A millimeter wave injection-locked tripler

Abstract

The application discloses a kind of millimeter wave injection locking tripler, including two parts of harmonic generator and injection locking oscillator.Harmonic generator is used to generate harmonic signal, and injection locking oscillator is used to lock the harmonic generated by harmonic generator, and harmonic generator is connected with injection locking oscillator by transformer coupling.Compared with the structure of conventional frequency multiplier, the application still has a wide locking range when the input power is small, and has the advantages of ultra-wide bandwidth, low input sensitivity, low power consumption, high integration and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of radio frequency integrated technology, and particularly relates to a millimeter wave injection-locked tripler applied to a frequency synthesizer. BACKGROUND

[0002] The frequency tripler 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 millimeter wave phase locked loops adopt a low-frequency phase locked loop cascaded with a frequency tripler. In this way, the phase noise and power consumption of the local oscillator can be well compromised, and the injection pulling phenomenon of the resonant cavity of the oscillator can also be avoided. The locking range of the conventional frequency tripler is relatively narrow, generally about 8%, which limits the application range. The methods for realizing a wide locking range mainly include reducing the Q value of the LC resonant cavity and increasing the injection efficiency of the third harmonic, but reducing the Q value of the LC resonant cavity will reduce the parallel resistance value of the resonant cavity, thereby the size of the negative resistance tube needs to be increased, and the power consumption is also increased. Increasing the injection efficiency of the third harmonic needs to optimize the injection stage circuit separately, which makes the circuit structure complex. Therefore, expanding the frequency division range of the injection-locked tripler is one of the important conditions for designing a high-quality high-frequency frequency tripler.

[0003] 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 a MOS direct injection structure, in which the MOS tube directly injects into the resonant cavity, and the drain generates a high-order harmonic to pull and lock the frequency of the resonant cavity. Although this direct injection method using the MOS tube has a simple structure, it needs a large 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.

[0004] Document "Z. Chen and P. Heydari. An 85-95.2GHz transformer-based injection-locked frequency tripler in 65-nm CMOS [C]. In: 2010 IEEE MTT-S International Microwave Symposium. 776-779." uses a transformer coupling structure to realize an injection-locked frequency tripler. The DC path of the injection MOS tube is separated from the source node of the cross-coupled pair by the transformer, so the injection MOS tube can be biased to maximize the third harmonic. The transformer also reduces the impedance seen by the source node of the cross-coupled pair, but the transformer at the source stage of the cross-coupled tube can cause the source stage to degenerate, thereby narrowing the locking range. SUMMARY

[0005] The present application provides a millimeter wave injection-locked frequency tripler to solve the problem of small locking range of the injection-locked frequency tripler structure.

[0006] Technical scheme: To achieve the above-mentioned application purpose, the millimeter wave injection-locked frequency tripler of the present application comprises two parts of a harmonic generator and an injection-locked oscillator, and the harmonic generator and the injection-locked oscillator are connected through transformer coupling; the injection base wave signal is injected through the positive input end and the negative input end of the harmonic generator and the injection-locked oscillator, the injection base wave signal generates harmonic components through the harmonic generator, and then is coupled to the injection-locked oscillator through the transformer, the injection-locked oscillator locks the harmonic signal generated by the harmonic generator to generate a frequency multiplication output signal; the transformer is composed of a first coupling inductance included in the harmonic generator and a second coupling inductance included in the injection-locked oscillator, and the coupling coefficient between the first coupling inductance and the second coupling inductance is adjusted to widen the bandwidth of the frequency multiplier.

[0007] Wherein,

[0008] The harmonic generator comprises a first MOS tube and a second MOS tube, a first coupling inductance and a first capacitor; the specific connection structure is that the gate of the first MOS tube is connected to the positive input end, the gate of the second MOS tube is connected to the negative input end, the source of the first MOS tube is connected to the power supply, the source of the second MOS tube is connected to the ground, the drain of the first MOS tube is connected to one end of the first coupling inductance and one end of the first capacitor, and the drain of the second MOS tube is connected to the other end of the first coupling inductance and the other end of the first capacitor.

[0009] The first capacitor is one or a combination of the parasitic capacitance of the first coupling inductance, the parasitic capacitance of the harmonic generator output end, the parasitic capacitance of the first MOS tube and the second MOS tube, and the adjustable capacitor.

[0010] The gate of the first MOS tube and the gate of the second MOS tube in the harmonic generator inject a fundamental wave signal through the positive input end and the negative input end, so that the first MOS tube and the second MOS tube are biased in the weak inversion region, and the drain of the first MOS tube and the drain of the second MOS tube output the third harmonic component of the fundamental wave signal.

