JP2005057626A - Injection-locked oscillator and high-frequency communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection-locked oscillator which is stable and has a high degree of multiplication and has a simple circuit configuration, and whose power consumption is low. <P>SOLUTION: The injection-locked oscillator has an amplification circuit 21 and a parallel feedback circuit 20, and has an input-side transmission line 22 which has an approximately quarter electric length with respect to the wavelength of a fundamental oscillation frequency thereof. The input-side transmission line 22 has one end 22B connected to the input-side connection part P5 of the amplification circuit 21 and has the other end 22A grounded through an input-side capacitor 23. A signal having 1/m (m is an integer equal to or larger than two) frequency of the fundamental oscillation frequency is injected to a connection part P1 between the input-side capacitor 23 and the input-side transmission line 22. The input-side transmission line 22 presents high impedance with respect to a fundamental oscillation signal at a connection point P2 with the amplification circuit 21, which becomes nearly the equivalent value to that in a state nothing is connected to the input side connection part with respect to the fundamental oscillation signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection locked oscillator and a high frequency communication device.

  In recent years, with an increase in the amount of information, personal communication that wirelessly transmits high-speed, large-capacity analog / digital information using a high-frequency carrier wave such as a microwave or a millimeter wave has attracted attention.

  In such communication, a small and lightweight microwave / millimeter wave signal generator with high frequency stability and low phase noise is required. One technique for constructing such a microwave / millimeter wave signal generator is an injection locked oscillator.

  As an example of a conventional injection-locked oscillator, a technique described in JP-A-7-221546 is shown in FIG. In FIG. 6, 10 is an irreversible four-terminal circuit, 1 is a first input terminal, 2 is a second input terminal, 3 is a first output terminal, and 4 is a second output terminal. .

  The injection signal input from the first input terminal 1 to the four-terminal circuit 10 is distributed only to the first output terminal 3 and the second output terminal 4. On the other hand, a signal input from the second input terminal 2 to the four-terminal circuit 10 is distributed only to the first output terminal 3 and the second output terminal 4, and the first input terminal 1 and the second input terminal are distributed. No signal is transmitted between the first output terminal 3 and the second output terminal 4.

  The amplifier 11 included in this injection-locked oscillator has an input terminal 5 and an output terminal 6 with a voltage gain A and a phase shift amount θ. The input terminal 5 of the amplifier 11 is connected to the first output terminal 3 of the 4-terminal circuit 10, and the output terminal 6 of the amplifier 11 is connected to the second input terminal 2 of the 4-terminal circuit 10. .

  Here, if the input signal from the first input terminal 1 or the second input terminal 2 is distributed in phase with a voltage ratio of 1/2 to the first output terminal 3 and the second output terminal 4. Then, the following expression (1) is established.

_{V out / V in = 1 /} (2-A · e -jθ) ...... (1)
In the above equation (1), V _in and V _out are an input voltage and an output voltage, respectively. Here, when the voltage gain A of the amplifier 11 is 2 or more and the phase shift amount θ is in the vicinity of an integral multiple of π (radian), the second input terminal 2, the first output terminal 3, and the input terminal 5, in the oscillation loop of the output terminal 6 and the second input terminal 2, the oscillation rises, and the gain A of the amplifier 11 is suppressed as the oscillation level rises, and the oscillation is stabilized at the gain A = 2.

  Here, when the above-described operation of the four-terminal circuit 10 is established at an arbitrary frequency, if a highly stable and low-phase noise signal is input from the first input terminal 1 to the four-terminal circuit 10 as an injection signal, One half is input to the amplifier 11 via the first output terminal 3, and harmonics are generated by the nonlinearity of the oscillating amplifier 11.

  When one of the harmonics is in the vicinity of the oscillation frequency, a wave due to the oscillation and the harmonic are generated, and the oscillation state of the amplifier 11 is changed so that the wave becomes zero, and the injection is performed. The oscillation state is synchronized with the signal.

