JP2007067647A - Voltage controlled oscillation circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage controlled oscillation circuit wherein a power supply system isolated from that of a buffer amplifier is connected to a constant voltage generating circuit and an output transistor of the constant voltage generating circuit is shared with a transistor of the buffer amplifier so as to suppress the effect of power noises without decreasing a voltage of the power supply and to be downsizd. <P>SOLUTION: The differential buffer amplifier 11 comprises bipolar transistors 24, 25 whose emitters are connected in common and load resistors 26, 27 connected to a point of a power supply voltage Vcc, and the commonly connected emitters are connected to a midpoint of an inductor of a differential oscillator 12. A grounding capacitor is also connected to the midpoint of the inductor of a differential oscillator 12 to suppress unnecessary interference and avoid a noise sneak path. Signals oscillated from the differential oscillator 12 are outputted from output terminals 13 of the differential buffer amplifier 11 via coupling capacitors 21, 22. Bases of the bipolar transistors 24, 25 are connected to the constant voltage generating circuit 61 via resistors 28, 29 so as to apply a bias voltage to the circuit 61 through the isolation from the power supply system of the circuit 61. Thus, the adverse effect of power noises is suppressed, outputs are obtained without decreasing the power supply voltage, the current consumption is suppressed, and the adverse effect of the power noises is suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an oscillation circuit that can reduce the influence of power supply ripple while realizing low consumption in an oscillation circuit integrated in a semiconductor, and can realize low consumption, and an oscillator that can share current with the buffer amplifier of the oscillation circuit And a voltage controlled oscillation circuit in which a buffer amplifier and a constant voltage generation circuit are partly configured in common.

  In recent years, semiconductor oscillators used in portable devices are required to have high C / N, low current consumption, and downsizing. Of these, low power consumption is natural, and it is necessary for semiconductors that are resistant to the effects of power supply noise to meet various sets of power supply ripple specifications and to achieve high-performance oscillator C / N (carrier-to-noise ratio). Has been.

  In the general PLL shown in FIG. 8, the oscillator appears as phase noise degradation of fout due to noise wraparound from the power supply voltage. In particular, low frequency power supply noise from the power supply system cannot be reduced by the PLL loop filter and is output as it is to fout, which is a problem.

  FIG. 9 shows an oscillation circuit well known as a circuit for operating the oscillator main body and the buffer amplifier with a common current. In FIG. 9, 45 is a Colpitts oscillator having a common collector, 44 is a buffer amplifier having a common emitter, 43 is an output terminal, 46 is a coupling capacitor, and 47 is a grounding capacitor.

  The Colpitts oscillator 45 is a Colpitts oscillation circuit in which a capacitor 49 is connected between the base and emitter of the bipolar transistor 48, a capacitor 50 is connected between the emitter and collector, and a capacitor 51 and an inductor 52 are combined between the base and collector. 48 collectors are grounded by a grounding capacitor 47. The buffer amplifier 44 is a grounded-emitter amplifier in which the emitter of the bipolar transistor 53 is grounded by a grounding capacitor 47 and the inductor 54 is used as a load.

  The oscillation signal is input from the Colpitts oscillator 45 to the buffer amplifier 44 through the coupling capacitor 46 and output from the output terminal 43. A common operating current flows through the bipolar transistors 48 and 53 constituting the Colpitts oscillator 45 and the buffer amplifier 44. However, if power supply noise is generated in the power supply voltage Vcc of FIG. 9, the base voltages of the bipolar transistors 53 and 48 directly fluctuate. Therefore, the influence of the power supply noise is caused by the collector grounded Colpitts oscillator 45 and the emitter grounded buffer amplifier 44. As a result, the oscillating frequency of the collector-grounded Colpitts oscillator 45 is also directly affected by power supply noise.

  Since the Colpitts oscillator described above has a single-phase output operation, it is sensitive to noise transmitted through the power supply and the substrate and has a disadvantage that the oscillation operation tends to become unstable. As a configuration for solving these problems, a differential oscillator as shown in FIG. 10 is generally used.

