JP6344257B2 - Self-injection synchronous oscillator - Google Patents

Description

  The present invention relates to a self-injection synchronous oscillator applied to a microwave band or millimeter wave band transceiver.

  A voltage controlled oscillator (VCO) is one of the components that influence the quality of wireless communication. The phase noise characteristic of the VCO is an important characteristic because it determines the signal quality. Therefore, the VCO is required to have low phase noise. As a VCO having low phase noise, there is a self-injection synchronous oscillator. As a conventional self-injection synchronous oscillator, an oscillator shown in Non-Patent Document 1 is known.

  The self-injection synchronous oscillator is an oscillator configured to inject a part of the output signal of the VCO into the VCO itself via a delay line. In the self-injection synchronous oscillator, a feedback loop is formed by using the output signal of the VCO itself. Therefore, the oscillation frequency of the VCO is locked by the signal of the VCO itself, and the phase noise can be reduced.

  The phase noise in the self-injection locked oscillator is expressed by equation (1).

ここで、PN₀は自励発振時の位相雑音、ρは注入波電力（A_inj）と発振電力（A₀）の比（A_inj/A₀）、ω_3dBは位相雑音の３ｄＢ帯域幅、Ｔは遅延線路で生じる遅延時間である。

Here, PN ₀ is the phase noise at the time of self-oscillation, [rho is injected signal power (A _inj) and the oscillation power (A ₀₎ the ratio of _{(A inj / A 0),} ω 3dB is phase noise 3dB bandwidth, T is a delay time generated in the delay line.

  From equation (1), it can be seen that the larger the T, the lower the phase noise PN. Therefore, it is necessary to lengthen the delay line in order to reduce the phase noise.

Heng-Chia Chang, “Phase Noise in Self-Injection-Locked Oscillators—Theory and Experiment”, IEEE TRANSACTIONS ON MICROVE 3 TEA.

  In the conventional self-injection synchronous oscillator, the length of the delay line and the phase noise are in a trade-off relationship. Therefore, there is a problem that the phase noise cannot be reduced without lengthening the delay line. For this reason, it has been difficult to reduce the size of the self-injection synchronous oscillator while maintaining low phase noise.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a self-injection synchronous oscillator capable of reducing phase noise without lengthening a delay line.

A self-injection synchronous oscillator according to the present invention includes an oscillator that outputs a signal, a distributor that distributes a part of the output signal of the oscillator to a first injection wave and a second injection wave, and a frequency of the first injection wave. a first frequency converter for multiplying a frequency of the second injection wave, a second frequency converter first frequency converter multiplies the frequency different from the frequency of the first injection wave multiplication, A delay line for delaying the phase of the first injection wave distributed by the distributor, a first injection wave multiplied by the first frequency converter, and a second injection wave multiplied by the second frequency converter; And a mixer for outputting the difference frequency of the above to the oscillator.

  According to the present invention, a part of the output signal of the VCO is extracted as an injection wave, the injection wave is multiplied, the phase is delayed with respect to the multiplied injection wave, and then the frequency is again set to the frequency of the output signal of the VCO by the mixer. By injecting the converted and frequency converted signal into the VCO, the phase noise can be reduced without lengthening the delay line.

3 is a configuration diagram illustrating a configuration example of a self-injection synchronous oscillator according to Embodiment 1. FIG. FIG. 6 is a configuration diagram illustrating another configuration example of the self-injection synchronous oscillator according to the first embodiment. FIG. 6 is a configuration diagram showing a configuration example of a self-injection synchronous oscillator according to a second embodiment. FIG. 6 is a configuration diagram illustrating a configuration example of a self-injection synchronous oscillator according to a third embodiment. FIG. 10 is a configuration diagram illustrating a configuration example of a self-injection synchronous oscillator according to a fourth embodiment. It is a figure which shows the voltage frequency characteristic in a self injection synchronous oscillator. FIG. 10 is a configuration diagram illustrating another configuration example of the self-injection synchronous oscillator according to the fourth embodiment. FIG. 10 is a configuration diagram illustrating a configuration example of a self-injection synchronous oscillator according to a fifth embodiment.

Embodiment 1
FIG. 1 is a configuration diagram illustrating a configuration example of the self-injection synchronous oscillator according to the first embodiment.
This self-injection synchronous oscillator includes a VCO 1, a divider 2, an output terminal 3, a divider 4, a multiplier 5 (an example of a first frequency converter), a multiplier 6 (an example of a second frequency converter), a delay A line 7, a mixer 8 (mixer), and an amplifier 9 are provided.

The VCO 1 is a voltage-controlled oscillator that oscillates based on its own voltage frequency characteristic (VF characteristic) and outputs a signal, and includes an output terminal and an injection terminal for inputting an injection wave. VCO 1 oscillates at the fundamental oscillation frequency (f ₀ ). The output terminal of the VCO 1 is connected to the distributor 2. As the VCO 1, a differential oscillator such as a cross-coupled oscillator using a transistor or a differential Colpitts oscillator, a single-phase Colpitts oscillator, a negative resistance oscillator, or the like is used.

