JP2005204139A - Oscillation circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a transistor for constant current is inserted into a current path so that current value becomes fixed for suppressing frequency variation due to temperature variation, and thus, C/N deteriorates in the conventional oscillation circuit, in which current is shared by a buffer amplifier part and an oscillation part. <P>SOLUTION: The oscillation circuit is constituted so that the emitters of buffer amplifier transistors 23, 24 in a buffer amplifier part 2 are connected, a current is applied to an oscillation circuit core part 1 of the emitters via a buffer amplifier emitters resistor 50, a current-compensating resistor 52 and a current-compensating MOS transistor 53 are further connected in series with the emitters and connected to the ground. Then, when the current value of a buffer amplifier is varied by the temperature variation, since the potential of the emitters is raised, current for the portion of the rise in the potential by the current-compensating resistor 52 and the current-compensating MOS transistor 53 flows to the ground and is compensated so that the potential of collectors of oscillation transistors 3, 4 become constant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oscillation circuit for a high-frequency component.

  Conventional techniques will be described with reference to the drawings.

  6 is a circuit diagram of a conventional high-frequency buffer amplifier, FIG. 7 is a control diagram of oscillation frequency versus varicap voltage, and in FIG. 6, 1 is an oscillation circuit core section, 2 is a buffer amplifier section, and 3 and 4 are oscillation transistors. 5, 6 are oscillation feedback capacitors, 7, 8, 14, 15, 25, 26, 27, 28 are bias resistors, 9 is an oscillation circuit emitter resistor, 10, 11 are varicap coupling capacitors, and 12, 13 are varicaps. 16, 17 are MOS transistor capacitors, 18, 19 are resonant inductors, 20 is a buffer constant current transistor, 21 and 22 are oscillation circuit-buffer amplifier coupling capacitors, 23 and 24 are buffer amplifier transistors, 29 and 30 are output terminals, Reference numerals 31, 32, 33, and 34 denote voltage application terminals. In FIG. 7, reference numerals 101 and 102 denote MOS transistor capacitance switching frequencies.

  The oscillation circuit core unit 1 includes oscillation transistors 3 and 4, oscillation feedback capacitors 5 and 6, varicap coupling capacitors 10 and 11, varicaps 12 and 13, MOS transistor capacitors 16 and 17, and resonant inductors 18 and 19. Resonant circuit is included. The buffer amplifier unit 2 and the resonance circuit core unit 1 are connected by a buffer constant current transistor 20.

  An oscillation signal is generated by the oscillation circuit core unit 1, and the signal is input to the buffer amplifier transistors 23 and 24 via the oscillation circuit-buffer amplifier coupling capacitors 21 and 22, and a high-frequency oscillation signal is obtained from the output terminals 29 and 30. It is done.

  Further, as shown by lines 101 and 102 in FIG. 7, the oscillation frequency is continuously changed by continuously changing the control voltage of the control voltage application terminal 32 of the varicaps 12 and 13.

Furthermore, the oscillation frequency can be switched to either the frequency band of the line 101 or the line 102 by switching the voltage of the voltage application terminal 33 between the MOS transistor capacitors 16 and 17 to HIGH or LOW.
JP 2002-190709 A

  In the configuration as described above, by inserting a buffer constant current transistor between the buffer amplifier unit and the oscillation circuit core unit, the current value flowing through the buffer amplifier unit and the oscillation circuit core unit is made constant, and the buffer amplifier unit due to temperature fluctuations In addition, the value of the current flowing through the oscillation circuit core portion changes and the collector potential of the oscillation transistor varies, so that the difference voltage at both ends of the MOS transistor capacitance varies and the frequency variation can be suppressed. However, it has a problem that C / N is extremely deteriorated.

  An object of the present invention is to provide an oscillation circuit that realizes suppression of C / N deterioration and suppression of frequency fluctuation due to temperature fluctuation in an oscillation circuit in which the current of the buffer amplifier section and the oscillation circuit section is shared. To do.

  In order to achieve the above object, the present invention is such that a connection between the buffer amplifier unit and the oscillation circuit core unit is a resistance connection, and a variable resistor controlled by a temperature variation control circuit is connected to the ground in parallel with the connection. With this configuration, it is possible to obtain an oscillation circuit in which C / N is not deteriorated and frequency fluctuation due to temperature fluctuation is suppressed.