The oscillation output of the amplifier 11 is output to the second output terminal 4 via the second input terminal 2. On the other hand, the oscillation output does not appear at the first input terminal 1 which is a signal input terminal due to the irreversibility of the four-terminal circuit 10. Therefore, even if the first input terminal 1 is in a mismatched state, a part of the oscillation output is not reflected by the first input terminal 1 and is reinjected into the oscillation loop. There is no. In addition, since the reflected wave at the second output terminal 4 does not appear at any other terminal, the reflected wave is not reinjected into the oscillation loop. In other words, this injection-locked oscillator is configured not to be affected by an external circuit.
JP-A-7-221546

  By the way, in the prior art described with reference to FIG. 6, at least four active elements such as field effect transistors are required in order to specifically realize the irreversible four-terminal circuit. For this reason, there existed a subject that power consumption became large.

  Accordingly, an object of the present invention is to provide an injection-locked oscillator that is stable, has a high multiplication order, has a simple circuit configuration, and has low power consumption.

In order to achieve the above object, an injection locking oscillator of the present invention is an oscillator having at least an amplifying unit and a parallel feedback unit connected in parallel to the amplifying unit,
An input-side transmission line having an electrical length of approximately 1/4 with respect to the wavelength of the fundamental oscillation frequency, and an input-side capacitor;
One end of the transmission line on the input side is connected to the connection part on the input side of the amplification unit and the parallel feedback unit, and the other end of the transmission line on the input side is grounded via the capacitor on the input side. ,
In addition, an input terminal into which a signal is injected is connected to a connection portion between the input-side capacitor and the input-side transmission line.

  In the injection-locked oscillator of the present invention, the transmission line on the input side has a high impedance with respect to the signal of the fundamental oscillation frequency (that is, the fundamental oscillation signal) at the connection portion on the input side with the amplifier, and the basic transmission line This is almost equivalent to the case where nothing is connected to the connection portion on the input side with respect to the oscillation signal. Therefore, the fundamental oscillation signal is hardly output from the input terminal, and the oscillation state is not affected even if a circuit block having any impedance is connected to the input terminal. Therefore, according to the injection-locked oscillator of the present invention, the number of active elements can be reduced as compared with the prior art, and stable oscillation can be achieved with a simple circuit configuration.

The injection-locked oscillator of one embodiment includes an output-side transmission line having an electrical length of approximately ¼ with respect to the wavelength of the fundamental oscillation frequency, and an output-side capacitor.
One end of the output-side transmission line is connected to the output-side connection between the amplification unit and the parallel feedback unit, and the other end of the output-side transmission line is grounded via the output-side capacitor. ,
In addition, a DC bias terminal for applying a DC voltage was connected to a connection portion between the output-side capacitor and the output-side transmission line.

  In this embodiment, the transmission line on the output side has a high impedance with respect to the fundamental oscillation frequency at the connection portion on the output side with the amplification unit. Therefore, it is almost equivalent to nothing being connected to the connection portion on the output side as seen from the amplifier. Therefore, according to this embodiment, even if a circuit block having any impedance is connected to the connection portion of the output-side capacitor and the output-side transmission line, stable oscillation without affecting the oscillation state Is possible.

  In the injection-locked oscillator of one embodiment, the output-side capacitor has an absolute value of reactance with respect to the fundamental oscillation frequency of 20 ohms or less and 1 / m of the fundamental oscillation frequency (m is 2 or more). The capacity is set so that the absolute value of the reactance with respect to the frequency of (integer) is 40 ohms or more.

  In this embodiment, by setting the capacitance of the output-side capacitor within the above range, the decibel value of the reflection coefficient at the input terminal is set to 0 or less at the frequency of the injection signal injected into the input terminal. be able to. For this reason, according to this embodiment, the matching circuit for injection signals can be configured easily.

  When the absolute value of the reactance of the output-side capacitor with respect to the fundamental oscillation frequency exceeds 20 ohms, the impedance at the fundamental oscillation frequency at the connection portion between the output-side transmission line and the amplification unit is reduced and amplified. Part of the oscillation signal at the part is reflected to the input side, and the output to the output side decreases. On the other hand, when the absolute value of the reactance of the output-side capacitor with respect to a frequency of 1 / m (m is an integer of 2 or more) of the fundamental oscillation frequency is less than 40 ohms, the decibel value of the reflection coefficient at the input terminal is Over zero.

  Moreover, the high frequency communication apparatus of one Embodiment was provided with the said injection locking oscillator. In the high-frequency communication device of this embodiment, the above-described injection locking oscillator is provided, so that a multiplication operation can be equivalently performed with a very simple configuration compared to the conventional one, and the device can be reduced in size, cost, and cost. Power consumption can be reduced.