  The distributor 2 is a distributor that distributes the high-frequency signal output from the VCO 1 into an output wave and an injection wave. Here, the output wave is a signal output from an output terminal 3 to be described later, and the injection wave is a signal finally injected into the VCO 1. The distributor 2 is connected to the output terminal 3 and the distributor 4. As the distributor 2, a Wilkinson distributor, a directional coupler, or the like is used. Further, the distributor 2 may be a circuit having two transmission lines. A distributor having any configuration may be used as long as it can be distributed to the output wave and the injection wave.

  The output terminal 3 is a terminal from which the output wave distributed by the distributor 2 is output. The output signal of the VCO 1 is output from the output terminal 3 to the external circuit via the distributor 2.

  The distributor 4 is a distributor that distributes the injection wave distributed by the distributor 2 into an RF wave (an example of a first injection wave) and an LO wave (an example of a second injection wave). Here, among the signals distributed by the distributor 4, a signal input to an RF terminal of the mixer 8 described later is referred to as an RF wave, and a signal input to the LO terminal of the mixer 8 is referred to as an LO wave. The output terminal of the distributor 4 is connected to the multiplier 5 and the multiplier 6. As the distributor 4, a Wilkinson distributor, a directional coupler, or the like is used. Further, the distributor 4 may be a circuit having two transmission lines. Any distributor may be used as long as it can distribute signals.

  The multiplier 5 is a multiplier that multiplies the frequency of the RF wave distributed by the distributor 4 to n times. Here, n is a natural number. The output terminal of the multiplier 5 is connected to the delay line 7.

  The multiplier 6 is a multiplier that multiplies the frequency of the LO wave distributed by the distributor 4 by n-1. The output terminal of the multiplier 6 is connected to the mixer 8.

The delay line 7 is a circuit that delays the phase of the RF wave multiplied by the multiplier 5. The output terminal of the delay circuit 7 is connected to the mixer 8. For the delay line 7, a coaxial cable that allows a high-frequency band to pass, a waveguide, a planar microwave transmission line such as a microstrip line or CPW (CoPlanar Waveguide), an amplifier connected in multiple stages, an LC resonance circuit, and a filter circuit are used. . Amplifiers and filter circuits connected in multiple stages have an advantage that a large amount of phase shift can be obtained with a small area compared to a transmission line. The amount of phase shift of the delay line 7 is φ ₁ at the fundamental oscillation frequency.

  The mixer 8 mixes the RF wave delayed by the delay line 7 and the LO wave multiplied by the multiplier 6, and outputs the difference frequency between the RF wave and the LO wave as an injection wave to the VCO 1 via the amplifier 9. Mixer to do. The mixer 8 includes an RF terminal, an LO terminal, and an IF terminal. The RF terminal of the mixer 8 is connected to the delay line 7, the LO terminal is connected to the multiplier 6, and the IF terminal is connected to the amplifier 9. The mixer 8 may be a double balance type mixer such as a Gilbert cell mixer or a drain mixer, a double balance type mixer using a diode, a single end type mixer, a single balance type mixer, or the like.

  The amplifier 9 is an amplifier that amplifies the injection wave output from the mixer 8 and outputs the amplified wave to the VCO 1. The amplifier 9 also operates as a buffer amplifier and prevents a signal from flowing backward from the VCO 1 to the mixer 8. Further, the amplifier 9 controls whether or not to inject an injection wave into the VCO 1 by switching the ON / OFF thereof.

Next, the operation of the self-injection synchronous oscillator according to the first embodiment will be described.
The VCO 1 oscillates at the fundamental oscillation frequency and outputs a signal to the distributor 2. Assume that the output signal of VCO 1 is sin (ωt + φ ₀ ). Here, ω is an angular frequency of the fundamental oscillation frequency f ₀ of VCO 1, and ω = 2πf ₀ . φ ₀ is the initial phase at ω.

  The distributor 2 splits the output signal of the VCO 1 into two and distributes it to the output wave and the injection wave. The output wave is output to the output terminal 3 and output from the output terminal 3 to an external circuit. The injection wave is output to the distributor 4.

Distributor 4, the injection wave 2 branches, distributed to the R F wave and LO wave. The RF wave is output to the multiplier 5, and the LO wave is output to the multiplier 6.

The multiplier 5 multiplies the RF wave by n times. The RF wave multiplied by n times is output to the delay line 7. The signal output to the delay line 7 is sin n (ωt + φ ₀ ).

