JPH06196973A - Voltage control oscillator - Google Patents

Abstract

PURPOSE:To provide a voltage control oscillator capable of guranteeing stable operation in a high frequency area by executing the high speed switching operation of a transistor(TR) in a constant voltage part for determining logical amplitude and reducing the logical amplitude of the constant voltage part in accordance with the increase of oscillation frequency. CONSTITUTION:The voltage control oscillator is constituted of the 1st and 2nd constant voltage parts 1, 2 respectively consisting of resistors R2, R3, the 1st and 2nd TRs P3, P9 and the 1st and 2nd Schottky diodes D1, D2 connected between the base and collector electrodes of the TRs P3, P9, the 1st and 2nd emitter-follower parts 3, 4 respectively consisting of the 3rd and 4th TRs P11, P20 and constant current sources IU3, IU4, the 1st and 2nd switching TRs P4, P10, a capacitor C1, and a current source part 5 for supplying a current 11 for controlling the oscillation frequency of a voltage control oscillator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic IC P
The present invention relates to a voltage-controlled oscillator generally used as an oscillator for an LL circuit or the like, and in particular, enables a high-speed switching operation of a transistor of a constant voltage unit that determines the logical amplitude, and decreases the logical amplitude of the constant voltage unit as the oscillation frequency rises. By doing so, the present invention relates to a voltage-controlled oscillator that guarantees stable operation in a high frequency region and that is easy in frequency control.

[0002]

2. Description of the Related Art FIG. 5 shows a circuit diagram of a general voltage controlled oscillator as a first conventional example.

This conventional example is a circuit realized by an emitter-coupled multivibrator having a power supply voltage Vcc of 5 [V] or higher. Hereinafter, the operation principle will be described with reference to the voltage waveforms of respective parts shown in FIG. explain.

First, the voltage controlled oscillator does not operate unless either one of the transistors Q1 and Q2 is in the on state and the other is in the off state in the initial state. Here, it is assumed that the transistor Q1 is off and the transistor Q2 is on. Also,
It is assumed that the current I1 is such that the potential difference R · I1 turns on (conducts) the transistor (diode) Q6. Further, under the condition that the temperature is constant, the voltage drop between the base and the emitter when the transistor is in the on state is constant irrespective of the collector current, and this is VF.

In the above initial state, the base voltages of the transistors Q4 and Q1 are VB (Q4) = Vcc-VF, VB
(Q1) = Vcc-2VF, and at this time the transistor Q5 is in the off state, so VB (Q2) = Vcc. Since the base current IB (Q3) is so small that the transistor Q5 cannot be turned on and flows through the resistor R, the voltage drop of RIB (Q3) can be ignored. Therefore, the base voltage of the transistor Q2 is VB (Q2) = V
cc-VF and the emitter voltage is VE (Q2) = VCC-
It becomes 2VF.

Now, since the transistor Q1 is off and the transistor Q2 is on, the transistor Q2 continues to charge the capacitor C, and the emitter of the transistor Q1 is in a floating state, so the emitter voltage VE
(Q1) keeps falling.

Eventually, at the moment when the emitter voltage of the transistor Q1 becomes VE (Q1) = Vcc-3VF, the transistor Q1 changes from the off state to the on state. At this time, the collector current Ic (Q1) of the transistor Q1 flows, the transistor Q5 is turned on, and the transistors Q3 and Q3 are turned on.
The base voltage of 2 is VB (Q3) = Vcc-VF, VB (Q
2) = Vcc-2VF, the transistors Q2 and Q6 are turned off.

Therefore, the base voltage VB (Q1) of the transistor Q1 instantaneously rises by VF. However, the potential across the capacitor C cannot change instantaneously. The current I1 continues to charge the capacitor C from the opposite direction again, and the base voltage VB (Q2) of the transistor Q2 = Vcc-3VF
This state continues until (see FIG. 6C).

