Injection-locked oscillator circuit

Abstract

To provide an injection synchronous oscillation circuit that can apply a high-frequency current pulse to differential pairs of a differential output oscillator in a well-balanced manner.SOLUTION: An injection synchronous oscillation circuit 1 includes: a differential output oscillator 10 having a pair of LC oscillators, the differential output oscillator outputting an oscillation output signal with a predetermined oscillation frequency; and an injection circuit 20 for injecting a signal according to a referential signal into the differential output oscillator 10. The injection circuit 20 includes: a pulse generation unit 30 for generating a current pulse according to a reference signal; and an injection unit 40 having an injection inductor 41 for generating a dielectric current in a pair of inductors 13, 14 of the pair of LC oscillators by input of the current pulse generated by the pulse generation unit 30 and a variable capacitor 42 serially connected to the injection inductor 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an injection-locked oscillator circuit that performs injection locking on an oscillator. [Background technology]

[0002] Injection locking is a conventional technique known in which an oscillator is synchronized to an applied signal by applying a perturbation very close to the oscillation frequency, and in the case of integrated circuits, research by Adler et al. was conducted in the 1970s (see Non-Patent Document 1). For oscillator circuits in integrated circuits, a method of applying a current to a resonator using transistor switching is also known (see Non-Patent Documents 2 to 4). The method in Non-Patent Document 2 applies an injection current using a switching transistor between the differential pair of the oscillator circuit. The method in Non-Patent Document 3 applies an injection current using a transistor to each of the differential pair of the oscillator. The method in Non-Patent Document 4 injects a current into one of the differential pair and extracts the current from the other. All of these methods apply a current directly to the oscillator. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] R. Adler, "A Study of Locking Phenomena in Oscillators," Proc. IEEE, vol.61, pp. 1380-1385, Oct. 1973 [Non-patent document 2] BM Helal, et al., "A Low Jitter Programmable Clock Multiplier Based on a Pulse Injection-Locked Oscillator With a Highly-Digital Tuning Loop," IEEE JSSC, vol. 44, pp. 1391-1400, May 2009 [Non-patent document 3] J. Lee, and H. Wang, "Study of Subharmonically Injection-Locked PLLs," IEEE JSSC, vol. 44, pp. 1539-1553, May 2009 [Non-patent document 4] T. Yoshimura, "Study of Injection Pulling of Oscillators in Phase-Locked Loops," IEEE TVLSI Systems, vol. 44, pp.321-332, Feb. 2021 Summary of the Invention [Problem to be solved by the invention]

[0004] In the injection locking method using a transistor to apply a current between a differential pair of an oscillator, as in Non-Patent Document 2, it is necessary to apply a pulse signal with a sufficiently large voltage amplitude (a pulse voltage equal to or greater than the oscillation amplitude) to the transistor according to the amplitude of the oscillator. However, when the oscillator operates at a high frequency, it is difficult to generate such a signal. This is because, in general, the higher the frequency, the smaller the amplitude.

[0005] Furthermore, in the method of applying a current to each of the differential pair using a transistor as in the above-mentioned Non-Patent Document 3, although there is no limit to the amplitude of the injected signal, there is a problem in that an asymmetric current fluctuation is applied to the differential pair of the oscillator, which may cause unnecessary noise due to the common mode to be applied to the oscillator.