The delay line 7 delays the phase of the multiplied RF wave and outputs the delayed signal to the RF terminal of the mixer 8. Delay line 7, because it provides a phase shift of phi ₁ against omega, against nω give phase shift of nφ _1. Therefore, the signal output from the delay line 7 to the mixer 8 is sin n (ωt + φ ₀ + φ ₁ ). In this way, by providing the delay line 7 for the multiplied RF wave and delaying the phase, an n times delayed phase is obtained compared to the case where the phase is delayed without multiplying the RF wave. be able to.

The multiplier 6 multiplies the LO wave by n−1 times and outputs it to the LO terminal of the mixer 8. The signal output from the multiplier 6 to the mixer 8 is sin (n−1) (ωt + φ ₀ + φ ₁ ).

The mixer 8 mixes the RF wave output from the delay line 7 and the LO wave output from the multiplier 6 and outputs the difference frequency to the amplifier 9. The difference frequency is sin (ωt + φ ₀ + nφ ₁ ).

The amplifier 9 amplifies the difference frequency output from the mixer 8 and injects it into the VCO 1. The signal injected into the VCO ₁ is sin (ωt + φ ₀ + nφ ₁ ).

An injection wave is injected into the VCO 1 via the amplifier 9. Since the injected signal is sin (ωt + φ ₀ + nφ ₁ ), the injection signal of the conventional self-injection synchronous oscillator is sin (ωt + φ ₀ + φ ₁ ). In the synchronous oscillator, a delay phase that is n times that of the conventional case can be obtained. Since the delay time T and the delay phase φ are related by ωT = φ, the fact that an n-fold delay phase is obtained means that an n-fold delay time is obtained. For this reason, in this self-injection synchronous oscillator, the delay time can be increased without lengthening the delay line.

  As shown in Equation (1), the phase noise of the oscillator decreases as the delay time increases. Therefore, the present self-injection synchronous oscillator can reduce the phase noise as compared with the conventional self-injection synchronous oscillator. Since the self-injected synchronous oscillator can reduce the phase noise without lengthening the delay line, it can be configured smaller than the conventional one. For example, if a conventional self-injection synchronous oscillator requires a delay line of 100 mm, the present self-injection synchronous oscillator has a phase noise characteristic equivalent to that of a 33-mm delay line when n = 3. can get.

  As described above, according to the first embodiment, a part of the output signal of VCO 1 is extracted as an injection wave, the injection wave is multiplied, the phase is delayed with respect to the multiplied injection wave, and the mixer outputs the VCO 1 again. The frequency is converted to the frequency of the signal, and the frequency-converted signal is injected into the VCO 1. Thereby, even if the delay line 7 is not lengthened, the delay phase can be increased and the phase noise can be reduced.

Here, an example in which the delay line 7 is provided between the multiplier 5 and the mixer 8 has been described, but the delay line 7 may be provided anywhere between the distributor 4 and the mixer 8.
FIG. 2 is a configuration diagram showing another configuration example of the self-injection synchronous oscillator according to the first embodiment.
FIG. 2A shows an example in which a delay line 7 is provided between the multiplier 6 and the mixer 8. Also in the configuration of FIG. 2A, the injection wave is multiplied, the phase of the multiplied injection wave is delayed, and the delayed injection wave is converted into the frequency of the output signal of the VCO 1 by the mixer 8, and thus described above. Has the effect.

FIG. 2B shows an example in which a delay line 7 is provided between the distributor 4 and the multiplier 5.
In FIG. 2B, after the phase of the injection wave is delayed, the injection wave is multiplied by the multiplier 5, but when the signal is multiplied by the multiplier 5, the phase of the signal is also multiplied. The same delay phase as in the case can be obtained. In FIG. 2B, if the signal output from the delay line 7 is sin (ωt + φ ₀ + φ ₁ ), the signal output from the multiplier 5 is sin n (ωt + φ ₀ + φ ₁ ). This signal is input to the mixer 8. Since the phase of the signal input to the mixer 8 shown in FIG. 2 and the phase of the signal input to the mixer 8 shown in FIG. 1 coincide with each other, the configuration shown in FIG.

  In FIG. 2B, the delay line 7 gives a delay phase to the injection wave before the multiplier 5 increases the frequency of the injection wave. Therefore, the frequency of the signal passing through the delay line 7 can be lowered, and the loss due to the delay line 7 can be reduced.

  FIG. 2C shows a configuration example when a multiplier 10 that multiplies an injection wave by n-2 times is used instead of the multiplier 6 that multiplies the injection wave by n-1. Even in this configuration, since the delay line 7 is provided after multiplying the injected wave, the delay phase can be increased.

In the configuration of FIG. 2C, the signal output from the mixer 8 is sin (2ωt + 2φ ₀ + nφ ₁ ), and twice the harmonics are injected into the VCO 1 with respect to the signal output from the VCO ₁ . become. Even if the signal injected into the VCO 1 is different from the frequency of the output signal of the VCO 1, the phase noise can be reduced for the following reason.