By repeating such a process, the conventional voltage controlled oscillator oscillates. As can be seen from the above operation principle, half of the oscillation cycle is equal to the charging time of the capacitor C. Therefore, if the cycle is T and the maximum value of the amount of charge accumulated in the capacitor C is Q, then Q = C · V = C ·
Since it is 2VF, from T / 2 = Q / I1, the oscillation frequency f becomes f = 1 / T = I1 / 4CVF (1).

Next, FIG. 7 shows a circuit configuration diagram of a second conventional voltage controlled oscillator. In this conventional example, the voltage controlled oscillator of the first conventional example described above is modified so that it can be used at a power supply voltage Vcc = 3 [V].

In the first conventional example, the logical amplitude of the output is VF =
While it is set to 0.8 [V] (at a temperature of 27 [° C.]), in the conventional example, the logical amplitude of the output is determined by the voltage drop of the resistors R7 and R9, and in the circuit example of FIG.
[V], the formula (1) is f = I1 / 0.06C. Another reason for lowering the logic amplitude of the output is to reduce the logic amplitude represented by the base-emitter voltage VF when the transistor is on in the above formula (1) so that the same current I1 is applied. , Higher frequencies can be obtained.

FIG. 8 shows changes in potential of each part in this conventional example with respect to time. This figure shows a simulation result by a well-known analog electronic circuit analysis simulator SPICE. The simulation was performed with each circuit constant shown in FIG. 7. In FIG. 8, the emitter voltage (a
-), The emitter voltage (a +) of the transistor Q12, the collector voltage (b-) of the transistor Q7, the collector voltage (b +) of the transistor Q12, the base voltage (c-) of the transistor Q7, the base voltage (c +) of the transistor Q12, Transistor Q17 collector voltage (d
-), And the collector voltage (d +) of the transistor Q19
Are shown respectively. Symbols in parentheses indicate nodes in FIG.

The biggest problem in the voltage controlled oscillator of this conventional example is the waveform of the collector voltage (b-) of the transistor Q7 and the collector voltage (b +) of the transistor Q11 which are the outputs of the circuit. The fall time of this waveform is determined by the time it takes for the current to flow from Vcc through the resistors RX and RX ', and the rise time is determined by the time when the transistor Q5 and the transistor (diode) Q13 move from the on state to the off state. .

As shown in FIG. 8, the waveforms of the collector voltage (b-) of the transistor Q7 and the collector voltage (b +) of the transistor Q11, which should originally be rectangular waves, have gentle peaks due to the slow rise and fall times. Drawing the shape of. Therefore, transistors Q17 and Q19
The differential amplifier consisting of does not switch at the correct time,
The on / off timings of the transistors Q7 and Q12 are deviated. This causes distortion of the waveforms of the emitter voltage (a-) of the transistor Q7 and the emitter voltage (a +) of the transistor Q11.

The emitter voltage of the transistor Q7 (a
-), Distortion of the waveform of the emitter voltage (a +) of the transistor Q12 hinders normal operation particularly when oscillating at a high frequency, and eventually causes deterioration of frequency characteristics.

[0016]

As described above, in the conventional voltage controlled oscillator, the rise and fall times of the collector electrode potential of the transistor of the constant voltage section that determines the logic amplitude are slow, and the on / off switching transistor is turned on and off. Has a problem in that it causes a distortion of the output voltage waveform, which hinders normal operation particularly when oscillating at a high frequency, and thus deteriorates the frequency characteristic.

The present invention solves the above problems,
The purpose is to enable high-speed switching operation of the transistor of the constant voltage part that determines the logic amplitude, and to reduce the logic amplitude of the constant voltage part as the oscillation frequency rises, thus ensuring stable operation in the high frequency range. It is to provide an oscillator.