  In the injection-locked oscillator of the present invention, the transmission line on the input side has a high impedance with respect to the signal of the fundamental oscillation frequency (that is, the fundamental oscillation signal) at the connection point on the input side with the amplifier, and nothing is connected. It is almost equivalent to not. Therefore, the fundamental oscillation signal is hardly output from the input terminal, and the oscillation state is not affected even if a circuit block having any impedance is connected to the input terminal. Therefore, according to the injection-locked oscillator of the present invention, the number of active elements can be reduced as compared with the prior art, and stable oscillation can be achieved with a simple circuit configuration.

  Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

(First embodiment)
FIG. 1 shows a configuration of a first embodiment of an injection locked oscillator according to the present invention. The first embodiment includes a parallel feedback circuit 20 serving as a parallel feedback unit, an amplifier circuit 21 serving as an amplifier, an input transmission line 22, and an input capacitor 23. The parallel feedback circuit 20 is connected in parallel to the amplifier circuit 21 at a connection part P2 on the input side and a connection part P5 on the output side.

  The transmission line 22 on the input side has an electrical length of about 1/4 (1/4) with respect to the wavelength of the fundamental oscillation frequency f1 of the fundamental oscillation signal of the oscillator. One end 22B of the transmission line 22 on the input side is connected to a connection portion P2 between the parallel feedback circuit 20 and the input side of the amplifier circuit 21. The other end 22 </ b> A of the input side transmission line 22 is grounded via the input side capacitor 23.

  An input terminal 24 is connected to the connection portion P1 between the input-side capacitor 23 and the input-side transmission line 22. A signal having a frequency of 1 / m (m is an integer of 2 or more) of the basic oscillation frequency fo is injected into the input terminal 24.

  In the first embodiment, the phase difference between the input signal and the output signal of the amplifier circuit 21 is adjusted by the parallel feedback circuit 20 so that positive feedback is applied at the fundamental oscillation frequency. As a result, in the first embodiment, oscillation rises near the fundamental oscillation frequency, and with the increase in the oscillation level, the gain of the amplifier circuit 21 is suppressed, the oscillation is stabilized, and the oscillation signal is output from the output terminal 25. The

  On the other hand, the transmission line 22 on the input side has an electrical length of approximately ¼ with respect to the wavelength of the fundamental oscillation frequency, and the other end 22A is grounded via the capacitor 23 on the input side. For this reason, in the connection part P2 between the transmission line 22 on the input side and the parallel feedback circuit 20 and the amplifier circuit 21, the transmission line 22 on the input side has a high impedance with respect to the fundamental oscillation signal at the fundamental oscillation frequency. 20 and the amplifying circuit 21, it is almost equivalent to nothing being connected to the input side connecting portion P2. Therefore, the basic oscillation signal is hardly output from the input terminal 24. In the first embodiment, even if a circuit block having any impedance is connected to the input terminal 24, stable oscillation is possible without affecting the oscillation state.

  Further, when an injection signal having a frequency of 1 / m (m is an integer of 2 or more) of the fundamental oscillation frequency is input from the input terminal 24, this injection signal is input to the amplification circuit 21, and the amplification circuit 21 during oscillation is supplied. Harmonics occur due to non-linearity. The oscillating state of the amplifying circuit 21 is changed so that the swell is caused by the m-th harmonic of the harmonics and the fundamental oscillation signal having the fundamental oscillation frequency, and the swell is zero, and the injection signal is changed. Oscillation state synchronized with.

  Therefore, according to the injection-locked oscillator of the first embodiment, an output signal obtained by multiplying the injection signal by m (m is an integer of 2 or more) can be obtained with a very simple configuration. In addition, the purity of the output signal is the purity of the injection signal, and the stability of the output signal is m times the purity of the injection signal. Therefore, if the injection signal source is configured with a highly stable and low noise signal, it is possible to obtain a highly stable and low noise output signal in the quasi-millimeter wave / millimeter wave band.

(Second Embodiment)
Next, FIG. 2 shows a configuration of a second embodiment of the injection locking oscillator of the present invention. The second embodiment is different from the first embodiment described above in that an output side bias circuit B1 is provided in addition to the configuration of the first embodiment shown in FIG. Therefore, in the second embodiment, differences from the first embodiment will be mainly described.

  The output-side bias circuit B1 includes an output-side transmission line 26, an output-side capacitor 27, an inductor 28, and a capacitor 29.