Consider the operation within VCO1. The VCO 1 includes a transistor that outputs a signal and a feedback circuit that feeds back the signal to the transistor. The VCO 1 oscillates by feeding back a signal to the transistor and outputs the signal. Therefore, a signal having the same frequency as the output signal of VCO 1 is input to the transistor in VCO 1. Further, since an injection signal is injected into the VCO 1 from the mixer 8, the injection signal is also input to a transistor in the VCO 1. Since the transistor operates non-linearly in the VCO 1, when two signals are input, the transistor generates a mixed wave. The mixed wave is expressed as mixed wave = L · S ₁ + M · S ₂ (S ₁ is the frequency of the output signal, S ₂ is the frequency of the injection signal, and L and M are integers). If the frequency of the mixed wave is equal to the frequency of the output signal of VCO1, the oscillation of VCO1 is locked through the mixed wave, so that the phase noise of VCO1 is reduced.

The condition that the mixed wave is equal to the output signal of the VCO ₁ is expressed by S ₁ = L · S ₁ + M · S _2. When this equation is satisfied, the phase noise of the VCO 1 is reduced. The left side represents the output signal of VCO1, and the right side represents the mixed wave. Here, satisfying S ₁ = L · S ₁ + M · S ₂ means that L and M satisfying this equation exist.

FIG. 2D shows a configuration example in which a multiplier 11 that divides the injection wave by 2 is used instead of the multiplier 6 that multiplies the injection wave by n-1. Even in this configuration, since the delay line 7 is provided after multiplying the injected wave, the delay phase can be increased.
In the configuration of FIG. 2D, the signal output from the mixer 8 is sin ((2n−1) / 2) (ωt + φ ₀ ) + nφ ₁ ). Considering the above formula S ₁ = L · S ₁ + M · S ₂ , ω = L · ω + M · (2n−1) · ω / 2. When n = 1, when L = 0 and M = 2 Satisfies the above formula. In the case of n = 2, the above formula is satisfied when L = 4 and M = −2. Therefore, phase noise can be reduced even with the configuration of FIG.

Embodiment 2. FIG.
In the first embodiment, a configuration using two multipliers has been described. In the second embodiment, a self-injection synchronous oscillator having a configuration in which one multiplier is reduced will be described.

FIG. 3 is a configuration diagram illustrating a configuration example of the self-injection synchronous oscillator according to the second embodiment.
In FIG. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted. Compared to the configuration of the first embodiment, the self-injection synchronous oscillator of the second embodiment eliminates the multiplier 6 and, instead of VCO 1, a VCO 12 that outputs a fundamental wave and an n−1 harmonic, and an amplifier 14. It has. The VCO 12 outputs the n−1 harmonic wave to the mixer 8 via the amplifier 14, and outputs a part of the fundamental wave to the mixer 8 via the distributor 2, the multiplier 5 and the delay line 7.

The VCO 12 is an oscillator that outputs a fundamental wave and an n-1 harmonic, and includes a fundamental wave output terminal that outputs a fundamental wave, a harmonic output terminal that outputs an n-1 harmonic, and an injection terminal that inputs an injection wave. Prepare. For example, the VCO 12 is an oscillator that outputs a fundamental wave and a harmonic as an output signal. The VCO 12 is provided with a filter through which a harmonic passes and a filter through which the fundamental passes through the output signal. And harmonics are separated and output. The VCO 12 oscillates at the fundamental oscillation frequency (f ₀ ). The fundamental output terminal of the VCO 12 is connected to the distributor 2, and the harmonic output terminal of the VCO 12 is connected to the amplifier 14. As the VCO 12, a differential oscillator such as a cross-coupled oscillator using a transistor or a differential Colpitts oscillator, a single-phase Colpitts oscillator, a negative resistance oscillator, or the like is used.

  The amplifier 14 is an amplifier that amplifies the n-1 harmonic output from the VCO 12. The output terminal of the amplifier 14 is connected to the LO terminal of the mixer 8. Generally, since the harmonic power is smaller than the fundamental wave, the harmonic power is amplified by the amplifier 14.

Next, the operation of the self-injection synchronous oscillator according to the second embodiment will be described.
The VCO 12 oscillates at the fundamental oscillation frequency and outputs a fundamental wave signal to the distributor 2. Further, the VCO 12 outputs a harmonic signal to the amplifier 14. The fundamental wave signal of the VCO 12 is sin (ωt + φ ₀ ), and the harmonic output signal is sin (n−1) (ωt + φ ₀ ).

  The amplifier 14 amplifies the harmonic signal output from the VCO 12 and outputs the amplified harmonic signal to the LO terminal of the mixer 8 as an LO wave.