[0018]

In order to solve the above-mentioned problems, the first feature of the present invention is, as shown in FIG. 1 (2), that the base electrode is a power source Vcc and the collector electrode is a resistor R2 or R3. First and second transistors P3 and P9 respectively connected to the power source Vcc via the first and second transistors
First and second constant voltage sections 1 and 2 including Schottky diodes D1 and D2 connected between the base and collector electrodes of the transistors P3 and P9, and the base electrode having the first or second constant voltage section. 1st and 2nd within 1 and 2
The third and fourth collector electrodes of the transistors P3 and P9 are connected to the power source Vcc, respectively.
Transistors P11 and P20, and the third and fourth transistors
First and second emitter follower sections 3 and 4 including constant current sources IU3 and IU4 connected between the emitter electrodes of the transistors P11 and P20 and the ground GND potential,
The base electrode serves as the fourth and third transistors P20 and P11 in the second or first emitter follower section 4 and 3.
The collector electrode to the emitter electrode of the first or second
First and second transistors P in the constant voltage sections 1 and 2 of
First and second switching transistors P4 and P10 respectively connected to the emitter electrodes of 3 and P9,
A capacitor C1 connected between the emitter electrodes of the first and second switching transistors P4 and P10.
And a current I for controlling the oscillation frequency of the voltage controlled oscillator.
1 is provided.

The second feature of the present invention is, as shown in FIG. 2, that the base electrode is a power source Vcc and the collector electrode is a resistor R.
First and second transistors P3 and P9 respectively connected to the power source Vcc via 2 and R3, and Schottky diode D1 connected between the base and collector electrodes of the first and second transistors P3 and P9. D2
And a first constant voltage portion including a base electrode as a collector electrode of the first and second transistors P3 and P9 in the first or second constant voltage portion, and a collector electrode as the power source Vcc. Third and fourth transistors P13 and P15 connected to each other, and constant current sources P14 and R5 and P15 and R6 connected between the emitter electrodes of the third and fourth transistors P13 and P15 and the ground potential.
A first and a second emitter follower part including a differential amplifier, a differential amplifier having the emitter electrode potentials of the third and fourth transistors P13 and P15 in the first and second emitter follower parts as inputs, and a base electrode To one or the other of the outputs of the differential amplifier, fifth and sixth transistors P11 and P20 having collector electrodes connected to the power supply Vcc, and the emitter electrodes of the fifth and sixth transistors P11 and P20 and the ground. Third including constant current sources P12 and R4 and P21 and R10 connected between potentials
And a fourth emitter follower part, and a base electrode as the emitter electrode of the sixth and fifth transistors P20 and P11 in the fourth or third emitter follower part, and a collector electrode in the first or second constant voltage part. The first and second
First and second switching transistors P connected to the emitter electrodes of the transistors P3 and P9, respectively.
4 and P10, a capacitor C1 connected between the emitter electrodes of the first and second switching transistors P4 and P10, and a current source unit that supplies a current that controls the oscillation frequency of the voltage controlled oscillator. That is.

Furthermore, a third feature of the present invention is that in the voltage controlled oscillator according to claim 1 or 2, the current source unit 5 includes the first and second current source units 5 as shown in FIG. The second constant voltage section 1 and 2 is provided with a current mirror circuit for flowing a predetermined offset current.

[0021]

In the voltage controlled oscillator of the first feature of the present invention, as shown in FIG. 1 (2), the first and second switching transistors P4 and P10 for generating the logical amplitudes at the on / off time are produced. The constant voltage sections 1 and 2 of No. 2 are configured by the first and second transistors P3 and P9 in which the Schottky diodes D1 and D2 are connected between the base and collector electrodes, so that the response time is short, that is, high-speed switching. It becomes possible to operate.

Further, in the voltage controlled oscillator of the second feature of the present invention, as shown in FIG. 2, the first and second switching transistors P are provided in the same manner as the voltage controlled oscillator of the first feature.
The Schottky diodes D1 and D2 are connected to the first and second constant voltage sections for generating the logic amplitudes when P and P10 are turned on / off.
Is constituted by the first and second transistors P3 and P9 connected between the base and collector electrodes,
A short response time, that is, a high-speed switching operation is possible, and the logical amplitudes at the collector electrodes of the first and second transistors P3 and P9 are increased as the current I1 is increased, that is, the oscillation frequency f is increased. ,
I try to make it smaller.