  FIG. 10 shows a differential oscillator including a pair of field effect transistors. In FIG. 10, reference numeral 12 denotes a differential oscillator, which includes a resonator 14 configured by connecting drains and gates of field effect transistors 18 and 19 to each other, and connecting an inductor 16 and a capacitor 17 in parallel. The differential oscillation circuit is connected to the drains of the field effect transistors 18 and 19. The sources of the field effect transistors 18 and 19 are connected to the drain of the field effect transistor 20, and the current flowing through the differential oscillator 12 is determined by biasing the gate of the field effect transistor 20 through the bias terminal 15.

  However, when a power supply voltage Vcc is applied to the midpoint of the inductor 16 as shown in FIG. 10 and power supply noise occurs in the power supply voltage Vcc, the inductor 16 is similarly affected by power supply noise such as C / N deterioration of the oscillator. Like the single-phase output oscillator (Colpitts-type oscillator), it is affected by power supply noise. Further, the oscillator using the differential circuit as shown in FIG. 10 does not include a buffer amplifier, and there is a problem that a separate buffer amplifier is required and the current consumption increases.

  Further, as a countermeasure against power supply noise, as shown in FIGS. 11, 12, 13, and 14, a constant voltage generation circuit and a filter circuit for reducing the influence on the power supply noise in the oscillation circuit are required.

  The filter circuit 62 shown in FIGS. 11 and 13 can prevent high-frequency component noise superimposed on the power supply voltage Vcc from being transmitted by the low-pass filter having the ground capacitor 64 and the resistor 63 coupled in series with the power supply. . The general constant voltage generation circuit 61 shown in FIGS. 12 and 14 is composed of a band gap circuit and an operational amplifier circuit (not shown). Similarly, by inserting them in series with the power supply voltage Vcc, it is possible to prevent the transmission of high-frequency component noise.

  However, in the filter circuit 62 described above, when the resistance value of the resistor 63 increases, the power supply voltage Vcc decreases. Therefore, in order to increase the cutoff frequency, it is necessary to increase the value of the ground capacitance 64. In this case, however, there arises a problem that the mask area is increased and the layout design is restricted. Furthermore, in order to sufficiently suppress noise, there is a problem that the lock-up time, which is a characteristic of the PLL, is delayed depending on the CR time constant. Further, even when the constant voltage generating circuit 61 is inserted in series, there is a problem that the power supply voltage Vcc is lowered and the amplitude is lowered.

  Patent Document 1 describes that a differential buffer amplifier including a differential oscillator functions with a common operating current. As shown in FIG. 15, in addition to the differential oscillator 12 shown in FIG. 10, the differential buffer amplifier 11 includes bipolar transistors 24 and 25 having common emitters and load resistors 26 and 27. The load resistors 26 and 27 are connected to the power supply voltage Vcc.

  The common emitters of the bipolar transistors 24 and 25 are connected to the midpoint of the inductor 16, and thus the differential buffer amplifier 11 and the differential oscillator 12 are connected in series to the power supply voltage Vcc. The operating current of the oscillator 12 is supplied from the midpoint of the inductor 16, and this operating current also acts as a tail current of the differential buffer amplifier 11.

  In addition, a ground capacitor 23 is connected to the midpoint of the inductor 16 to suppress unnecessary interference between the differential oscillator 12 and the differential buffer amplifier 11 and to suppress noise from entering the inductor 16. The oscillation signal is input to the differential buffer amplifier 11 via the coupling capacitors 21 and 22, and a signal is taken out from the output terminal 13.

  According to this configuration, since the differential oscillator 12 and the differential buffer amplifier 11 have the same operating current, the current consumption can be greatly reduced as compared with the case where they are driven separately. The resistance to external noise is also high, and the oscillation operation does not become unstable due to the noise, and the noise added to the connection between the differential buffer amplifier 11 and the node of the inductor 16 is suppressed by the capacitor.

  In FIG. 16, as another differential oscillator 12, the collector and base of each of bipolar transistors 30 and 31 are cross-connected to each other via feedback capacitors 32 and 33, and an inductor 16 and a capacitor 17 are connected in parallel. A configuration is shown in which the device 14 is connected to the collector of each of the bipolar transistors 30 and 31. As shown in FIG. 16, in the bipolar transistor instead of the field effect transistor, the emitter is grounded by the resistor 36 and the base is biased from the bias terminal 15 via the resistors 34 and 35, so that it flows to the differential oscillator 59. Determine the current. Since the bipolar transistor is used, the current amplification factor gm is higher than that of the CMOS, so that oscillation can be started with a smaller current.