[0006] Furthermore, the method of applying a current by injecting a current into one of a differential pair and extracting a current from the other, as in Non-Patent Document 4, has the problem that it is technically difficult to apply a current generated by a high-frequency pulse to an oscillator in a balanced manner. Achieving such a balanced application requires a large circuit scale, and if a balanced application cannot be achieved, there is the problem of common-mode noise occurring, as in Non-Patent Document 3.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide an injection-locked oscillator circuit that can apply high-frequency current pulses in a balanced manner to each of the differential pairs of a differential output oscillator. [Means for solving the problem]

[0008] To achieve the above object, an injection-locked oscillator circuit according to one aspect of the present invention comprises a differential output oscillator having a pair of LC oscillators and outputting an oscillation output signal of a predetermined oscillation frequency, and an injection circuit for injecting a signal corresponding to a reference signal into the differential output oscillator, the injection circuit having a pulse generating unit that generates a current pulse corresponding to the reference signal, and an injection unit having an injection inductor that generates an induced current in a pair of inductors in the pair of LC oscillators when the current pulse generated by the pulse generating unit is input. An example of an injection-locked oscillator circuit according to this aspect may be, for example, that shown in FIG.

[0009] This configuration utilizes electromagnetic coupling to apply an induced current to the oscillator's resonant section through mutual induction, thereby achieving injection locking, enabling efficient application of current pulses to the oscillator. It also enables balanced application of current pulses to each of the pair of LC oscillators in the differential output oscillator, reducing common-mode noise. Furthermore, since the reference signal voltage only needs to be capable of generating a current pulse, there is no need to use a reference signal with a large voltage corresponding to the oscillator's output amplitude, as in conventional examples. For example, it can easily accommodate high-frequency oscillation output signals. Furthermore, because the induced current is determined by the coil shape and arrangement, stable performance can be maintained regardless of circuit operating conditions such as temperature.

[0010] In the injection-locked oscillator circuit according to an aspect of the present invention, the inductance of the injection inductor may be greater than the inductance of each of the pair of inductors. This configuration makes it possible to generate an induced current in the oscillator inductor that is greater than that generated by the injection inductor. In the injection locking method, which reduces phase noise by applying a pulsed current to the oscillator, it is known that the greater the applied current, the greater the phase noise suppression effect. Therefore, by generating a larger induced current in this way, the phase noise reduction effect can be improved.

[0011] In an injection-locked oscillator circuit according to an aspect of the present invention, the injection section may further include a capacitor connected in series with the injection inductor, and the resonant frequency of the resonator formed by the injection inductor and the capacitor may be M times the oscillation frequency (M is an integer equal to or greater than 1). An example of an injection-locked oscillator circuit according to this aspect may be, for example, one shown in FIGS. 1 to 4. With this configuration, multiple current pulses can be applied to each of a pair of LC oscillators in response to the input of a single current pulse to the injection unit, thereby achieving efficient injection locking.

[0012] In an injection-locked oscillator circuit according to an aspect of the present invention, the differential output oscillator outputs an oscillation output signal having an oscillation frequency according to a control voltage, and the capacitance of the capacitor may be changed so that the resonant frequency is M times the oscillation frequency of the differential output oscillator. An example of an injection-locked oscillator circuit according to this aspect may be, for example, that shown in FIG. With this configuration, the oscillation frequency of the differential output oscillator can be changed, and the frequency of the current pulses injected into the differential output oscillator can be made to match the oscillation frequency of the differential output oscillator. [Effects of the Invention]

[0013] According to an injection-locked oscillator circuit of one aspect of the present invention, injection locking is performed by applying an induced current to a resonant part of an oscillator using electromagnetic coupling, so that, for example, a high-frequency current pulse can be efficiently applied to the oscillator. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a circuit diagram showing a configuration of an injection-locked oscillator circuit according to an embodiment of the present invention; [Figure 2] FIG. 10 is a circuit diagram showing another configuration of the injection-locked oscillator circuit according to the embodiment; [Figure 3] FIG. 10 is a circuit diagram showing another configuration of the injection-locked oscillator circuit according to the embodiment; [Figure 4] FIG. 10 is a circuit diagram showing another configuration of the injection-locked oscillator circuit according to the embodiment; [Figure 5] FIG. 10 is a circuit diagram showing another configuration of the injection-locked oscillator circuit according to the embodiment; [Figure 6] Graph showing simulation results in the same embodiment DETAILED DESCRIPTION OF THE INVENTION

[0015] An injection-locked oscillator circuit according to the present invention will be described below using embodiments. In the following embodiments, components with the same reference numerals are the same or equivalent, and repeated description may be omitted. The injection-locked oscillator circuit according to this embodiment performs injection locking by applying induced currents to a pair of LC oscillators of a differential output oscillator using electromagnetic coupling.