  The distributor 2 distributes the fundamental wave signal of the VCO 12 into an output wave and an RF wave. The output wave is output to the output terminal 3 and output from the output terminal 3 to an external circuit. The RF wave is output to the multiplier 5.

The multiplier 5 multiplies the RF wave output from the distributor 2 by n times. The RF wave multiplied by n times is output to the delay line 7. The signal output to the delay line 7 is sin n (ωt + φ ₀ ).

The delay line 7 delays the phase of the multiplied RF wave and outputs the delayed signal to the RF terminal of the mixer 8. Delay line 7, because it provides a phase shift of phi ₁ against omega, against nω give phase shift of nφ _1. Therefore, the signal output from the delay line 7 to the mixer 8 is sin n (ωt + φ ₀ + φ ₁ ). In this way, by providing the delay line 7 for the multiplied RF wave and delaying the phase, an n times delayed phase is obtained compared to the case where the phase is delayed without multiplying the RF wave. be able to.

The mixer 8 mixes the RF wave output from the delay line 7 and the LO wave output from the amplifier 14, and outputs the difference frequency to the amplifier 9. The difference frequency is sin (ωt + φ ₀ + nφ ₁ ).

The amplifier 9 amplifies the difference frequency output from the mixer 8 and injects it into the VCO 12. The signal injected into the VCO 12 is sin (ωt + φ ₀ + nφ ₁ ).

An injection wave is injected into the VCO 12 via the amplifier 9. Since the injected signal is sin (ωt + φ ₀ + nφ ₁ ), the injection signal of the conventional self-injection synchronous oscillator is sin (ωt + φ ₀ + φ ₁ ). In the synchronous oscillator, a delay phase that is n times that of the conventional case can be obtained. Since the delay time T and the delay phase φ are related by ωT = φ, the fact that an n-fold delay phase is obtained means that an n-fold delay time is obtained. In this self-injection synchronous oscillator, the delay time can be increased without lengthening the delay line.

  As shown in Equation (1), the phase noise of the oscillator decreases as the delay time increases. Therefore, the present self-injection synchronous oscillator can reduce the phase noise as compared with the conventional self-injection synchronous oscillator. Since the self-injected synchronous oscillator can reduce the phase noise without lengthening the delay line, it can be configured smaller than the conventional one. For example, if a conventional self-injection synchronous oscillator requires a delay line of 100 mm, the present self-injection synchronous oscillator has a phase noise characteristic equivalent to that of a 33-mm delay line when n = 3. can get.

  Even the self-injection synchronous oscillator according to the second embodiment configured as described above has the same effects as those of the first embodiment. In addition, since the self-injection synchronous oscillator of the second embodiment uses the harmonic of the VCO 12 as the LO wave of the mixer 8, the multiplier 6 required in the first embodiment can be reduced, the circuit can be simplified, Miniaturization can be achieved.

Embodiment 3 FIG.
In the second embodiment, a configuration using one multiplier is shown. In the third embodiment, a self-injection synchronous oscillator having a configuration without using a multiplier will be described.

FIG. 4 is a configuration diagram showing a configuration example of the self-injection synchronous oscillator according to the third embodiment.
4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted. Compared to the configuration of the first embodiment, the self-injection synchronous oscillator of the third embodiment includes the VCO 13 that eliminates the multiplier 5 and the multiplier 6 and outputs a fundamental wave and a second harmonic instead of the VCO 1. Yes. The VCO 13 outputs the second harmonic to the mixer 8 via the delay line 7 and outputs a part of the fundamental wave to the mixer 8 via the distributor 2.

Next, the operation of the self-injection synchronous oscillator according to the third embodiment will be described.
The VCO 13 oscillates at the fundamental oscillation frequency and outputs a fundamental wave signal to the distributor 2. The VCO 13 outputs the second harmonic signal to the delay line 7 as an RF wave. The fundamental wave signal of the VCO 13 is sin (ωt + φ ₀ ), and the harmonic output signal is sin 2 (ωt + φ ₀ ).

  The distributor 2 distributes the fundamental wave signal of the VCO 12 into an output wave and an LO wave. The output wave is output to the output terminal 3 and output from the output terminal 3 to an external circuit. The LO wave is output to the LO terminal of the mixer 8.

The delay line 7 delays the phase of the harmonic output by the VCO 13 as an RF wave, and outputs the delayed RF wave to the RF terminal of the mixer 8. Delay line 7, because it provides a phase shift of phi ₁ against omega, against 2ω gives the amount of phase shift of 2 [phi _1. Therefore, the signal output from the delay line 7 to the mixer 8 is sin 2 (ωt + φ ₀ + φ ₁ ). In this way, by providing the delay line 7 for the harmonic and delaying the phase, it is possible to obtain a delay phase that is twice that of the case where the phase is delayed with respect to the fundamental wave.