Patent Document 2 discloses a drive voltage generation in a voltage control oscillation circuit including a drive voltage generation circuit that outputs a drive voltage Vos according to a control voltage Vcn and a ring oscillator circuit that operates by receiving the supply of the drive voltage Vos. Generates a drive voltage Vos using a feedback circuit formed by an operational amplifier that operates upon receiving the supply of the power supply voltage Vdd, thereby suppressing the influence of high frequency components superimposed on the power supply voltage Vdd, that is, noise. Thus, it is described that the output clock CLKO with a small phase fluctuation is stably generated.
JP 2005-198084 A JP 2002-111449 A

  However, as a countermeasure against noise from a general power supply system in the configuration of Patent Document 1, in order to reduce the influence on power supply noise, the constant voltage generation circuit 61 and the filter circuit 62 shown in FIGS. 17 and 18 are provided. For example, as described above, in the filter circuit 62, when the resistance value of the resistor 63 increases, the power supply voltage decreases. Therefore, in order to increase the cut-off frequency, it is necessary to increase the value of the ground capacitance 64. In this case, however, a problem arises that the mask area is increased and the layout design is restricted. Furthermore, in order to sufficiently suppress noise, there is a problem that the lock-up time, which is a characteristic of the PLL, is delayed depending on the CR time constant. Further, as described above, when the constant voltage generating circuit 61 is inserted in series with the power supply voltage Vcc, there is a problem that the voltage is lowered and the amplitude is lowered.

  The present invention is directed to solving the above-described problems of the prior art, suppresses the influence of power supply noise, and cascode-connects a differential oscillator and a differential buffer amplifier so that they function with a common operating current. In order to reduce the influence on the power supply noise in the dynamic oscillation circuit, it is composed of a differential or Colpitts type oscillator, a buffer amplifier cascode-connected to this oscillator, and a constant voltage generation circuit, and is connected to the buffer amplifier. The power supply system is separated and connected to the output of the constant voltage generation circuit, and by sharing a part, the influence of the power supply noise is suppressed without lowering the power supply voltage Vcc, and the restriction on the mask area is eliminated. An object of the present invention is to provide a voltage controlled oscillation circuit.

  In order to achieve the above object, a voltage controlled oscillation circuit according to claim 1 of the present invention includes an oscillator, a buffer amplifier cascode-connected to the oscillator, and a constant voltage generation circuit, and is connected to the buffer amplifier. The power supply system is separated and connected to the output of the constant voltage generation circuit.

  The voltage controlled oscillation circuit according to claim 2 is the voltage controlled oscillation circuit according to claim 1, wherein the oscillator includes a resonator having a midpoint of the inductor as a node and an operating current is supplied from the midpoint of the inductor. A differential buffer amplifier having a transistor pair that is cascode-connected to the differential oscillator and operates using the operating current as a tail current, the output of the differential oscillator being input to the differential buffer amplifier The power supply system is separated by connecting the base bias of the differential buffer amplifier to the output of the constant voltage generation circuit.

  Further, in the voltage controlled oscillation circuit according to any one of claims 3 to 5, in the voltage controlled oscillation circuit according to claims 1 and 2, an oscillator connects a resonator between drains of a pair of field effect transistors having sources connected in common. And having one drain cross-connected to the other gate, or connecting a resonator between the collectors of a pair of bipolar transistors having a common emitter connected, and one collector cross-connected to the other base, Alternatively, it is a Colpitts type oscillator having a grounded base or a grounded gate.

  According to a sixth aspect of the present invention, there is provided the voltage controlled oscillator circuit according to the first aspect, wherein the oscillator is a single-phase output oscillator.

  According to a seventh aspect of the present invention, there is provided a voltage controlled oscillation circuit including an oscillator, a buffer amplifier cascode-connected to the oscillator, and a constant voltage generation circuit, and separating a power supply system connected to the buffer amplifier. The output transistor of the constant voltage generation circuit and the transistor of the buffer amplifier are shared by connecting to the output.