  According to the present invention, a variable resistor is connected to the ground in parallel with the emitter resistor of the buffer amplifier, and the collector potential of the oscillation transistor is controlled by controlling the buffer amplifier current even when the current value changes due to temperature fluctuation. It is possible to obtain a high-frequency oscillation circuit that is kept constant, has no C / N degradation, and has no frequency fluctuation due to temperature fluctuation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a circuit diagram of a high-frequency oscillation circuit according to a first embodiment of the present invention, in which 1 is an oscillation circuit core section, 2 is a buffer amplifier section, 3 and 4 are oscillation transistors, 5 and 6 are oscillation feedback capacitors, 7, 8, 14, 15, 25, 26, 27, 28 are bias resistors, 9 is an oscillation circuit emitter resistor, 10, 11 are varicap coupling capacitors, 12, 13 are varicaps, 16, 17 are MOS transistor capacitors, 18 and 19 are resonant inductors, 21 and 22 are oscillation circuit-buffer amplifier coupling capacitors, 23 and 24 are buffer amplifier transistors, 29 and 30 are output terminals, 31, 32, 33 and 34 are voltage application terminals, and 50 is a buffer amplifier. The emitter resistor, 52 is a current compensation resistor, and 53 is a current compensation MOS transistor.

  The emitters of the oscillation transistors 3 and 4 are connected to each other, and are connected to the ground via the emitter resistor 9. The bases of the oscillation transistors 3 and 4 are connected to the voltage application terminal 31 via the bias resistors 7 and 8. The oscillation signal is fed back from the collectors of the oscillation transistors 3 and 4 to the bases of the pair of oscillation transistors 3 and 4 via the oscillation feedback capacitors 5 and 6.

  The resonance circuit is formed between the collectors of the oscillation transistors 3 and 4, and the varicap coupling capacitors 10 and 11, the varicaps 12 and 13 as the capacitive elements, the MOS transistor capacitors 16 and 17, and the inductance element. The resonance frequency is determined by the resonance frequency of the capacitive element and the inductance element.

  The varicaps 12 and 13 for continuously changing the frequency are connected to the varicaps 12 and 13 through the varicap coupling capacitors 10 and 11 from the collectors of the oscillation transistors 3 and 4. The bias of the varicaps 12 and 13 is applied from the voltage application terminal 32 via the bias resistors 14 and 15. It is possible to continuously change the oscillation frequency by continuously controlling the voltage from the voltage application terminal 32.

  The MOS transistor capacitors 16 and 17 have one end connected to the collector of the oscillation transistors 3 and 4 and the other end connected to the voltage application terminal 33, and the frequency is switched to discrete by setting the voltage to HIGH or LOW from the voltage application terminal 33. It is possible.

  A signal oscillated from the oscillation circuit core unit 1 is input to the buffer amplifier transistors 23 and 24 via the oscillation circuit-buffer amplifier coupling capacitors 21 and 22 and output from the output terminals 29 and 30.

  The current from the buffer amplifier unit 2 is injected into the oscillation circuit core unit 1 through the buffer amplifier emitter resistor 50. A part of the emitter current of the buffer amplifier unit 2 is caused to flow to the ground via the current compensation resistor 52 and the current compensation MOS transistor 53. When the current value of the buffer amplifier fluctuates due to temperature fluctuation, the emitter potential of the buffer amplifier transistors 23 and 24 rises, so that the current increased by the current compensation resistor 52 and the current compensation MOS transistor 53 becomes the ground. The current is compensated so that the collector potential of the oscillation transistors 3 and 4 is constant.

  According to the above configuration, it is possible to obtain a high-frequency oscillation circuit that has no C / N degradation even in the case of a circuit configuration in which the current of the buffer amplifier and the oscillation circuit core is common, and that does not vary in oscillation frequency even when the temperature varies. It is.

  The elements 10, 11, 12, and 13 may be capacitive as a whole.

(Embodiment 2)
FIG. 2 is a circuit diagram of a high-frequency oscillation circuit according to the second embodiment of the present invention, in which 1 is an oscillation circuit core unit, 2 is a buffer amplifier unit, 3 and 4 are oscillation transistors, 5 and 6 are oscillation feedback capacitors, 7, 8, 14, 15, 25, 26, 27, 28 are bias resistors, 9 is an oscillation circuit emitter resistor, 10, 11 are varicap coupling capacitors, 12, 13 are varicaps, 16, 17 are MOS transistor capacitors, 18 and 19 are resonant inductors, 21 and 22 are oscillation circuit-buffer amplifier coupling capacitors, 23 and 24 are buffer amplifier transistors, 29 and 30 are output terminals, 31, 32, 33 and 34 are voltage application terminals, and 50 is a buffer amplifier. Emitter resistors 52 and 54 are current compensating resistors, and 53 and 55 are current compensating MOS transistors.