[0016] 1 is a circuit diagram showing the configuration of an injection-locked oscillator circuit 1 according to this embodiment. The injection-locked oscillator circuit 1 according to this embodiment includes a differential output oscillator 10 that outputs an oscillation output signal of a predetermined oscillation frequency, and an injection circuit 20 that injects a signal corresponding to a reference signal into the differential output oscillator 10. The injection circuit 20 includes a pulse generating section 30 that generates a current pulse corresponding to the reference signal, and an injection section 40 that generates an induced current in the differential output oscillator 10 when the current pulse generated by the pulse generating section 30 is input. Note that the injection-locked oscillator circuit 1 may or may not be configured on an integrated circuit, for example.

[0017] The differential output oscillator 10 is connected to the power supply voltage V DD is supplied from one end of resistor 11, and the power supply voltage V DD The circuit has a capacitor 12 connected in series with the resistor 11 at an end opposite to the resistor 11, two inductors 13 and 14 connected in series with the resistor 11 at the end of the resistor 11 on the capacitor 12 side, field effect transistors 15 and 16 having their drains connected to the ends of the inductors 13 and 14 opposite to the resistor 11, variable capacitors 17 and 18 connected to the drains of the field effect transistors 15 and 16, respectively, and a constant current source 19 connected to the sources of the field effect transistors 15 and 16. The gate of the field effect transistor 15 is connected to the drain of the field effect transistor 16, and the gate of the field effect transistor 16 is connected to the drain of the field effect transistor 15.

[0018] One LC resonator is formed by the inductor 13 and variable capacitor 17 connected in series, and another LC resonator is formed by the inductor 14 and variable capacitor 18 connected in series. Therefore, the differential output oscillator 10 has these two LC resonators, i.e., a pair of LC resonators. The resonant frequencies of the two LC resonators are assumed to be the same. That is, the inductances of the inductors 13 and 14 are assumed to be the same, and the capacitances of the variable capacitors 17 and 18 are assumed to be the same. The variable capacitors 17 and 18 are respectively connected to a control voltage V C The capacitance is changed by the control voltage V C The resonant frequency of the pair of LC resonators can be changed by changing the capacitance of the variable capacitors 17 and 18 using the control voltage V C The oscillation output signals are output from the nodes on the drain side of the field effect transistors 15 and 16.

[0019] 1 is merely an example, and any configuration of the differential output oscillator 10 is possible as long as it has a pair of LC oscillators and outputs an oscillation output signal of a predetermined oscillation frequency. In this embodiment, as described above, the oscillation frequency of the differential output oscillator 10 is controlled by the control voltage V C However, for example, the oscillation frequency of the differential output oscillator 10 may be constant and not change. In this case, for example, capacitors with fixed capacitance may be used instead of the variable capacitors 17 and 18.

[0020] The pulse generating unit 30 generates a current pulse according to a reference signal and includes an amplifier 31 that amplifies the reference signal, a capacitor 32 having one end connected to the amplifier 31, a resistor 33 and a variable resistor 34 connected to the other end of the capacitor 32, and a field-effect transistor 35 having a gate to which the output of a high-pass filter formed by the capacitor 32, the resistor 33, and the variable resistor 34 is input. The resistor 33 and the variable resistor 34 are connected in series, and the capacitor 32 and the gate of the field-effect transistor 35 are connected to a node between them. The cutoff frequency of the high-pass filter formed by the capacitor 32, the resistor 33, and the variable resistor 34 can be adjusted by the variable resistor 34. It is preferable that the cutoff frequency be adjusted as needed so that a desired pulse is output. The end of the resistor 33 opposite the variable resistor 34 is connected to a power supply voltage V DD is supplied. The end of the variable resistor 34 opposite to the resistor 33 is grounded. The source of the field effect transistor 35 is grounded, and the drain is connected to one end of the injection inductor 41 of the injection unit 40.