  The voltage-controlled oscillation circuit according to claim 8 is the voltage-controlled oscillation circuit according to claim 7, wherein the oscillator includes a resonator having a midpoint of the inductor as a node and an operating current is supplied from the midpoint of the inductor. A differential buffer amplifier having a transistor pair that is cascode-connected to the differential oscillator and operates using the operating current as a tail current, the output of the differential oscillator being input to the differential buffer amplifier The base bias of the differential buffer amplifier is connected to the output of the constant voltage generation circuit to separate the power supply system, and the transistor of the output of the constant voltage generation circuit and the transistor pair of the differential buffer amplifier are shared .

  The voltage controlled oscillation circuit according to claims 9 to 11 is the voltage controlled oscillation circuit according to claims 7 and 8, wherein the oscillator connects a resonator between the drains of the pair of field effect transistors having the sources connected in common. And having one drain cross-connected to the other gate, or connecting a resonator between the collectors of a pair of bipolar transistors having a common emitter connected, and one collector cross-connected to the other base, Alternatively, it is a Colpitts type oscillator having a grounded base or a grounded gate.

  According to a twelfth aspect of the present invention, there is provided the voltage controlled oscillation circuit according to the seventh aspect, wherein the oscillator is a single-phase output oscillator.

  According to the above configuration, the oscillator and the buffer amplifier function with a common operating current, and the power supply system of the buffer amplifier is separated to reduce the influence of the overall current consumption and power supply noise. By sharing a part of the generation circuit, it is possible to obtain a voltage-controlled oscillation circuit with low consumption and size.

  According to the present invention, a differential oscillator and a differential buffer amplifier using a differential circuit having high noise resistance are made to function with a common operating current to reduce the overall current consumption. Further, the buffer amplifier and the constant voltage generation circuit By sharing a part of the circuit, it is possible to configure a voltage-controlled oscillation circuit that is low in consumption and downsized.

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

  FIG. 1 is a diagram illustrating a voltage controlled oscillation circuit according to the first embodiment of the present invention. In FIG. 1, 11 is a differential buffer amplifier, 12 is a differential oscillator, and 61 is a constant voltage generating circuit.

  The differential oscillator 12 includes a field effect transistor 18, 19 having a resonator 14 in which the drain and gate of each of the field effect transistors 18, 19 are cross-connected to each other and the inductor 16 and the capacitor 17 are connected in parallel. It is a differential oscillation circuit type connected to each drain. The sources of the field effect transistors 18 and 19 are connected to the drain of the field effect transistor 20, and the current flowing through the differential oscillator 12 is determined by biasing the gate of the field effect transistor 20 through the bias terminal 15.

  The differential buffer amplifier 11 includes bipolar transistors 24 and 25 having common emitters and load resistors 26 and 27, and the load resistors 26 and 27 are connected to the power supply voltage Vcc. A common emitter of the bipolar transistors 24 and 25 is connected to the midpoint of the inductor 16. Thus, the differential buffer amplifier 11 and the differential oscillator 12 are connected in series to the power supply voltage Vcc, and the operating current of the differential oscillator 12 is supplied from the midpoint of the inductor 16 and this operation is performed. The current also acts as a tail current for the differential buffer amplifier 11.

  In addition, a ground capacitor 23 is connected to the midpoint of the inductor 16 and serves to suppress unnecessary interference between the differential oscillator 12 and the differential buffer amplifier 11 and to suppress noise from entering the inductor 16. The oscillation signal of the differential oscillator 12 is input to the differential buffer amplifier 11 through the coupling capacitors 21 and 22, and a signal is taken out from the output terminal 13.

  FIG. 2 is a diagram showing a constant voltage generation circuit of the voltage controlled oscillation circuit according to the first embodiment. As shown in FIG. 2, the bases of the bipolar transistors 24 and 25 of the differential buffer amplifier 11 are connected to the output of the low-saturation constant voltage generation circuit 61 through resistors 28 and 29 and supplied with a bias voltage. Yes. The low-saturation constant voltage generation circuit 61 includes a general band gap regulator 69 and an operational amplifier 60. The output of the operational amplifier 60 is connected to the base of an NPN bipolar transistor 68 and fed back to the input via a collector.