  The transmission line 26 on the output side has an electrical length of about 1/4 with respect to the wavelength of the fundamental oscillation frequency of the fundamental oscillation signal oscillated by this oscillator. One end 26A of the transmission line 26 on the output side is connected to the output side of the amplifier circuit 21 via the connection part P3 and the connection part P5 on the output side. The other end 26 </ b> B of the transmission line 26 on the output side is connected to the output side capacitor 27 at the connection portion P <b> 4 and is grounded via the output side capacitor 27.

  Further, a DC bias terminal 30 is connected to a connection portion P4 between the output-side capacitor 27 and the output-side transmission line 26 via an inductor 28. The DC bias terminal 30 is connected to a DC power source (not shown) for applying a DC voltage. The inductor 28 functions as a choke that allows only a direct current to pass therethrough. The capacitor 29 functions as a decoupling capacitor that short-circuits noise of the DC power supply (not shown) connected to the DC bias terminal 30.

  In this second embodiment, the output-side capacitor 27 has an absolute value of reactance with respect to the fundamental oscillation frequency of 20 ohms or less and a frequency of 1 / m (m is an integer of 2 or more) of the fundamental oscillation frequency. The capacity is set so that the absolute value of the reactance is 40 ohms or more.

  Therefore, at the connection portion P3 between the output-side transmission line 26 and the parallel feedback circuit 20 and the amplifier circuit 21, the output-side transmission line 26 has a high impedance with respect to the fundamental oscillation frequency. Therefore, it is almost equivalent to the basic oscillation signal that nothing is connected to the connection portion P3. For this reason, the transmission line 26 on the output side does not affect the oscillation state of the amplifier circuit 21.

  On the other hand, the output-side capacitor 27 has an absolute value of reactance of 40 ohms or more for an injection signal having a frequency of 1 / m (m is an integer of 2 or more) of the fundamental oscillation frequency. The capacitance of the output-side capacitor 27 is set to be small. Therefore, the transmission line 26 on the output side appears to have a relatively high impedance at the connection portion P3 between the parallel feedback circuit 20 and the amplifier circuit 21.

  As described above, in the second embodiment, the parallel feedback circuit 20 serving as a positive feedback circuit is provided, and the output side of the amplifier circuit 21 has a predetermined frequency (a frequency that is 1 / m of the basic oscillation frequency). If the impedance is high, the decibel value of the reflection coefficient of the input terminal 24 on the input side of the amplifier circuit 21 at the predetermined frequency is 0 or less. As a result, the input matching circuit for the injection signal from the input terminal 24 can be easily configured with only the reactive element.

  On the other hand, if the output-side capacitor 27 is set to a very large capacity as compared with the smaller capacity, the output side of the amplifier circuit 21 is very high with respect to the frequency of the injection signal from the input terminal 24. Low impedance. In this case, the decibel value of the reflection coefficient at the input terminal 24 on the input side of the amplifier circuit 21 becomes 0 or more, and a matching circuit for the injection signal from the input terminal 24 cannot be configured, and a large reflected wave is generated in the injection signal source. As a result, the injection signal source may malfunction.

  The function of the output-side capacitor 27 will be described in detail using a more specific example in the following third embodiment.

(Third embodiment)
Next, FIG. 3 shows a third embodiment of the injection locking oscillator of the present invention. FIG. 3 shows the concept of the first and second embodiments shown in FIGS. 1 and 2 in a more specific circuit configuration.

  In the third embodiment, the fundamental oscillation frequency fo is 29.5 GHz, and the frequency of the injection signal is 3.6875 GHz which is an eighth harmonic of the fundamental oscillation frequency fo.

  In the third embodiment, the amplification circuit AMP1 that is an amplification unit and the parallel feedback unit PF form a positive feedback circuit C1. The amplifier circuit AMP1 includes an active element 101, a transmission line 106 connected to the input side of the active element 101, and a transmission line 102 connected to the output side of the active element 101. The active element 101 is composed of an npn bipolar transistor. The base of the transistor, which is the active element 101, is connected to the transmission line 106, the collector of the active element 101 is connected to the transmission line 102, and the emitter is grounded.