The input to the differential amplifier (the base electrodes of the transistors P17 and P19 forming the differential amplifier) is supplied to the first and second transistors P3 in the first and second constant voltage sections.
From the collector electrodes of P9 and P9 to the first and second emitter follower sections (third and fourth transistors P13 and P13).
15), the collector-emitter electrode voltages of the transistors P17 and P19 are secured to some extent to prevent the cutoff characteristic from deteriorating in the high frequency region.

Furthermore, in the voltage controlled oscillator of the third feature of the present invention, as shown in FIG. 1 (2) or FIG.
Is provided with a current mirror circuit, and even when the first and second transistors P3 and P9 are in the off state with respect to the first and second transistors P3 and P9 of the first and second constant voltage units 1 and 2, By passing a small amount of offset current (I1 / 10 in the circuit of FIG. 2) through the current mirror circuit, the first and second transistors P3 and P9 are not completely turned off, but are required for on / off switching. By shortening the time, high-speed switching operation is possible.

As a result, the collector potentials of the first and second constant voltage sections 1 and 2 in the off state of the first and second transistors P3 and P9 are respectively Vcc-R2.I.
1/10 and Vcc-R3 · I1 / 10, current I1
Becomes larger (as the oscillation frequency f becomes larger), the value decreases by the amount of the drop due to the offset current of the resistors R2 and R3, and the logic amplitude can be reduced.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a voltage controlled oscillator (VCO) according to a first embodiment of the present invention.
The circuit block diagram of is shown.

The voltage controlled oscillator of this embodiment is shown in FIG.
As shown in (1), it roughly comprises a voltage-current conversion circuit 10 for converting the input voltage Vi into a current I1, and a VCO main body 20 for changing the oscillation frequency f according to the change of the current I1. That is, the oscillation frequency f is controlled by the input voltage Vi.

The circuit configuration of the VCO main body 20 is shown in FIG.

The circuit of the VCO body 20 is roughly composed of a constant voltage section 1 and 2, an emitter follower section 3 and 4, a switching transistor pair P4 and P10, and a capacitor C.
1 and a current source unit 5.

In the constant voltage units 1 and 2, the base electrode is connected to the power source V.
The collector electrode is connected to cc (5 [V]) with a resistor R2 or R3.
It is composed of first and second transistors P3 and P9 connected to the power supply Vcc via the Schottky diodes D1 and D2 connected between the base and collector electrodes of the first and second transistors P3 and P9, respectively. The constant voltage unit 1 generates a voltage amplitude of VF when the first switching transistor P4 is in the ON state and 0 [V] when the first switching transistor P4 is in the OFF state, and the constant voltage unit 2 generates the voltage amplitude of the second switching transistor P4.
A voltage amplitude of VF is generated when 10 is in the on state, and 0 [V] is generated when it is in the off state.

The emitter follower units 3 and 4 drop the voltage generated by the constant voltage units 1 and 2 by VF (base-emitter voltage when the transistor is in the ON state-0.8 [V]) and are switching transistors. Pair P4 and P1
0 to the base electrode of the constant voltage section 1 and 2 of the first and second transistors P3 and P9.
To the collector electrode of the fifth and sixth transistors P11 and P20, respectively, which connect the collector electrode to the power supply Vcc.
And a constant current source I connected between the emitter electrodes of the fifth and sixth transistors P11 and P20 and the ground GND potential.
It consists of U3 and IU4.

In the first and second switching transistors P4 and P10, the base electrode is the emitter electrode of the sixth and fifth transistors P20 and P11 in the emitter follower sections 4 and 3, and the collector electrode is the constant voltage section. 1
, And 2 are connected to the emitter electrodes of the first and second transistors P3 and P9, respectively. The capacitor C1 is connected between the emitter electrodes of the first and second switching transistors P4 and P10.

Further, the current source section 5 is a section for supplying a current I1 for controlling the oscillation frequency f, and is composed of transistors P1 and P1.
2, P5, P6, P7, and P8. The transistors P5 and P6, and the transistors P7 and P8
Respectively constitute a current mirror circuit.