  According to the first embodiment, the low-saturation constant voltage generation circuit 61 is connected to the differential buffer amplifier 11 to suppress the influence of power supply noise and is separated from the power supply system of the differential buffer amplifier 11. In addition, the amplitude can be output without reducing the power supply voltage Vcc of the differential buffer amplifier 11. Thereby, the effect of suppressing the influence of power supply noise can be obtained without increasing the current consumption by not reducing the amplitude of the differential buffer amplifier 11.

  FIG. 3 is a diagram showing a voltage controlled oscillation circuit according to the second embodiment of the present invention. As shown in FIG. 3, in the differential oscillator 59, the collectors and bases of the bipolar transistors 30 and 31 are cross-connected to each other via feedback capacitors 32 and 33, and the inductor 16 and the capacitor 17 are connected in parallel. This is a differential oscillation circuit type in which the resonator 14 configured as described above is connected to the collectors of the bipolar transistors 30 and 31.

  In the bipolar transistors 30 and 31, the emitter is grounded via the resistor 36 and the base is biased from the bias terminal 15 via the resistors 34 and 35, whereby the current flowing through the differential oscillator 59 is determined. The configuration other than the differential oscillator 59 is the same as that of the first embodiment of the invention shown in FIG.

  According to the second embodiment, in addition to the effects of the first embodiment, since the differential oscillator 59 is composed of the bipolar transistors 30 and 31, the current amplification factor gm is higher than that of the CMOS. It also has the feature of starting oscillation.

  Further, as shown in FIG. 4, the differential oscillator 12 may be a grounded Colpitts oscillator. Capacitors 37 and 38 are connected between the collectors and emitters of the bipolar transistors 30 and 31, and a capacitor 39 is connected between the emitters. A resonator 14 in which the inductor 16 and the capacitor 17 are connected in parallel is connected to the bipolar transistors 30 and 31. It is a differential oscillation circuit type connected to each collector. The bipolar transistors 30 and 31 have their emitters grounded by resistors 40 and 41, and the base is biased from the bias terminal 15, whereby the current flowing through the differential oscillator 12 is determined. The bias terminal 15 is grounded by a grounding capacitor 42.

  Also in this configuration, as in the first embodiment, the low-saturation constant voltage generation circuit 61 is connected to the differential buffer amplifier 11 to suppress the influence of power supply noise and separated from the power supply system of the differential buffer amplifier 11. Therefore, the amplitude can be output without lowering the power supply voltage Vcc of the differential buffer amplifier 11, the current consumption is not increased by not lowering the amplitude of the differential buffer amplifier 11, and the influence of power supply noise is affected. The effect of suppressing is acquired. The differential oscillator 12 has been described with reference to a grounded Colpitts oscillator as an example, but a grounded Colpitts oscillator may be used.

  FIG. 5 is a diagram showing a voltage controlled oscillation circuit according to the third embodiment of the present invention. In the third embodiment, one of the paired bipolar transistors 24 and 25 in the differential buffer amplifier 11 is shared by the bipolar transistor 68 that is the output transistor of the constant voltage generating circuit 61 shown in FIG. As shown in FIG. 5, the bipolar transistors 65 and 66 of the differential buffer amplifier 11a are configured. Other configurations are the same as those of the first embodiment shown in FIG.

  According to the third embodiment, the circuit is simplified by sharing the differential buffer amplifier 11a and the output transistor of the constant voltage generation circuit 61, and the power source of the differential buffer amplifier 11a is explained as described in the first embodiment. Since it is separated from the system, it has the feature that the amplitude can be output without lowering the power supply voltage Vcc of the differential buffer amplifier 11a. As in the second embodiment, a bipolar transistor may be used instead of the field effect transistor as the differential oscillator.

  Thereby, there is an effect of suppressing the influence of the power supply noise without increasing the current consumption by not reducing the amplitude of the differential buffer amplifier 11a, which is equivalent to the first embodiment and simplified by sharing the circuit. This can contribute to reduction of the mask area.