  The parallel feedback unit PF includes a transmission line 103, a capacitor 104, and a transmission line 105. The transmission line 103, the capacitor 104, and the transmission line 105 are connected in series in order to form a parallel feedback unit PF. The positive feedback circuit C1 self-oscillates in the vicinity of 29.5 GHz.

  The transmission line 102 of the amplifier circuit AMP1 is connected to a connection part P37, and this connection part P37 is connected to an output terminal 118 via a capacitor 114. The connection part P37 is connected to the transmission line 103 via the connection part P33.

  In addition, one end 109B of the transmission line 109 as the transmission line on the input side is connected to the connection part P32 between the transmission line 105 of the parallel feedback unit PF and the transmission line 106 of the amplifier circuit AMP1. The other end 109A is connected to a capacitor 110 as a capacitor on the input side at a connection portion P31. This capacitor 110 is grounded.

  The connection portion P31 between the input-side capacitor 110 and the input-side transmission line 109 is connected to the input terminal 117 via the capacitor 113. In addition, a resistor 112 and a resistor 111 are connected to a connection portion P34 between the capacitor 113 and the connection portion P31. The resistor 112 is grounded, and the resistor 111 is connected to a DC bias terminal 119 to which a DC bias voltage to the active element 101 is applied.

  The input-side transmission line 109 and the input-side capacitor 110 in the third embodiment correspond to the input-side transmission line 22 and the input-side capacitor 23 in FIGS. 1 and 2, and their functions are the same as those in the first embodiment. This is the same as described in the form. The capacitor 113 has a function of cutting DC (direct current), and at the same time, is set to an optimum capacitance value together with the capacitor 110, thereby matching with a desired frequency of an injection signal injected from the input terminal 117. I can take it.

  In the third embodiment, a capacitor 116 is connected to the DC bias terminal 119, and the capacitor 116 is grounded. In addition, an inductor 115 is connected to the bias terminal 119, and the inductor 115 is grounded via a capacitor 108 which is an output side capacitor. The other end 107A of the transmission line 107, which is the output transmission line, is connected to the connection point P36 between the output-side capacitor 108 and the inductor 115, and the one end 107B of the output-side transmission line 107 is connected to the parallel connection line. The transmission line 103 of the feedback circuit PF and the transmission line 102 of the amplifier circuit AMP1 are connected to a connection part P33.

  The output-side transmission line 107, the output-side capacitor 108, the inductor 115, and the capacitor 116 constitute an output-side bias circuit B31, and this output-side bias circuit B31 is the output-side bias in the second embodiment. This has the same function as the bias circuit B1.

  That is, the output-side transmission line 107, the output-side capacitor 108, the inductor 115, and the capacitor 116 in the third embodiment are respectively the output-side transmission line 26 and the output-side transmission line 26 in the second embodiment shown in FIG. It corresponds to the capacitor 27, the inductor 28, and the capacitor 29, and their functions are the same as those described in the second embodiment.

  In the third embodiment, a DC bias voltage is applied from the DC bias terminal 119 for the bias to the active element 101. The DC bias voltage is applied to the active element 101 via the inductor 115 and the transmission line 107 on the output side. 101 is applied to the output side. Further, the DC bias voltage from the DC bias terminal 119 is applied to the input side of the active element 101 after being divided into an optimum voltage by the resistor 111 and the resistor 112.

  Next, the effect of the output-side capacitor 108 (corresponding to the capacitor 27 in FIG. 2) in the third embodiment will be described with reference to FIG. In FIG. 4, the frequency characteristics of the reflection coefficient S11 (dB) at the input terminal 117 when the capacitance of the output-side capacitor 108 is 0.4 pF, 1 pF, and 2 pF are shown by characteristic curves C1, C2, and C3, respectively. It was.

  When the capacitance of the output-side capacitor 108 is 0.4 pF, the reactance of the capacitor 108 is 108Ω with respect to (1/8) fo, which is one-eighth the fundamental oscillation frequency fo, 13Ω with respect to the fundamental oscillation frequency fo. Further, when the capacitance of the output-side capacitor 108 is 1 pF, the reactance of the capacitor 108 is 43Ω with respect to (1/8) fo which is 1/8 of the fundamental oscillation frequency fo. It is 5.2Ω with respect to the frequency fo. Further, when the capacitance of the output-side capacitor 108 is 2 pF, the reactance of the capacitor 108 is 22Ω with respect to the frequency (1/8) fo of the eighth of the fundamental oscillation frequency fo, and the fundamental oscillation frequency fo Is 2.6Ω.