[0011] The injection-locked oscillator comprises a second coupling inductor, a second capacitor, a current source, a third MOS tube, a fourth MOS tube, a fifth MOS tube, a sixth MOS tube, a first resistor, a second resistor, a third capacitor, a fourth capacitor and a voltage source.

[0012] The second capacitor is a combination of one or more of the parasitic capacitance of the second coupling inductor, the parasitic capacitance of the third MOS tube and the fourth MOS tube, and the adjustable capacitor.

[0013] The gate of the fifth MOS tube and the gate of the sixth MOS tube in the injection-locked oscillator inject a fundamental wave signal through the third capacitor and the fourth capacitor, respectively, so that the fifth MOS tube and the sixth MOS tube provide additional phase compensation and improve the locking range of the millimeter wave injection-locked tripler.

[0014] The frequency of the output signal is 3 times the frequency of the injected fundamental wave signal.

[0015] Advantages: Compared with the prior art, the present application has the following advantages:

[0016] 1. The problem of narrow locking range of the traditional injection-locked frequency multiplier at low input power is solved, and a millimeter wave injection-locked frequency multiplier with low input sensitivity is provided, so that the frequency multiplier still has a wide locking range at low input power.

[0017] 2、The present application provides additional phase compensation by using MOS tube, under given frequency offset, the injection locking tripler will work far from the locking edge, thus expanding the locking range. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the circuit schematic of the injection locking tripler of the present application;

[0019] Figure 2 is the simplified model of the injection locking tripler of the present application.

[0020] The figure has: first coupling inductance L1, first MOS tube M1, second MOS tube M2, first capacitor C1; second coupling inductance L2, second capacitor C2, third MOS tube M3, fourth MOS tube M4, current source I bias , fifth MOS tube M5, sixth MOS tube M6, first resistor R1, second resistor R2, third capacitor C3, fourth capacitor C4, voltage source V bias ; positive input end INP, negative input end INN, positive output end OUTP, negative output end OUTN, power supply voltage VDD. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described in detail below in combination with specific embodiments and drawings.

[0022] As Figure 1 shown, the millimeter wave injection locking tripler of the present application has a circuit structure including a harmonic generator 1 and an injection locking oscillator 2. The harmonic generator 1 and the injection locking oscillator 2 are connected through a transformer coupling. The injection base wave signal is injected through the positive input end INP and the negative input end INN of the harmonic generator 1 and the injection locking oscillator 2, the injection base wave signal generates harmonic components through the harmonic generator 1, and then is coupled to the injection locking oscillator 2 through the transformer, the injection locking oscillator 2 locks the harmonic signal generated by the harmonic generator, and generates a frequency multiplication output signal. The transformer is composed of the first coupling inductance L1 included in the harmonic generator 1 and the second coupling inductance L2 included in the injection locking oscillator 2, and the coupling coefficient between the first coupling inductance L1 and the second coupling inductance L2 is adjusted to broaden the bandwidth of the frequency multiplier.

[0023] The harmonic generator 1 includes a first MOSFET M1 and a second MOSFET M2, a first coupling inductor L1, and a first capacitor C1. The gate of the first MOSFET M1 is connected to the positive input terminal INP, the gate of the second MOSFET M2 is connected to the negative input terminal INN, the source of the first MOSFET M1 is connected to the power supply, the source of the second MOSFET M2 is grounded, the drain of the first MOSFET M1 is connected to one end of the first coupling inductor L1 and one end of the first capacitor C1, and the drain of the second MOSFET M2 is connected to the other end of the first coupling inductor L1 and the other end of the first capacitor C1.

[0024] Among them, the first capacitor C1 is a combination of one or more of the parasitic capacitance of the first coupling inductor L1, the parasitic capacitance of the output terminal of the harmonic generator, the parasitic capacitance of the first MOSFET M1 and the second MOSFET M2, and an adjustable capacitor.

[0025] A fundamental frequency signal of a preset frequency is injected into the gate of the first MOSFET M1 and the gate of the second MOSFET M2, so that when the first MOSFET M1 and the second MOSFET M2 are biased in the weak inversion region, the drain of the first MOSFET M1 and the second MOSFET M2 outputs the third harmonic component of the preset frequency.