  The emitters of the oscillation transistors 3 and 4 are connected to each other and connected to the ground via the emitter resistor 9. The bases of the oscillation transistors 3 and 4 are connected to the voltage application terminal 31 via the bias resistors 7 and 8. . The oscillation signal is fed back from the collectors of the oscillation transistors 3 and 4 to the bases of the pair of oscillation transistors 3 and 4 via the oscillation feedback capacitors 5 and 6.

  The resonance circuit is formed between the collectors of the oscillation transistors 3 and 4, and the varicap coupling capacitors 10 and 11, the varicaps 12 and 13 as the capacitive elements, the MOS transistor capacitors 16 and 17, and the inductance element. The resonance frequency is determined by the resonance frequency of the capacitive element and the inductance element.

  The varicaps 12 and 13 for continuously changing the frequency are connected to the varicaps 12 and 13 through the varicap coupling capacitors 10 and 11 from the collectors of the oscillation transistors 3 and 4. The bias of the varicaps 12 and 13 is applied from the voltage application terminal 32 via the bias resistors 14 and 15. It is possible to continuously change the oscillation frequency by continuously controlling the voltage from the voltage application terminal 32.

  The MOS transistor capacitors 16 and 17 have one end connected to the collector of the oscillation transistors 3 and 4 and the other end connected to the voltage application terminal 33, and the frequency is switched to discrete by setting the voltage to HIGH or LOW from the voltage application terminal 33. It is possible.

  A signal oscillated from the oscillation circuit core unit 1 is input to the buffer amplifier transistors 23 and 24 via the oscillation circuit-buffer amplifier coupling capacitors 21 and 22 and output from the output terminals 29 and 30.

  The current from the buffer amplifier unit 2 is injected into the oscillation circuit core unit 1 through the buffer amplifier emitter resistor 50. A part of the base current of the buffer amplifier transistors 23 and 24 flows to the ground via the current compensation resistors 52 and 54 and the current compensation MOS transistors 53 and 55. When the base potential of the buffer amplifier transistors 23 and 24 rises due to temperature fluctuation and the current value fluctuates, the base current corresponding to the rise in potential by the current compensation resistors 52 and 54 and the current compensation MOS transistors 53 and 55 is obtained. The current flows to the ground, the emitter currents of the buffer amplifier transistors 23 and 24 are controlled, and the collector potential of the oscillation transistors 3 and 4 is compensated to be constant.

  According to the above configuration, it is possible to obtain a high-frequency oscillation circuit that has no C / N degradation even in the case of a circuit configuration in which the current of the buffer amplifier and the oscillation circuit core is common, and that does not vary in oscillation frequency even when the temperature varies. It is.

  The elements 10, 11, 12, and 13 may be capacitive as a whole.

(Embodiment 3)
FIG. 1 is a circuit diagram of a high-frequency oscillation circuit according to a third embodiment of the present invention, in which 1 is an oscillation circuit core section, 2 is a buffer amplifier section, 3 and 4 are oscillation transistors, 5 and 6 are oscillation feedback capacitors, 7, 8, 14, 15, 25, 26, 27, 28 are bias resistors, 9 is an oscillation circuit emitter resistor, 10, 11 are varicap coupling capacitors, 12, 13 are varicaps, 16, 17 are MOS transistor capacitors, 18 and 19 are resonant inductors, 21 and 22 are oscillation circuit-buffer amplifier coupling capacitors, 23 and 24 are buffer amplifier transistors, 29 and 30 are output terminals, 31, 32, 33 and 34 are voltage application terminals, and 50 is a buffer amplifier. An emitter resistor, 51 is a variable resistor for current compensation, 60 is a variable resistor control circuit, and 70 is a data memory for temperature compensation.

  The emitters of the oscillation transistors 3 and 4 are connected to each other and connected to the ground via the emitter resistor 9. The bases of the oscillation transistors 3 and 4 are connected to the voltage application terminal 31 via the bias resistors 7 and 8. . The oscillation signal is fed back from the collectors of the oscillation transistors 3 and 4 to the bases of the pair of oscillation transistors 3 and 4 via the oscillation feedback capacitors 5 and 6.