  Referring to FIG. 4, as shown by the characteristic curve C1, when the capacitance of the output-side capacitor 108 is 0.4 pF, a large reflection loss is obtained around the frequency (3.6875 GHz) of the injection signal. However, as the capacitance of the output-side capacitor 108 increases to 1 pF and 2 pF, the reflection loss deteriorates (decreases) in the vicinity of the frequency of the injection signal as indicated by the characteristic curves C2 and C3, and the capacitance is 2 pF. In the case of the characteristic curve C3, it becomes a reflection gain.

  Therefore, in the range where the capacitance of the output-side capacitor 108 is changed as described above, the smaller the capacitance of the output-side capacitor 108, the easier the matching of the injection signal at the input terminal 117.

  However, if the capacitance of the output-side capacitor 108 is too small, the absolute value of the reactance of the capacitor 108 with respect to the basic oscillation frequency fo increases, and the basic point at the connection point P33 between the output-side transmission line 107 and the amplifier circuit AMP1. Impedance at the oscillation frequency is reduced. For this reason, a part of the oscillation signal in the amplifier circuit AMP1 of the third embodiment is reflected to the input side, and the output from the output terminal 118 decreases. Accordingly, the capacitance of the output-side capacitor 108 is such that the absolute value of the reactance with respect to the fundamental oscillation frequency fo is 20Ω or less and the reactance with respect to a frequency of 1 / m (m is an integer of 2 or more) of the fundamental oscillation frequency fo. It is desirable to set the absolute value within a range of 40Ω or more.

  In the third embodiment, the active element 101 included in the amplifier circuit AMP1 that is an amplifier unit is an npn bipolar transistor. However, the amplifier circuit AMP1 may be formed of another active element such as a pnp transistor or a field effect transistor. Good. In the third embodiment, the frequency of the injection signal is 1/8 of the fundamental oscillation frequency. However, the frequency of the injection signal may be 1 / m of the fundamental oscillation frequency (m is an integer of 2 or more). .

(Fourth embodiment)
Next, FIG. 5 shows the configuration of a high-frequency communication apparatus as a fourth embodiment of the present invention. This high-frequency communication apparatus includes a transmitter 901 and a receiver 902, and includes injection locking oscillators 806 and 816 having the same configuration as that of the third embodiment.

  As shown in the block diagram of FIG. 5, the transmitter 901 includes a modulation signal source 801, a harmonic mixer 802, a band pass filter 803, a power amplifier 804, an antenna 805, an injection locked oscillator 806, and a reference signal source 807. The A harmonic mixer 802, a band-pass filter 803, a power amplifier 804, and an antenna 805 are connected in order to the modulation signal source 801, and an injection locking oscillator 806 and a reference signal source 807 are connected to the harmonic mixer 802 in order.

  On the other hand, the receiver 902 includes a tuner 811, a harmonic mixer 812, a band pass filter 813, a low noise amplifier 814, an antenna 815, an injection locking oscillator 816, and a reference signal source 817. A low noise amplifier 814, a band-pass filter 813, a harmonic mixer 812, and a tuner 811 are connected to the antenna 815 in this order, and an injection locking oscillator 816 and a reference signal source 817 are connected to the harmonic mixer 812 in order.

  The injection-locked oscillators 806 and 816 have a basic oscillation frequency (fo) of 29.5 GHz. The reference signal sources 807 and 817 output a signal of 3.6875 GHz which is 1/8 sub-harmonic of the fundamental oscillation frequency (fo).

  That is, the transmitter 901 and the receiver 902 respectively inject a signal having a frequency of 3.6875 GHz from the reference signal sources 807 and 817 to the injection locking oscillators 806 and 816, and from the injection locking oscillators 806 and 816, A 29.5 GHz signal that is an eighth harmonic of the injected signal is output.

  On the other hand, the frequency of the intermediate frequency signal generated by the modulation signal source 801 of the transmitter 901 occupies between 1 GHz and 2 GHz, and this intermediate frequency signal is input to the intermediate frequency signal terminal of the harmonic mixer 802. The local oscillation signal output from the injection locked oscillator 806 is a sine wave having a frequency of 29.5 GHz. This local oscillation signal is input to the local oscillation signal terminal of the harmonic mixer 802.