[0021] In FIG. 1, the pulse generating unit 30 is described as including a high-pass filter that generates one pulse in response to the rising edge of a reference signal, and a field-effect transistor 35 that is switched on / off in response to the output of the high-pass filter. However, this configuration of the pulse generating unit 30 is merely an example, and the configuration of the pulse generating unit 30 is not limited as long as it can generate a current pulse in response to a reference signal.

[0022] The reference signal is preferably a clock signal, for example, and is preferably a highly accurate signal. Therefore, the reference signal may be, for example, the output of a crystal oscillator. The frequency of the reference signal may be, for example, the same as the target oscillation frequency of the differential output oscillator 10, or may be 1 / n of the target oscillation frequency, where n is a positive integer. In the latter case, the frequency of pulses generated by the pulse generating unit 30 is 1 / n compared to the former case, so a small value of n is preferable. Even if the pulse frequency is reduced, as will be described later, if the injection unit 40 has a resonator, multiple consecutive pulses are generated in response to one pulse, thereby achieving appropriate injection locking. Furthermore, because pulses can be generated when the field-effect transistor 35 is turned on by a signal input to its gate, there is no need to use a reference signal with a large voltage corresponding to the oscillator's output amplitude, as in the conventional example.

[0023] The injection unit 40 includes an injection inductor 41 that generates induced currents in the pair of inductors 13 and 14 of the pair of LC oscillators of the differential output oscillator 10 when a current pulse generated by the pulse generation unit 30 is input to the injection unit 40, and a variable capacitor 42 connected in series with the injection inductor 41. The current pulse output from the pulse generation unit 30 is input to a node between the injection inductor 41 and the variable capacitor 42. The injection inductor 41 and the pair of inductors 13 and 14 of the pair of LC oscillators have coupling coefficients k1 and k2, respectively, and it is preferable that the coupling coefficients k1 and k2 have the same value. When the coupling coefficients k1 and k2 are equal, the injection inductor 41 can generate equal induced currents in the pair of inductors 13 and 14, thereby achieving well-balanced injection locking. While it is preferable that the coupling coefficients k1 and k2 are equal, they may differ by a factor of, for example, manufacturing error. It is also preferable that the directions of the induced currents generated in the inductors 13 and 14 due to mutual induction are opposite to each other. This allows current to be injected into one of the differential pair and extracted from the other. Therefore, it is preferable that the injection inductor 41 and the inductors 13 and 14 be shaped and arranged so as to generate the induced current described above. For example, the injection inductor 41 may be arranged inside the inductors 13 and 14, or vice versa, or the injection inductor 41 may be arranged adjacent to the inductors 13 and 14. When the injection-locked oscillator circuit 1 is configured as an integrated circuit, the injection inductor 41 and the inductors 13 and 14 may be arranged on adjacent layers of a multilayer board. Furthermore, in the injection-locked oscillator circuit 1 shown in FIG. 1, the two inductors 13 and 14 that form the differential can be considered to be electromagnetically coupled with a coupling coefficient k3, and therefore the three inductors 13, 14, and 41 can be considered to form a three-winding transformer.