  The resonance circuit is formed between the collectors of the oscillation transistors 3 and 4, and the varicap coupling capacitors 10 and 11, the varicaps 12 and 13 as the capacitive elements, the MOS transistor capacitors 16 and 17, and the inductance element. The resonance frequency is determined by the resonance frequency of the capacitive element and the inductance element.

  The varicaps 12 and 13 for continuously changing the frequency are connected to the varicaps 12 and 13 through the varicap coupling capacitors 10 and 11 from the collectors of the oscillation transistors 3 and 4. The bias of the varicaps 12 and 13 is applied from the voltage application terminal 32 via the bias resistors 14 and 15. It is possible to continuously change the oscillation frequency by continuously controlling the voltage from the voltage application terminal 32.

  The MOS transistor capacitors 16 and 17 have one end connected to the collector of the oscillation transistors 3 and 4 and the other end connected to the voltage application terminal 33, and the frequency is switched to discrete by setting the voltage to HIGH or LOW from the voltage application terminal 33. It is possible.

  A signal oscillated from the oscillation circuit core unit 1 is input to the buffer amplifier transistors 23 and 24 via the oscillation circuit-buffer amplifier coupling capacitors 21 and 22 and output from the output terminals 29 and 30.

  The current from the buffer amplifier unit 2 is injected into the oscillation circuit core unit 1 through the buffer amplifier emitter resistor 50. A part of the emitter currents of the buffer amplifier transistors 23 and 24 are supplied to the ground through the current compensating variable resistor 51. When the current values of the buffer amplifier transistors 23 and 24 fluctuate due to temperature fluctuations, the temperature compensation data memory 70 is referred to, the variable resistance control circuit 60 changes the current compensation variable resistor 51, and the buffer amplifier transistors 23 and 24 A current corresponding to the rise of the emitter potential flows to the ground, and compensation is made so that the potentials of the collectors of the oscillation transistors 3 and 4 become constant.

  According to the above configuration, it is possible to obtain a high-frequency oscillation circuit that has no C / N degradation even in the case of a circuit configuration in which the current of the buffer amplifier and the oscillation circuit core is common, and that does not vary in oscillation frequency even when the temperature varies. It is.

(Embodiment 4)
FIG. 4 is a circuit diagram of a high-frequency oscillation circuit according to the fourth embodiment of the present invention. 7, 8, 14, 15, 25, 26, 27, 28 are bias resistors, 9 is an oscillation circuit emitter resistor, 10, 11 are varicap coupling capacitors, 12, 13 are varicaps, 16, 17 are MOS transistor capacitors, 18 and 19 are resonant inductors, 21 and 22 are oscillation circuit-buffer amplifier coupling capacitors, 23 and 24 are buffer amplifier transistors, 29 and 30 are output terminals, 31, 32, 33, 34 and 64 are voltage application terminals, and 50 is Buffer amplifier emitter resistor, 52 is a current compensation resistor, 53 is a current compensation MOS transistor, 61 is an operational amplifier circuit, 62 is an operational amplifier feedback resistor, and 63 is an operational amplifier. Amplifier feedback capacity.

  The emitters of the oscillation transistors 3 and 4 are connected to each other and connected to the ground via the emitter resistor 9. The bases of the oscillation transistors 3 and 4 are connected to the voltage application terminal 31 via the bias resistors 7 and 8. . The oscillation signal is fed back from the collectors of the oscillation transistors 3 and 4 to the bases of the pair of oscillation transistors 3 and 4 via the oscillation feedback capacitors 5 and 6.

  The resonance circuit is formed between the collectors of the oscillation transistors 3 and 4, and the varicap coupling capacitors 10 and 11, the varicaps 12 and 13 as the capacitive elements, the MOS transistor capacitors 16 and 17, and the inductance element. The resonance frequency is determined by the resonance frequency of the capacitive element and the inductance element.

  The varicaps 12 and 13 for continuously changing the frequency are connected to the varicaps 12 and 13 through the varicap coupling capacitors 10 and 11 from the collectors of the oscillation transistors 3 and 4. The bias of the varicaps 12 and 13 is applied from the voltage application terminal 32 via the bias resistors 14 and 15. It is possible to continuously change the oscillation frequency by continuously controlling the voltage from the voltage application terminal 32.