[0026] Injection-locked oscillator 2 includes a second coupling inductor L2, a second capacitor C2, a third MOSFET M3, a fourth MOSFET M4, and a current source I. bias Fifth MOSFET M5, sixth MOSFET M6, first resistor R1, second resistor R2, third capacitor C3, fourth capacitor C4, voltage source V bias The center tap of the second coupling inductor L2 is connected to one end of a current source, I. bias The other end is connected to the power supply. One end of the second coupling inductor L2 is connected to the drain of the third MOSFET M3, the gate of the fourth MOSFET M4, one end of the second capacitor C2, and the positive output terminal OUTP. The other end of the second coupling inductor L2 is connected to the drain of the fourth MOSFET M4, the gate of the third MOSFET M3, the other end of the second capacitor C2, and the negative output terminal OUTN. The source of the third MOSFET M3 is connected to the drain of the fifth MOSFET M5. The source of the fourth MOSFET M4 is connected to the drain of the sixth MOSFET M6. The gate of the fifth MOSFET M5 is connected to one end of the first resistor R1 and one end of the third capacitor C3. The other end of the first resistor R1 is connected to the voltage source V. bias The other end of the third capacitor C3 is connected to the positive input terminal INP. The gate of the sixth MOSFET M6 is connected to one end of the second resistor R2 and one end of the fourth capacitor C4. The other end of the second resistor R2 is connected to the voltage source V. bias The other end of the fourth capacitor C4 is connected to the negative input terminal INN, and the drain of the fifth MOSFET M5 and the source of the sixth MOSFET M6 are grounded.

[0027] The second capacitor C2 is a combination of one or more of the parasitic capacitance of the second coupling inductor L2, the parasitic capacitance of the third MOS tube M3 and the fourth MOS tube M4, and the adjustable capacitor.

[0028] The gate of the fifth MOS tube M5 and the gate of the sixth MOS tube M6 are injected with a base wave signal of a preset frequency, so that the fifth MOS tube M5 and the sixth MOS tube M6 provide additional phase compensation, and the locking range of the millimeter wave injection-locked tripler is improved.

[0029] The harmonic generator 1 of the embodiment generates a third harmonic signal at the drain of the first MOS tube M1 and the second MOS tube M2 using the nonlinearity of the first MOS tube M1 and the second MOS tube M2, and injects the generated third harmonic signal into the injection-locked oscillator 2 through a transformer. The drain current I d (t) can be expressed in the form as follows

[0030] I d (t) = I0 + I1cos(ω INJ t) + I2cos(2ω INJ t) + … + I n cos(nω INJ t) (1)

[0031] Where ω INJ is the frequency of the injection signal;

[0032] When n≥1, each coefficient I n can be expressed as

[0033]

[0034] Where I max is the maximum peak-to-peak current output by the transistor drain, T is the period of the injection signal, and t0 is the conduction time of the first MOS tube M1 within one period of the injection signal.

[0035] When n=3 and t0 / T=0.2, I n / I max has a maximum value, that is, when the conduction angle θ of the first MOS tube M1 is 72°, the third harmonic generation efficiency is the highest. Therefore, the present application can optimize the harmonic generation circuit alone, increase the injected harmonic signal, and thus widen the locking range.

[0036] The simplified model of the injection-locked oscillator 2 of the embodiment is shown in Figure 2 In order to simulate the proposed injection-locked tripler, i' INJ is the signal injected by the harmonic generator into the resonant cavity through the transformer. Figure 1The sixth MOS transistor M6 in the figure is equivalent to Figure 2 The signal V inj injected by the signal V T injected by the signal V osc injected by the signal V INJ injected by the signal V osc injected by the signal V T injected by the signal V T injected by the signal V INJ injected by the signal V OSC injected by the signal V

[0037] injected by the signal V OSC injected by the signal V dc injected by the signal V m injected by the signal V osc injected by the signal V INJ injected by the signal V

[0038] injected by the signal V dc injected by the signal V m injected by the signal V inj injected by the signal V

[0039]

[0040] injected by the signal V m injected by the signal V d injected by the signal V ov injected by the signal V dc injected by the signal V ov injected by the signal V d injected by the signal V ov injected by the signal V

[0041]

[0042] injected by the signal V INJ injected by the signal V

[0043] injected by the signal V OSC injected by the signal V T injected by the signal V OSC injected by the signal V INJ injected by the signal V

[0044] The embodiment changes the original injection locking oscillator structure, replaces the original single inductor oscillator structure with two coupled resonant cavities, and adds a stable current source. The resonant cavities in the embodiment make the output impedance of the oscillator smooth due to the addition of the coupling inductor, thus widening the frequency locking range. The oscillator in the embodiment adds a MOS tube that functions as a switch at the source of the negative resistance tube, uses the MOS tube to provide additional phase compensation, and makes the injection locking tripler work far from the locking edge at a given frequency offset, thus expanding the locking range. Compared with the traditional frequency divider, the embodiment adds a current source that provides a stable and continuous current to the injection locking oscillator to maintain the normal operation of the injection locking tripler.

[0045] As described above, although the present application has been described and expressed with reference to specific preferred embodiments, it should not be construed as limiting the present application itself. Various changes can be made in form and details without departing from the spirit and scope of the present application defined by the appended claims.

