push double frequency generating circuit 1 of this embodiment includes: a first MOS transistor M1, a second MOS transistor M2, a third MOS transistor M3, and a fourth MOS transistor M4. The harmonic generating circuit generates the second harmonic signal at the drains of the first MOS transistor M1 and the fourth MOS transistor M4 by utilizing the nonlinearity of the first MOS transistor M1 and the fourth MOS transistor M4 from the input fundamental frequency signal, and passes through the capacitor DC blocking effect, the drain current I _d (t) of the first MOS transistor M1 can be expressed as the following form

Among them, ω _INJ is the frequency of the injected signal, k _n = μ _n C _ox w _n /l _n and k _p = μ _p C _ox w _p /l _p , C _OX is the gate capacitance per unit area, w _n /l _n and w _p /l _p are the width-to-length ratios of the NMOS and PMOS tubes, respectively, μ _n and μ _p are the mobility of electrons and holes, respectively, and A is the amplitude of the differential input signal.

As stated above, while the invention has been shown and described with reference to certain preferred embodiments, this should not be construed as limiting the invention itself. Various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (7)

1. A millimeter wave injection locking frequency doubler is characterized by comprising a complementary push-push frequency doubler generating circuit (1) and an injection locking oscillator (2), wherein the complementary push-push frequency doubler generating circuit (1) is directly coupled with the injection locking oscillator (2); the injected fundamental wave signal passes through the complementary push-push double frequency generation circuit (1) and the positive input end (f) of the injection locked oscillator (2) _in+ ) And a negative input terminal (f) _in- ) And injecting, wherein the injected fundamental wave signal generates a harmonic component through the complementary push-push double-frequency generation circuit (1) and then is directly coupled to the injection locking oscillator (2), and the injection locking oscillator (2) locks the harmonic signal generated by the complementary push-push double-frequency generation circuit (1) to generate a frequency multiplication output signal.

2. The millimeter wave injection locking frequency doubler according to claim 1, wherein the complementary push-push frequency doubler generating circuit (1) comprises a first MOS transistor (M1), a second MOS transistor (M2), a third MOS transistor (M3), a fourth MOS transistor (M4), a fifth MOS transistor (M5) and a sixth MOS transistor (M6); the grids of the first MOS transistor (M1) and the second MOS transistor (M2) are connected with the negative input end (f) _in- ) The grids of the third MOS transistor (M3) and the fourth MOS transistor (M4) are connected with the positive input end (f) _in+ ) (ii) a The drain electrodes of the first MOS transistor (M1) and the fourth MOS transistor (M4) are connected with a first electrodeOne end of the inductor (L1), drain electrodes of the second MOS tube (M2) and the third MOS tube (M3) are connected with the other end of the first inductor (L1); the source electrodes of the first MOS transistor (M1) and the fourth MOS transistor (M4) are connected with the grid electrode of the sixth MOS transistor (M6), and the source electrodes of the second MOS transistor (M2) and the third MOS transistor (M3) are connected with the grid electrode of the fifth MOS transistor (M5).

3. The millimeter wave injection-locked frequency doubler according to claim 2, wherein the complementary push-push frequency doubler generating circuit (1) has a completely symmetrical structure, so that the signal voltage swings of the source and drain of the first MOS transistor (M1) are substantially equal.

4. The millimeter wave injection-locked frequency doubler according to claim 1, wherein the injection-locked oscillator (2) is composed of a first inductor (L1), a first adjustable capacitor (C1), a second adjustable capacitor (C2), and a tuning voltage (V |) _tune ) The seventh MOS tube (M7) and the eighth MOS tube (M8); the drain electrode of the seventh MOS tube (M7) and the drain electrode of the eighth MOS tube (M8) are respectively connected with the first adjustable capacitor (C1) and the second adjustable capacitor (C2); the grid electrode of the eighth MOS tube (M8) is connected with the drain electrode of the seventh MOS tube (M7), and the grid electrode of the seventh MOS tube (M7) is connected with the drain electrode of the eighth MOS tube (M8); the source electrodes of the seventh MOS tube (M7) and the eighth MOS tube (M8) are both connected with the Ground (GND), wherein the seventh MOS tube (M7) and the eighth MOS tube (M8) are used for negative resistance compensation.

5. The millimeter wave injection-locked frequency doubler according to claim 4, wherein the injection-locked oscillator (2) is configured such that when the injection-locked oscillator is locked and the phase of the injection-locked oscillator at the frequency point is not zero, the complementary push-push frequency doubler generating circuit (1) of the external circuit must provide sufficient phase to compensate for the phase difference between the total current flowing into the injection-locked oscillator and the free current of the injection-locked oscillator, so that locking occurs; the phase difference between the total current flowing into the injection locked oscillator and the free current of the injection locked oscillator is related to the phase of the injection locked oscillator impedance, so adjusting the injection locked oscillator so that the injection locked oscillator impedance is flat enough can widen the locking range of the injection locked doubler.

6. The millimeter wave injection-locked frequency doubler according to claim 5, wherein the total current flowing into the injection-locked oscillator (2) is regarded as a sum of a free oscillation current of the injection-locked oscillator and an injection current vector, and an angle between the vector total current and the free current of the injection-locked oscillator is a phase of an input impedance of the injection-locked oscillator; under the injection signal of fixed power, the current generated by the complementary push-push frequency doubling circuit is a fixed value, and the maximum angle of the total current synthesized by the free current of the injection locking oscillator and the current generated by the complementary push-push frequency doubling circuit determines the locking range; the working bandwidth of the injection locking oscillator can be widened by increasing the external injection signal power of the injection locking oscillator, and the injection signal power is increased by a direct coupling mode.

7. The millimeter wave injection-locked frequency doubler according to claim 2, wherein the output signal frequency is 2 times the frequency of the injected fundamental signal.

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