  The MOS transistor capacitors 16 and 17 have one end connected to the collector of the oscillation transistors 3 and 4 and the other end connected to the voltage application terminal 33, and the frequency is switched to discrete by setting the voltage to HIGH or LOW from the voltage application terminal 33. It is possible.

  A signal oscillated from the oscillation circuit core unit 1 is input to the buffer amplifier transistors 23 and 24 via the oscillation circuit-buffer amplifier coupling capacitors 21 and 22 and output from the output terminals 29 and 30.

  The current from the buffer amplifier unit 2 is injected into the oscillation circuit core unit 1 through the buffer amplifier emitter resistor 50. Further, part of the emitter currents of the buffer amplifier transistors 23 and 24 flow to the ground via the current compensation resistor 52 and the current compensation MOS transistor 53. When the current value of the oscillation circuit emitter resistor 9 varies due to temperature variation, the emitter potential of the oscillation transistors 3 and 4 rises. The emitter potential is input to the operational amplifier circuit 61, the current compensation MOS transistor 53 is controlled by the operational amplifier feedback resistor 62 and the operational amplifier feedback capacitor 63, and a part of the emitter current of the buffer amplifier transistors 23 and 24 flows to the ground. 4 is compensated so that the potential of the collector 4 becomes constant.

  According to the above configuration, it is possible to obtain a high-frequency oscillation circuit that has no C / N degradation even in the case of a circuit configuration in which the current of the buffer amplifier and the oscillation circuit core is common, and that does not vary in oscillation frequency even when the temperature varies. It is.

  The elements 10, 11, 12, and 13 may be capacitive as a whole.

  Note that not only temperature fluctuations but also frequency fluctuations due to voltage fluctuations can be compensated.

(Embodiment 5)
FIG. 5 is a circuit diagram of a high-frequency oscillation circuit according to the fifth embodiment of the present invention. Reference numeral 1 denotes an oscillation circuit core unit, 2 denotes a buffer amplifier unit, 3 and 4 denote oscillation transistors, 5 and 6 denote oscillation feedback capacitors, 7, 8, 14, 15, 25, 26, 27, 28 are bias resistors, 9 is an oscillation circuit emitter resistor, 10, 11 are varicap coupling capacitors, 12, 13 are varicaps, 16, 17 are MOS transistor capacitors, 18 and 19 are resonant inductors, 21 and 22 are oscillation circuit-buffer amplifier coupling capacitors, 23 and 24 are buffer amplifier transistors, 29 and 30 are output terminals, 31, 32, 33, 34 and 64 are voltage application terminals, and 50 is Buffer amplifier emitter resistor, 52 and 54 are current compensation resistors, 53 and 55 are current compensation MOS transistors, 61 is an operational amplifier circuit, and 62 is an operational amplifier feedback resistor. 63 are operational amplifier feedback capacitors.

  The emitters of the oscillation transistors 3 and 4 are connected to each other and connected to the ground via the emitter resistor 9. The bases of the oscillation transistors 3 and 4 are connected to the voltage application terminal 31 via the bias resistors 7 and 8. . The oscillation signal is fed back from the collectors of the oscillation transistors 3 and 4 to the bases of the pair of oscillation transistors 3 and 4 via the oscillation feedback capacitors 5 and 6.

  The resonance circuit is formed between the collectors of the oscillation transistors 3 and 4, and the varicap coupling capacitors 10 and 11, the varicaps 12 and 13 as the capacitive elements, the MOS transistor capacitors 16 and 17, and the inductance element. The resonance frequency is determined by the resonance frequency of the capacitive element and the inductance element.

  The varicaps 12 and 13 for continuously changing the frequency are connected to the varicaps 12 and 13 through the varicap coupling capacitors 10 and 11 from the collectors of the oscillation transistors 3 and 4. The bias of the varicaps 12 and 13 is applied from the voltage application terminal 32 via the bias resistors 14 and 15. It is possible to continuously change the oscillation frequency by continuously controlling the voltage from the voltage application terminal 32.

  The MOS transistor capacitors 16 and 17 have one end connected to the collector of the oscillation transistors 3 and 4 and the other end connected to the voltage application terminal 33, and the frequency is switched to discrete by setting the voltage to HIGH or LOW from the voltage application terminal 33. It is possible.

  A signal oscillated from the oscillation circuit core unit 1 is input to the buffer amplifier transistors 23 and 24 via the oscillation circuit-buffer amplifier coupling capacitors 21 and 22 and output from the output terminals 29 and 30.