Claims

1. A millimeter wave injection-locked tripler, characterized by, The frequency multiplier comprises a harmonic generator (1) and an injection locking oscillator (2), the harmonic generator (1) is connected to the injection locking oscillator (2) through transformer coupling, a fundamental wave signal is injected through positive input end (INP) and negative input end (INN) of the harmonic generator (1) and the injection locking oscillator (2), the harmonic component is generated by the harmonic generator (1) through the injected fundamental wave signal, and then the harmonic component is coupled to the injection locking oscillator (2) through the transformer, the injection locking oscillator (2) locks the harmonic signal generated by the harmonic generator, and a frequency multiplication output signal is generated; the transformer is composed of a first coupling inductor (L1) included in the harmonic generator (1) and a second coupling inductor (L2) included in the injection locking oscillator (2), and the coupling coefficient between the first coupling inductor (L1) and the second coupling inductor (L2) is adjusted to widen the bandwidth of the frequency multiplier. The harmonic generator (1) comprises a first MOS tube (M1), a second MOS tube (M2), a first coupling inductor (L1) and a first capacitor (C1), and the specific connection structure is that the gate of the first MOS tube (M1) is connected to the positive input end (INP), the gate of the second MOS tube (M2) is connected to the negative input end (INN), the source of the first MOS tube (M1) is connected to a power supply, the source of the second MOS tube (M2) is connected to the ground, the drain of the first MOS tube (M1) is connected to one end of the first coupling inductor (L1) and one end of the first capacitor (C1), and the drain of the second MOS tube (M2) is connected to the other end of the first coupling inductor (L1) and the other end of the first capacitor (C1). The injection locking oscillator (2) comprises a second coupling inductor (L2), a second capacitor (C2), a current source (I bias ), a third MOS tube (M3), a fourth MOS tube (M4), a fifth MOS tube (M5), a sixth MOS tube (M6), a first resistor (R1), a second resistor (R2), a third capacitor (C3), a fourth capacitor (C4), a voltage source (V bias ). The specific connection structure is as follows: one end of the center tap of the second coupling inductor (L2) is connected to one end of the current source (I bias ), the other end of the current source (I bias ) is connected to a power supply, one end of the second coupling inductor (L2) is connected to the drain of the third MOS tube (M3), the gate of the fourth MOS tube (M4), one end of the second capacitor (C2) and a positive output end (OUTP), the other end of the second coupling inductor (L2) is connected to the drain of the fourth MOS tube (M4), the gate of the third MOS tube (M3), the other end of the second capacitor (C2) and a negative output end (OUTN); the source of the third MOS tube (M3) is connected to the drain of the fifth MOS tube (M5), the source of the fourth MOS tube (M4) is connected to the drain of the sixth MOS tube (M6), the gate of the fifth MOS tube (M5) is connected to one end of the first resistor (R1) and one end of the third capacitor (C3), the other end of the first resistor (R1) is connected to the voltage source (V bias ), the other end of the third capacitor (C3) is connected to a positive input end (INP); the gate of the sixth MOS tube (M6) is connected to one end of the second resistor (R2) and one end of the fourth capacitor (C4), the other end of the second resistor (R2) is connected to the voltage source (V bias ), the other end of the fourth capacitor (C4) is connected to a negative input end (INN), and the drain of the fifth MOS tube (M5) and the source of the sixth MOS tube (M6) are connected to ground. The gate of the fifth MOS tube (M5) and the gate of the sixth MOS tube (M6) in the injection locking oscillator (2) are respectively connected to the third capacitor (C3) and the fourth capacitor (C4) to inject the fundamental wave signal, so that the fifth MOS tube (M5) and the sixth MOS tube (M6) provide additional phase compensation, and the locking range of the millimeter wave injection locking tripler is improved.

2. The millimeter wave injection locked tripler of claim 1, wherein, The first capacitor (C1) is one or a combination of the parasitic capacitor of the first coupling inductor (L1), the parasitic capacitor of the output end of the harmonic generator (1), the parasitic capacitor of the first MOS tube (M1) and the second MOS tube (M2), and an adjustable capacitor.

3. The millimeter wave injection locked tripler of claim 1, wherein, The gate of the first MOS tube (M1) and the gate of the second MOS tube (M2) in the harmonic generator (1) are connected to the positive input end (INP) and the negative input end (INN) to inject the fundamental wave signal, so that when the first MOS tube (M1) and the second MOS tube (M2) are biased in the weak inversion region, the drains of the first MOS tube (M1) and the second MOS tube (M2) output the third harmonic component of the fundamental wave signal.

4. The millimeter wave injection locked tripler of claim 1, wherein, The second capacitor (C2) is one or a combination of the parasitic capacitor of the second coupling inductor (L2), the parasitic capacitor of the third MOS tube (M3) and the fourth MOS tube (M4), and an adjustable capacitor.

5. The millimeter wave injection locked tripler of claim 1, wherein, The frequency of the output signal is 3 times the frequency of the injected fundamental wave signal.

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