The mixer 8 mixes the RF wave output from the delay line 7 and the LO wave output from the distributor 2, and outputs the difference frequency to the amplifier 9. The difference frequency is sin (ωt + φ ₀ + 2φ ₁ ).

The amplifier 9 amplifies the difference frequency output from the mixer 8 and injects it into the VCO 13. The signal injected into the VCO 13 is sin (ωt + φ ₀ + 2φ ₁ ).

An injection wave is injected into the VCO 13 via the amplifier 9. The injected signal is sin (ωt + φ ₀ + 2φ ₁ ), whereas the injection signal of the conventional self-injection synchronous oscillator is sin (ωt + φ ₀ + φ ₁ ). In the synchronous oscillator, the delay phase can be doubled compared to the conventional case. Since the delay time T and the delay phase φ are related by ωT = φ, the fact that a double delay phase is obtained means that a double delay time is obtained. In this self-injection synchronous oscillator, the delay time can be increased without lengthening the delay line.

  As shown in Equation (1), the phase noise of the oscillator decreases as the delay time increases. Therefore, the present self-injection synchronous oscillator can reduce the phase noise as compared with the conventional self-injection synchronous oscillator. Since the self-injected synchronous oscillator can reduce the phase noise without lengthening the delay line, it can be configured smaller than the conventional one. For example, if a conventional self-injection synchronous oscillator requires a delay line of 100 mm, this self-injection synchronous oscillator can obtain an equivalent phase noise characteristic using a delay line of 50 mm.

  Even the self-injection synchronous oscillator of the third embodiment configured as described above has the same effect as that of the first embodiment. In addition, the self-injection synchronous oscillator according to the third embodiment uses a part of the fundamental wave output from the VCO 13 as the LO wave of the mixer 8 and uses the harmonic wave output from the VCO 13 as the RF wave. Therefore, the multiplier 5 and the multiplier 6 required in the first embodiment can be reduced, and the circuit can be simplified and downsized.

Embodiment 4 FIG.
In the fourth embodiment, a self-injection synchronous oscillator capable of increasing the range in which the oscillation frequency continuously changes as compared with the self-injection synchronous oscillator of the first embodiment will be described.

FIG. 5 is a configuration diagram illustrating a configuration example of the self-injection synchronous oscillator according to the fourth embodiment.
In FIG. 5, the same reference numerals as those in FIG. Compared to the configuration of the first embodiment, a difference is that a phase shifter 15 is provided between the delay line 7 and the multiplier 5.

  The phase shifter 15 is a phase shifter that applies a phase shift amount to the RF wave output from the distributor 4 and matches the phase of the signal output from the VCO 1 and the phase of the signal injected into the VCO 1. The amount of phase shift is controlled by voltage or current. An input terminal of the phase shifter 15 is connected to the multiplier 5, and an output terminal of the phase shifter 15 is connected to the delay line 7.

Next, the operation of the self-injection synchronous oscillator according to the fourth embodiment will be described.
Since the operations of the VCO 1, the divider 2, the output terminal 3, the divider 4, the multiplier 5 and the multiplier 6 are the same as those in the first embodiment, description thereof is omitted.

The phase shifter 15 gives a phase shift amount to the RF wave output from the multiplier 5. The amount of phase shift is Δφ with respect to ω. Then, since the frequency of the RF wave output from the multiplier 5 is nω, the phase shifter 15 gives the phase shift amount of nΔφ to the RF wave. Therefore, the output signal of the phase shifter 15 is sin n (ωt + φ ₀ + Δφ).

The delay line 7 delays the phase of the RF wave output from the phase shifter 15 and outputs the delayed signal to the RF terminal of the mixer 8. Delay line 7, because it provides a phase shift of phi ₁ against omega, against nω give phase shift of nφ _1. Therefore, the signal output from the delay line 7 to the mixer 8 is sin n (ωt + φ ₀ + φ ₁ + Δφ). In this way, by providing the delay line 7 for the multiplied RF wave and delaying the phase, an n times delayed phase is obtained compared to the case where the phase is delayed without multiplying the RF wave. be able to.

The mixer 8 mixes the RF wave output from the delay line 7 and the LO wave output from the multiplier 6 and outputs the difference frequency to the amplifier 9. The difference frequency is sin (ωt + φ ₀ + n (φ ₁ + Δφ)).

The amplifier 9 amplifies the difference frequency output from the mixer 8 and injects it into the VCO 1. The signal injected into the VCO 1 is sin (ωt + φ ₀ + n (φ ₁ + Δφ)).

An injection wave is injected into the VCO 1 via the amplifier 9. Since an injection wave having an n-fold delay phase is injected into the VCO 1 as compared with the prior art, the phase noise of the VCO 1 is improved as described in the first embodiment.
Since the signal injected into the VCO 1 is sin (ωt + φ ₀ + n (φ ₁ + Δφ)) and the output signal of the VCO ₁ is sin (ωt + φ ₀ ), generally the phase of the injected signal And the phase of the output signal is different.