  FIG. 6 is a diagram showing a voltage controlled oscillation circuit according to the fourth embodiment of the present invention. In FIG. 6, 44 is a grounded-emitter buffer amplifier, 45 is a collector-grounded Colpitts oscillator, 43 is an output terminal, 46 is a coupling capacitor, and 47 is a grounded capacitor.

  As shown in FIG. 6, the Colpitts oscillator 45 is a Colpitts oscillator 45 in which a capacitor 49 is connected between the base and emitter of the bipolar transistor 48, a capacitor 50 is connected between the emitter and collector, and a capacitor 51 and an inductor 52 are combined between the base and collector. This is an oscillation circuit, and has a collector grounding type in which the collector of the bipolar transistor 48 is grounded by a grounding capacitor 47.

  The buffer amplifier 44 is a grounded-emitter amplifier in which the emitter of the bipolar transistor 53 is grounded by a grounded capacitor 47 and the inductor 54 is used as a load. The base bias of the bipolar transistor 53 of the grounded-emitter buffer amplifier 44 is connected to the output of the constant voltage generation circuit 61. As a result, the low saturation constant voltage generation circuit 61 equivalent to that of the first embodiment is connected to the buffer amplifier 44 to suppress the influence of power supply noise and is separated from the power supply system of the buffer amplifier 44. The amplitude can be output without lowering the power supply voltage Vcc of 44, and thereby the effect of suppressing the influence of power supply noise can be obtained without increasing the current consumption by not reducing the amplitude of the buffer amplifier 44. .

  FIG. 7 is a diagram showing a voltage controlled oscillation circuit according to the fifth embodiment of the present invention. In the fifth embodiment, the bipolar transistor 68 that is the output transistor of the constant voltage generation circuit 61 shown in FIG. 6 and the bipolar transistor 53 of the buffer amplifier 44 are shared. As shown in FIG. 7, it is configured in common with the bipolar transistor 67 of the buffer amplifier 44a. Other configurations are the same as those of the fourth embodiment shown in FIG.

  According to the fifth embodiment, the circuit is simplified by sharing the output transistor of the buffer amplifier 44a and the constant voltage generation circuit 61, and as described in the fourth embodiment, the buffer amplifier 44a is separated from the power supply system. Therefore, it has the feature that the amplitude can be output without lowering the power supply voltage Vcc of the buffer amplifier 44a. As a result, it is possible to contribute to the reduction of the mask area by simplification by sharing the circuit equivalent to the third embodiment.

  The voltage controlled oscillation circuit according to the present invention reduces the overall current consumption by causing a differential oscillator and a differential buffer amplifier using a differential circuit with high noise tolerance to function with a common operating current, By sharing a part of the constant voltage generation circuit, it is possible to configure a voltage-controlled oscillation circuit that is low in consumption and miniaturized, and can reduce the influence of power supply ripple while realizing low consumption and achieve low consumption. This is useful for an oscillation circuit of a portable device.

The figure which shows the CMOS type voltage control oscillation circuit in Embodiment 1 of this invention The figure which showed the constant voltage generation circuit of the voltage controlled oscillation circuit in this Embodiment 1. The figure which shows the bipolar type voltage controlled oscillation circuit in Embodiment 2 of this invention The figure which shows the Colpitts type voltage control oscillation circuit in this Embodiment 2. The figure which shows the voltage control oscillation circuit which shared a part in Embodiment 3 of this invention The figure which shows the voltage-controlled oscillation circuit of the single phase output in Embodiment 4 of this invention The figure which shows the voltage-controlled oscillation circuit of the one-phase output which shared a part in Embodiment 5 of this invention Block diagram showing a general PLL circuit Circuit diagram showing a conventional buffer amplifier integrated oscillator circuit Circuit diagram showing a conventional differential oscillator Figure showing countermeasures against power supply ripple in a conventional buffer amplifier integrated oscillator circuit Figure showing countermeasures against power supply ripple in a conventional buffer amplifier integrated oscillator circuit Diagram showing countermeasures against power supply ripple in a conventional differential oscillation circuit Diagram showing countermeasures against power supply ripple in a conventional differential oscillation circuit Circuit diagram showing a conventional differential amplifier circuit (CMOS type) integrated with a buffer amplifier A circuit diagram showing a conventional differential oscillation circuit (bipolar type) integrated with a buffer amplifier Diagram showing power supply ripple countermeasures for a conventional differential oscillation circuit (CMOS type) integrated with a buffer amplifier Diagram showing countermeasures against power supply ripple in a conventional differential oscillation circuit with integrated buffer amplifier (bipolar type)