[0024] The resonant frequency of the LC resonator formed by the injection inductor 41 and the variable capacitor 42 of the injection unit 40 is preferably equal to the oscillation frequency of the differential output oscillator 10. That is, the LC resonator of the injection unit 40 and the pair of LC resonators of the differential output oscillator 10 have a resonant frequency (f0=1 / (2π(L×C) 1 / 2 ) are preferably equal to each other. L and C are the inductance of the inductor and the capacitance of the capacitor, respectively, of the LC resonator. Therefore, for example, when the inductance of the injection inductor 41 is equal to the inductance of the inductors 13 and 14, the capacitance of the variable capacitor 42 is preferably equal to the capacitance of the variable capacitors 17 and 18. Therefore, as shown in FIG. 1, the variable capacitors 17, 18, and 42 may each be controlled by the same control voltage. On the other hand, the inductance of the injection inductor 41 may be different from the inductance of the inductors 13 and 14. In this case, it is usually preferable that the inductance of the injection inductor 41 be larger than the inductance of each of the inductors 13 and 14 to generate a larger induced current. By doing so, the phase noise reduction effect can be enhanced. On the other hand, the inductance of the injection inductor 41 may be smaller than the inductance of each of the inductors 13 and 14. In this case, the area of ​​the injection inductor 41 in the integrated circuit can be reduced, allowing the injection-locked oscillator circuit 1 to be a compact circuit. This is because the larger the inductance value, the larger the circuit area of ​​the inductor.

[0025] Next, the operation of the injection-locked oscillator circuit 1 according to this embodiment will be described. Referring to FIG. 1 , when a reference signal whose voltage varies as shown in waveform 51 is input to the high-pass filter of the pulse generating unit 30, one voltage pulse 52 is generated in response to the rising edge of the reference signal. Then, when the field-effect transistor 35 is turned on in response to the voltage pulse 52, one current pulse is generated at the drain side of the field-effect transistor 35. Since the field-effect transistor 35 is not turned on at the falling edge of the reference signal, the pulse generating unit 30 generates one pulse for each rising edge of the reference signal. Furthermore, the current pulse is input to an LC resonator formed by the injection inductor 41 and the variable capacitor 42, which generates a resonant waveform 53, causing periodic current pulses to flow through the injection inductor 41. As a result, periodic induced currents are generated in the inductors 13 and 14. Thus, the injection unit 40 including the LC resonator enables more efficient injection locking. Furthermore, when the coupling coefficients k1 and k2 are equal, equal and opposite induced currents are generated in the inductors 13 and 14, and a well-balanced current can be applied to the differential pair of the differential output oscillator 10.

[0026] As described above, according to the injection-locked oscillator circuit 1 of this embodiment, injection locking is performed by applying an induced current to the differential pair of the differential output oscillator 10 using electromagnetic coupling, so there is no need to apply a pulse signal with a voltage amplitude large enough to correspond to the amplitude of the oscillator to the transistor, as in the method of Non-Patent Document 2. Therefore, in the injection-locked oscillator circuit 1 of this embodiment, the pulse generating section 30 only needs to have a voltage large enough to turn on the field-effect transistor 35, so it can easily accommodate high-frequency operation of the differential output oscillator 10, for example.

[0027] Furthermore, when the coupling coefficients k1 and k2 of the injection inductor 41 and the inductors 13 and 14 are equal, it is possible to generate equal and opposite induced currents in the inductors 13 and 14, and it is possible to apply well-balanced currents to the differential pair of the differential output oscillator 10 without increasing the circuit size. Furthermore, because well-balanced current application can be achieved, it is possible to reduce the generation of common-mode noise.

[0028] Furthermore, since the injection unit 40 has an LC resonator, in response to the input of one current pulse from the pulse generation unit 30, induced currents corresponding to multiple current pulses can be generated in the differential pair of the differential output oscillator 10, making it possible to realize efficient current application.

[0029] Furthermore, if the inductance of the injection inductor 41 is made larger than the inductance of the inductors 13 and 14 of the differential output oscillator 10, a larger induced current can be generated in the differential output oscillator 10, thereby improving the phase noise reduction effect. On the other hand, if the inductance of the injection inductor 41 is made smaller than the inductance of the inductors 13 and 14 of the differential output oscillator 10, the area of ​​the injection inductor 41 in the integrated circuit can be made smaller, and the circuit area of ​​the injection-locked oscillator circuit 1 can be made smaller.