  The intermediate frequency signal and the local oscillation signal are mixed in a harmonic mixer 802. Of the signals generated from the harmonic mixer 802, only a high frequency signal having a frequency between 60 GHz and 61 GHz passes through the band pass filter 803, is input to the power amplifier 804, is amplified, and is radiated from the antenna 805 as a high frequency radio wave 820. The

  This high frequency radio wave 820 is received by the antenna 815, becomes a high frequency signal of the receiver 902, and is amplified by the low noise amplifier 814. Further, the signal passes through the band pass filter 813 and is input to the high frequency signal terminal of the harmonic mixer 812.

  On the other hand, a sine wave signal having a frequency of 29.5 GHz output from the injection locking oscillator 816 is input to the local oscillation signal terminal of the harmonic mixer 812. Then, the high-frequency signal is mixed with a local oscillation signal (that is, a sine wave signal having a frequency of 29.5 GHz input to the local oscillation signal terminal) inside the harmonic mixer 812, and is again intermediate between the frequencies of 1 GHz to 2 GHz. Converted to a frequency signal. This intermediate frequency signal is input from the harmonic mixer 812 to the tuner 811 and converted into desired information.

  Note that the harmonic mixers 802 and 812 can have exactly the same configuration. The power amplifier 804 and the low noise amplifier 814, the antennas 805 and 815, the injection locking oscillators 806 and 816, and the reference signal sources 807 and 817 can have the same configuration.

  Since the reference signal sources 807 and 817 output signals in the 3 GHz band, the highly stable and low phase noise reference signal sources 807 and 817 can be easily configured by conventional microwave technology. On the other hand, the injection-locked oscillators 806 and 807 can equivalently perform a multiplication operation of 8 with a very simple configuration, contributing to downsizing, cost reduction, and power consumption of the apparatus.

1 is a block diagram showing a configuration of a first embodiment of an injection locked oscillator according to the present invention. FIG. It is a block diagram which shows 2nd Embodiment of the injection locking oscillator of this invention. It is a circuit diagram which shows 3rd Embodiment of the injection locking oscillator of this invention. It is a characteristic view which shows the frequency dependence of the reflective characteristic in the input terminal (injection terminal) of the said 3rd Embodiment. It is a block diagram which shows the structure of the high frequency communication apparatus as 4th Embodiment provided with the injection locking oscillator of the said 3rd Embodiment. It is a block diagram which shows the conventional injection locking oscillator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Parallel feedback circuit 21 Amplifier circuit 22 Input side transmission line 26 Output side transmission line 23,110 Input side capacitor 27,108 Output side capacitor 29,104,113,114,116 Capacitor 28,115 Inductor 24,117 Input terminal 25,118 Output terminal 30,119 DC bias terminal 101 Active element 102,103,105,106 Transmission line P1-P5, P31-P37 Connection part

Claims (4)

An oscillator having at least an amplification unit and a parallel feedback unit connected in parallel to the amplification unit,
An input-side transmission line having an electrical length of approximately 1/4 with respect to the wavelength of the fundamental oscillation frequency, and an input-side capacitor;
One end of the transmission line on the input side is connected to the connection part on the input side of the amplification unit and the parallel feedback unit, and the other end of the transmission line on the input side is grounded via the capacitor on the input side. ,
An injection-locked oscillator comprising an input terminal for injecting a signal connected to a connection portion between the input-side capacitor and the input-side transmission line. The injection-locked oscillator according to claim 1,
An output-side transmission line having an electrical length of approximately ¼ of the wavelength of the fundamental oscillation frequency, and an output-side capacitor;
One end of the output-side transmission line is connected to the output-side connection between the amplification unit and the parallel feedback unit, and the other end of the output-side transmission line is grounded via the output-side capacitor. ,
An injection-locked oscillator comprising a DC bias terminal for applying a DC voltage connected to a connection portion between the output-side capacitor and the output-side transmission line. The injection-locked oscillator according to claim 2,
The output-side capacitor has an absolute value of reactance with respect to the fundamental oscillation frequency of 20 ohms or less, and an absolute value of reactance with respect to a frequency of 1 / m (m is an integer of 2 or more) of the fundamental oscillation frequency. An injection-locked oscillator characterized in that a capacity is set so as to be greater than or equal to ohms. A high-frequency communication apparatus comprising the injection-locked oscillator according to claim 1.

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