Explanation of symbols

11, 11a Differential buffer amplifier 12 Differential oscillator (CMOS type)
13, 43 Output terminal 14 Resonator 15 Bias terminal 16, 52, 54 Inductors 17, 37, 38, 39, 49, 50, 51 Capacitors 18, 19, 20 Field effect transistors 21, 22, 46 Coupling capacitors 23, 42, 47, 64 Ground capacitance 24, 25, 30, 31, 48, 53, 65, 66, 67, 68 Bipolar transistors 26, 27 Load resistors 28, 29, 34, 35, 36, 40, 41, 55, 56, 57 , 58, 63 Resistors 32, 33 Feedback capacitance 62 Filter circuits 44, 44a Buffer amplifier 45 Colpitts oscillator 59 Differential oscillator (bipolar type)
60 operational amplifier 61 constant voltage generation circuit 69 band gap regulator

Claims (12)

An oscillator, a buffer amplifier cascode-connected to the oscillator, and a constant voltage generation circuit,
A voltage controlled oscillation circuit characterized in that a power supply system connected to the buffer amplifier is separated and connected to an output of the constant voltage generation circuit. The oscillator includes a resonator having a midpoint of an inductor as a node, and an operating current is supplied from the midpoint of the inductor, and the buffer amplifier is cascode-connected to the differential oscillator, and the operating current A differential buffer amplifier having a transistor pair operating as a tail current,
The output of the differential oscillator is input to the differential buffer amplifier, and the power supply system is separated by connecting a base bias of the differential buffer amplifier to an output of a constant voltage generation circuit. Voltage controlled oscillator circuit.   3. The voltage control according to claim 1, wherein the oscillator has a resonator connected between drains of a pair of field effect transistors having sources connected in common, and one drain is cross-connected to the other gate. Oscillator circuit.   3. The voltage controlled oscillation according to claim 1, wherein said oscillator has a resonator connected between collectors of a pair of bipolar transistors having emitters connected in common, and one collector is cross-connected to the other base. circuit.   3. The voltage controlled oscillation circuit according to claim 1, wherein the oscillator is a Colpitts type oscillator having a grounded base or a grounded gate.   2. The voltage controlled oscillator circuit according to claim 1, wherein the oscillator is a single-phase output oscillator. An oscillator, a buffer amplifier cascode-connected to the oscillator, and a constant voltage generation circuit,
A voltage controlled oscillation characterized in that a power supply system connected to the buffer amplifier is separated, connected to the output of the constant voltage generation circuit, and the transistor of the output of the constant voltage generation circuit and the transistor of the buffer amplifier are shared circuit. The oscillator includes a resonator having a midpoint of an inductor as a node, and an operating current is supplied from the midpoint of the inductor, and the buffer amplifier is cascode-connected to the differential oscillator, and the operating current A differential buffer amplifier having a transistor pair operating as a tail current,
An output of the differential oscillator is input to the differential buffer amplifier, a base bias of the differential buffer amplifier is connected to an output of a constant voltage generation circuit to isolate a power supply system, and an output transistor of the constant voltage generation circuit 8. The voltage controlled oscillation circuit according to claim 7, wherein the transistor pair of the differential buffer amplifier is shared.   9. The voltage control according to claim 7, wherein the oscillator has a resonator connected between drains of a pair of field effect transistors having sources connected in common, and one drain is cross-connected to the other gate. Oscillator circuit.   9. The voltage controlled oscillation according to claim 7, wherein said oscillator has a resonator connected between collectors of a pair of bipolar transistors having emitters connected in common, and one collector is cross-connected to the other base. circuit.   9. The voltage controlled oscillation circuit according to claim 7, wherein the oscillator is a Colpitts type oscillator having a grounded base or a grounded gate.   8. The voltage controlled oscillation circuit according to claim 7, wherein the oscillator is a single-phase output oscillator.

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