  The current from the buffer amplifier unit 2 is injected into the oscillation circuit core unit 1 through the buffer amplifier emitter resistor 50. A part of the base current of the buffer amplifier transistors 23 and 24 flows to the ground via the current compensation resistors 52 and 54 and the current compensation MOS transistors 53 and 55. When the current value of the oscillation circuit emitter resistor 9 varies due to temperature variation, the emitter potential of the oscillation transistors 3 and 4 rises. The emitter potential is input to the operational amplifier circuit 61, and the current compensation MOS transistors 53 and 55 are controlled by the operational amplifier feedback resistor 62 and the operational amplifier feedback capacitor 63 so that part of the base current of the buffer amplifier transistors 23 and 24 flows to the ground. The emitter currents of the transistors 23 and 24 are controlled, and compensation is performed so that the collector potentials of the oscillation transistors 3 and 4 become constant.

  According to the above configuration, it is possible to obtain a high-frequency oscillation circuit that has no C / N degradation even in the case of a circuit configuration in which the current of the buffer amplifier and the oscillation circuit core is common, and that does not vary in oscillation frequency even when the temperature varies. It is.

  The elements 10, 11, 12, and 13 may be capacitive as a whole.

  Note that not only temperature fluctuations but also frequency fluctuations due to voltage fluctuations can be compensated.

  As described above, the present invention is effective in constructing a temperature compensated oscillation circuit having a small frequency drift with respect to temperature fluctuations and no C / N deterioration.

1 is a circuit diagram of a high-frequency oscillation circuit according to a first embodiment of the present invention. Circuit diagram of high-frequency oscillation circuit in second embodiment of the present invention Circuit diagram of high-frequency oscillation circuit in third embodiment of the present invention Circuit diagram of high-frequency oscillation circuit in fourth embodiment of the present invention Circuit diagram of high-frequency oscillation circuit in fifth embodiment of the present invention Circuit diagram of conventional high-frequency buffer amplifier Oscillation frequency vs. varicap voltage control diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oscillation circuit core part 2 Buffer amplifier part 3, 4 Oscillation transistor 5, 6 Oscillation feedback capacity 7, 8, 14, 15, 25, 26, 27, 28 Bias resistance 9 Oscillation circuit emitter resistance 10, 11 Varicap coupling capacity 12 , 13 Varicaps 16, 17 MOS transistor capacitors 18, 19 Resonant inductors 21, 22 Oscillator circuit-buffer amplifier coupling capacitors 23, 24 Buffer amplifier transistors 29, 30 Output terminals 31, 32, 33, 34, 64 Voltage application terminal 50 Buffer Amplifier emitter resistor 52 Current compensation resistor 53 Current compensation MOS transistor 61 Operational amplifier circuit 62 Operational amplifier feedback resistor 63 Operational amplifier feedback capacitance

Claims (5)

A differential amplifier composed of first and second transistors;
It is composed of first and second inductances that share a current, third and fourth transistors for oscillation, and first and second MOS varactors, and oscillates by inputting current from the differential amplifier. An oscillation circuit;
An oscillation circuit comprising: a variable resistor that causes a part of the current of the differential amplifier to flow to ground in order to maintain the voltage applied to the oscillation circuit. A differential amplifier composed of first and second transistors;
It is composed of first and second inductances that share a current, third and fourth transistors for oscillation, and first and second MOS varactors, and oscillates by inputting current from the differential amplifier. An oscillation circuit;
A variable resistor that allows a part of the current of the differential amplifier to flow to ground,
An oscillation circuit comprising a variable resistance control circuit that controls the variable resistance in order to maintain an applied voltage of the oscillation circuit.   3. The oscillation circuit according to claim 1, wherein the variable resistor is connected to an emitter of the differential amplifier.   The oscillation circuit according to claim 1, wherein the variable resistor is connected to a base of the differential amplifier. A differential amplifier composed of first and second transistors;
It is composed of first and second inductances that share a current, third and fourth transistors for oscillation, and first and second MOS varactors, and oscillates by inputting current from the differential amplifier. An oscillation circuit;
A variable resistor that allows a part of the current of the differential amplifier to flow to ground,
A memory circuit in which the temperature correction coefficient is stored;
A variable resistance control circuit for controlling the variable resistance with reference to data of the memory circuit in order to maintain an applied voltage of the oscillation circuit;
An oscillation circuit comprising:

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