[0030] Next, a modification of the injection-locked oscillator circuit 1 according to this embodiment will be described. 2 includes two injection inductors 41a and 41b connected in series instead of the single injection inductor 41 of the injection unit 40. In this case, too, it is preferable that the two injection inductors 41a and 41b generate equal but opposite induced currents in the inductors 13 and 14. Therefore, for example, it is preferable that the inductances of the injection inductors 41a and 41b are equal, and that the coupling coefficients k1 and k2 are also equal. As a result, as long as equal but opposite induced currents can be generated in the differential pair of the differential output oscillator 10, the number of inductors included in the injection unit 40 may be one or more.

[0031] 3, the LC resonator of the injection unit 40 is provided with a capacitor 43 having a fixed capacitance instead of the variable capacitor 42. Note that in the injection locked oscillation circuit 1 of FIG. 3, instead of connecting one end of the injection inductor 41 of the injection unit 40 to the differential output oscillator 10, the power supply voltage V DD is also supplied. In this case, for example, the inductance of the injection inductor 41 may be set to a desired value, and the capacitance of the capacitor 43 may be selected so that the resonant frequency of the LC resonator of the injection unit 40 matches the oscillation frequency of the differential output oscillator 10. In this case, it is preferable that the oscillation frequency of the differential output oscillator 10 does not change.

[0032] In the injection-locked oscillator circuit 1 of FIG. 4, the LC resonator of the injection unit 40 is provided with a switch 44 and N capacitors 45-1 to 45-N with fixed capacitances, instead of the fixed capacitor 43 of FIG. 3. N is an integer of 2 or more. When the N capacitors 45-1 to 45-N are not to be distinguished from one another, they may be referred to as capacitors 45. The N capacitors 45-1 to 45-N each have a different capacitance. In the differential output oscillator 10, a control voltage V CWhen the oscillation frequency is changed in response to V, the capacitor 45 is selected by the switch 44 so that the oscillation frequency matches the resonant frequency of the LC resonator of the injection unit 40. Note that the injection-locked oscillator circuit 1 of FIG. 4 may include variable capacitors whose capacitance changes in response to a control voltage, instead of the switch 44 and the N capacitors 45. C The capacitance of the variable capacitor may be controlled by a control voltage different from that of the variable capacitor, so that the resonant frequency of the LC resonator of the injection unit 40 matches the oscillation frequency. In this way, the capacitance of the capacitor connected in series to the injection inductors 41, 41a, and 41b in the injection unit 40 may be changed so that the oscillation frequency matches the resonant frequency of the LC resonator of the injection unit 40.

[0033] Furthermore, in this embodiment, the case where the resonant frequency of the LC resonant circuit of the injection unit 40 matches the oscillation frequency of the differential output oscillator 10 has been mainly described, but this is not necessarily the case. The resonant frequency of the injection unit 40 may be M times the oscillation frequency (M is an integer equal to or greater than 1). Therefore, for example, when the capacitance of a capacitor constituting the LC resonant circuit of the injection unit 40 is changed in response to a change in the oscillation frequency, the capacitance may be changed so that the resonant frequency becomes M times the oscillation frequency. Note that, although the effect of injection locking is strongest when M is 1, the effect of injection locking can also be obtained even when M is 2 or greater.

[0034] The injection-locked oscillator circuit 1 of Fig. 5 is the injection-locked oscillator circuit 1 of Fig. 3, except that the injection unit 40 does not include the capacitor 43. In this way, when the injection unit 40 does not include a capacitor, when one current pulse is input, only an induced current corresponding to the one current pulse is generated in the inductors 13 and 14, and the efficiency of injection locking is lower than that of the injection-locked oscillator circuit 1 of Figs. 1 to 4. However, it still has the advantages of being able to easily accommodate high-frequency operation of the differential output oscillator 10 and being able to reduce common-mode noise by making the coupling coefficients k1 and k2 equal. Another advantage is that the inductance of the inductor 41 can be set regardless of the oscillation frequency of the differential output oscillator 10, thereby increasing the degree of freedom in design.