Here, the phase shifter 15 controls Δφ so that the phase of the output signal of the VCO 1 matches the phase of the signal injected into the VCO 1. That is, the phase shifter 15 controls Δφ so as to satisfy the condition of n (φ ₁ + Δφ) = 2kπ (k is an integer). As a result, the output signal of the VCO 1 and the signal injected into the VCO 1 have the same frequency and phase.

  When the phase of the injected signal and the output signal do not match, as shown below, the variation range of the oscillation frequency with respect to the control voltage of the self-injection synchronous oscillator becomes small.

FIG. 6 is a diagram showing voltage frequency characteristics in the self-injection synchronous oscillator. The solid line shows the voltage frequency characteristic when the phase of the injection signal and the output signal match. The dotted line indicates the voltage frequency characteristic when the phase of the injection signal and the output signal do not match.
When the phase of the injection signal and the output signal do not match, it can be seen that the frequency becomes discontinuous when the control voltage is changed. The self-injection synchronous oscillator basically oscillates so that the phases of the injection signal and the output signal match. Therefore, when there is no phase, the self-injection synchronous oscillator operates so as to change the oscillation frequency and match the phases of the injection signal and the output signal. When the phase difference between the injection signal and the output signal becomes large, the oscillation frequency needs to be changed greatly, so that the oscillation frequency changes discontinuously. For this reason, the range in which the oscillation frequency continuously changes with respect to the control voltage is narrowed.

  On the other hand, when the phase of the injection signal matches the phase of the output signal, the self-injection synchronous oscillator does not need to change the oscillation frequency, so the oscillation frequency does not change discontinuously, As shown in FIG. 6, the characteristic that the oscillation frequency continuously changes with respect to the control voltage is obtained.

  Even the self-injection synchronous oscillator of the fourth embodiment configured as described above has the same effects as those of the first embodiment. In addition, since the self-injection synchronous oscillator according to the fourth embodiment uses the phase shifter 15 to match the phase of the output signal of the VCO 1 and the phase of the signal injected into the VCO 1, the oscillation frequency is continuously increased. The range to change can be enlarged. Therefore, the self-injection locked oscillator according to the fourth embodiment can output a broadband signal.

  Here, an example in which the phase shifter 15 is provided between the multiplier 5 and the delay line 7 is shown. However, if the phase shifter 15 is in a loop for an injection wave from the distributor 2 to the VCO 1 via the amplifier 9. The phase shifter 15 may be provided anywhere. This is because if there is a phase shifter 15 in the loop of the injection wave, the phase of the injection wave can be changed.

FIG. 7 is a configuration diagram showing another configuration example of the self-injection synchronous oscillator according to the fourth embodiment.
FIG. 7A shows an example in which a phase shifter 15 is provided between the distributor 4 and the multiplier 5. By providing the phase shifter 15 in front of the multiplier 5, the phase shifter 15 operates at a low frequency before being multiplied, so that the loss of the phase shifter 15 with respect to the injected wave can be reduced.

  FIG. 7B is an example in which a phase shifter 15 is provided between the distributor 2 and the distributor 4. Even if the phase shifter 15 is provided at this position, the phase of the injection wave can be changed, so that the phase of the injection wave and the phase of the output signal can be matched. Further, as in the case of FIG. 7A, the phase shifter 15 operates at a low frequency before being multiplied, so that the loss of the phase shifter 15 with respect to the injected wave can be reduced.

  FIG. 7B is an example in which a phase shifter 15 is provided between the distributor 2 and the distributor 4. FIG. 7C shows an example in which a phase shifter 15 is provided between the mixer 8 and the amplifier 9. Even if the phase shifter 15 is provided at these positions, the phase of the injection wave can be changed, so that the phase of the injection wave and the phase of the output signal can be matched.

Embodiment 5. FIG.
In the fifth embodiment, a configuration of a self-injection synchronous oscillator capable of reducing one multiplier without using an oscillator that outputs harmonics will be described.

FIG. 8 is a configuration diagram showing a configuration example of the self-injection synchronous oscillator according to the fifth embodiment.
In FIG. 8, the same reference numerals as those in FIG. The difference from the configuration of the first embodiment is that the multiplier 6 is omitted and a harmonic mixer 81 is provided instead of the mixer 8.

  The harmonic mixer 81 is a harmonic mixer that mixes LO harmonics and RF waves. The harmonic mixer 81 includes an RF terminal, an LO terminal, and an IF terminal. The RF terminal of the harmonic mixer 81 is connected to the delay line 7, the LO terminal is connected to the distributor 4, and the IF terminal is connected to the amplifier 9. The harmonic mixer 81 mixes the RF wave delayed by the extension line 7 and the harmonics of the LO wave output from the distributor 4, and injects the difference frequency between the RF wave and the LO wave into the VCO 1 via the amplifier 9. Output as a wave. For example, the harmonic mixer 81 is a common mixer or an anti-parallel diode pair mixer.