[0035] Furthermore, it goes without saying that any of the above modifications may be combined. For example, in the injection-locked oscillator circuits 1 of Figures 1, 2, and 4, the injection unit 40 may not include a capacitor of the LC resonator. Furthermore, in the injection-locked oscillator circuits 1 of Figures 3 to 5, the injection inductor 41 of the injection unit 40 may be configured with two injection inductors 41a and 41b, similar to the injection-locked oscillator circuit 1 of Figure 2.

[0036] Next, a simulation result of the injection-locked oscillator circuit 1 according to this embodiment will be described. [Simulation 1] In this simulation, the injection locking range depending on whether or not the injection unit 40 has an LC resonator was determined for each of k1 = k2 = 0.1, 0.2, and 0.3. When the injection unit 40 has an LC resonator, the injection-locked oscillator circuit 1 has the circuit configuration shown in FIG. 2. The oscillation frequency and the resonant frequency of the injection unit 40 were set to 10 GHz. When the injection unit 40 does not have an LC resonator, the injection-locked oscillator circuit 1 has the circuit configuration shown in FIG. 2 without the variable capacitor 42. The results of this simulation are shown in the following table. [Table 1]

[0037] From the results of this simulation shown in the table above, it was confirmed that, regardless of the coupling coefficient, when the injection section 40 has an LC resonator, the injection locking range is more than doubled, and more efficient injection locking can be achieved.

[0038] [Simulation 2] In this simulation, the inductances of the inductors 13 and 14 of the differential output oscillator 10 were fixed at 0.5 nH, and the inductances of the injection inductors 41a and 41b were varied from 0.5 nH to 1.0 nH, and the injection locking range was determined. The injection-locked oscillator circuit 1 was configured as shown in FIG. 2 , with the injection unit 40 not including the variable capacitor 42. The coupling coefficients k1 and k2 were fixed at 0.1. The oscillation frequency was set to 10 GHz. The results of this simulation are shown in FIG. 6. As can be seen from FIG. 6, even when the injection unit 40 does not include a capacitor and does not include an LC resonator, increasing the inductances of the injection inductors 41a and 41b of the injection unit 40 can provide a larger induced current to the differential output oscillator 10, thereby improving the injection locking effect.

[0039] In the above-described embodiments, each process or function may be realized by centralized processing by a single device or a single system, or may be realized by distributed processing by multiple devices or multiple systems.

[0040] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0041] 1. Injection-locked oscillator circuit 10 Differential Output Oscillator 43, 45, 45-1 to 45-N capacitors 13, 14 Inductors 42 Variable Capacitor 20 Injection circuit 30 Pulse generation unit 40 Injection part 41, 41a, 41b Injection inductors

Claims

1. a differential output oscillator having a pair of LC oscillators and outputting an oscillation output signal having an oscillation frequency according to a control voltage; an injection circuit that injects a signal corresponding to a reference signal into the differential output oscillator; The injection circuit a pulse generating unit that generates a current pulse according to the reference signal; an injection unit having an injection inductor that generates an induced current in a pair of inductors in the pair of LC oscillators by receiving the current pulse generated by the pulse generation unit, and a capacitor connected in series with the injection inductor; An injection-locked oscillator circuit, wherein the capacitance of the capacitor is changed so that the resonant frequency of a resonator formed by the injection inductor and the capacitor becomes M times (M is an integer equal to or greater than 1) the oscillation frequency of the differential output oscillator.

2. 2. The injection-locked oscillator circuit according to claim 1, wherein the inductance of said injection inductor is greater than the inductance of each of said pair of inductors.

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