Next, the operation of the self-injection synchronous oscillator according to the fifth embodiment will be described.
Since the operations of the VCO 1, the divider 2, the output terminal 3, the divider 4 and the multiplier 5 are the same as those in the first embodiment, description thereof is omitted.

The harmonic mixer 81 receives an RF wave from the delay line 7 and an LO wave from the distributor 4. The RF wave is sin n (ωt + φ ₀ + φ ₁ ), and the LO wave is sin (ωt + φ ₀ ). The harmonic mixer 81 uses the n-1 harmonic of the LO wave, mixes the n-1 harmonic of the LO wave and the RF wave, and outputs the difference frequency to the amplifier 9. Here, n represents the multiplication number of the multiplier 5. Since the n-1 harmonic of the LO wave is sin (n-1) (ωt + φ ₀ ), the difference frequency between the n-1 harmonic of the LO wave and the RF wave is sin (ωt + φ ₀ + nφ ₁ ).

  Since the operations of the amplifier 9 and the VCO 1 are the same as those in the first embodiment, description thereof is omitted.

Even in the self-injection synchronous oscillator of the fifth embodiment configured as described above, the signal injected into the VCO ₁ is sin (ωt + φ ₀ + nφ ₁ ), and thus the same effect as that of the first embodiment is obtained. Play. In addition, since the self-injection locked oscillator according to the fifth embodiment uses the harmonic mixer 81 to mix the harmonics of the LO wave and the RF wave, the multiplier 6 required in the first embodiment can be reduced. The circuit can be simplified and downsized.

In the above description, the harmonic mixer 81 uses the n-1 harmonic of the LO wave. However, the harmonic mixer 81 may use the n + 1 harmonic of the LO wave. In this case, the difference frequency between the n + 1 harmonic of the LO wave and the RF wave is −sin (ωt + φ ₀ −nφ ₁ ), and a delay phase that is −n times that of ω is obtained. The delay phase is meaningful in absolute value, the same effect as Enufai ₁ is obtained even -nφ _1. Therefore, using n + 1 harmonics has the same effect as using n-1 harmonics.

  Furthermore, when the harmonic mixer 81 uses n + 1 harmonics and n = 1, that is, when the harmonic mixer 81 performs mixing using the second harmonic of the LO wave, the multiplication factor of the multiplier 5 is used. Becomes 1, so the multiplier 5 can be reduced. In this case, since the multiplier 5 and the multiplier 6 can be reduced, the circuit can be further simplified and downsized.

1 12 13 VCO, 2 4 distributor, 3 output terminal, 5 6 10 multiplier, 7 delay line, 8 mixer, 9 14 amplifier, 11 frequency divider, 15 phase shifter, 81 harmonic mixer.

Claims (6)

An oscillator that outputs a signal;
A distributor for distributing a part of an output signal of the oscillator to a first injection wave and a second injection wave;
A first frequency converter for multiplying the frequency of the first injection wave;
A second frequency converter that multiplies the frequency of the second injection wave to a frequency different from the frequency of the first injection wave multiplied by the first frequency converter;
A delay line for delaying the phase of the first injection wave distributed by the distributor;
A mixer that outputs a difference frequency between the first injection wave multiplied by the first frequency converter and the second injection wave multiplied by the second frequency converter to the oscillator; Self-injection synchronous oscillator.   The self-injection synchronous oscillator according to claim 1, further comprising an amplifier that amplifies the difference frequency output from the mixer.   3. The self-injection synchronous oscillator according to claim 1, further comprising a phase shifter configured to match a phase of the output signal of the oscillator with a phase of the difference frequency output to the oscillator.   The relationship between the frequency S1 of the output signal of the oscillator and the frequency S2 of the difference frequency output from the mixer satisfies S1 = L · S1 + M · S2 (L and M are integers). The self-injection synchronous oscillator according to any one of the above. An oscillator that outputs signals including harmonics and fundamental waves;
A frequency converter that multiplies a frequency of a part of the fundamental wave output from the oscillator to a frequency different from the harmonic;
A delay line for delaying the phase of a part of the fundamental wave output from the oscillator;
A self-injection synchronous oscillator comprising a mixer that outputs a difference frequency between a part of the fundamental wave output from the oscillator and the harmonic output from the oscillator to the oscillator. An oscillator that outputs signals including harmonics and fundamental waves;
A delay line that delays the phase of the harmonics output by the oscillator;
A self-injection synchronous oscillator comprising a mixer that outputs a difference frequency between a part of the fundamental wave output from the oscillator and the harmonic output from the oscillator to the oscillator.

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