The difference between this embodiment and the first conventional example is the following two points.

(1) As the constant voltage section, a transistor in which a Schottky diode is connected between the base and collector electrodes instead of the diode is used.

(2) An offset current is applied to the transistor of the constant voltage section through the current mirror circuit.

The effect of the difference (1) is that by using the transistors P3 and P9 in which the Schottky diodes D1 and D2 are connected between the base and collector electrodes as the constant voltage units 1 and 2, the response time is short. That is, high-speed switching operation becomes possible.

The effect of the difference (2) is that a small amount of current is passed through the current mirror circuit with respect to the transistors P3 and P9 of the constant voltage sections 1 and 2 even when the first and second transistors P3 and P9 are off. By causing the offset current to flow, the first and second transistors P3 and P9 are not completely turned off, and the time required for on / off switching is shortened, thereby enabling high-speed switching operation.

Next, FIG. 2 shows a circuit configuration diagram of a voltage controlled oscillator according to a second embodiment of the present invention. In the figure, the same symbols are attached to the circuit elements that overlap with those of the first embodiment.

Similarly to the first embodiment, the voltage-controlled oscillator of this embodiment also has a voltage-current conversion circuit 10 for converting the input voltage Vi into a current I1 and a current I1 as shown in FIG. 1 (1).
VCO body 2 for changing the oscillation frequency f according to the change
It is composed of 0 and 0.

The circuit configuration of the VCO main body 20 of the second embodiment is shown in FIG.

The circuit of the VCO main body 20 roughly includes the first circuit.
And a second constant voltage section, first, second, third, and fourth emitter follower sections, a differential amplifier, switching transistor pairs P4 and P10, a capacitor C1, and a current source section.

The first and second constant voltage sections have first and second transistors P3 and P9, respectively, whose base electrode is connected to the power source Vcc and whose collector electrode is connected to the power source Vcc via the resistor R2 or R3. 1st and 2nd transistor P3
And Schottky diodes D1 and D2 connected between the base and collector electrodes of P9.

The first and second emitter follower sections have the base electrode as the first or second constant voltage section in the first or second constant voltage section.
The collector electrodes of the transistors P3 and P9 are connected between the third and fourth transistors P13 and P15, whose collector electrodes are connected to the power supply Vcc, and the emitter electrodes of the third and fourth transistors P13 and P15, and the ground potential. It consists of a constant current source. Each constant current source comprises a transistor P14 and a resistor R5, and a transistor P15 and a resistor R6.

The differential amplifier includes third and fourth transistors P13 and P in the first and second emitter follower sections.
The potential of the emitter electrode of 15 is input, and the output is supplied to the base electrodes of the fifth and sixth transistors P11 and P20 in the third and fourth emitter follower sections. The transistors P17 and P19, the resistors R7 and R9, And a transistor P18 as a constant current source and a resistor R8.

In the third and fourth emitter follower parts, the base electrode is connected to one or the other of the outputs of the differential amplifier, and the collector electrode is connected to the power source Vcc (3 [V]).
And a sixth transistor P11 and P20, and a constant current source connected between the emitter electrodes of the fifth and sixth transistors P11 and P20 and the ground potential. Each constant current source includes a transistor P12 and a resistor R4, and a transistor P21 and a resistor R10.

Further, the switching transistor pair P4
And P10, the base electrode is the emitter electrode of the fifth and sixth transistors P11 and P20 in the fourth or third emitter follower section, and the collector electrode is the first and the first constant voltage section in the first or second constant voltage section. 2 transistor P3
, And P9 emitter electrodes, respectively.
The capacitor C1 is connected between the emitter electrodes of the switching transistor pair P4 and P10.

Further, the current source section is a section for supplying a current I1 for controlling the oscillation frequency f, and is composed of the transistors P1, P2,
It consists of P5, P6, P7, and P8. The transistors P5 and P6 and the transistors P7 and P8 form a current mirror circuit, respectively.

The circuit configuration of FIG. 2 is a circuit configuration for performing a simulation with a well-known analog electronic circuit analysis simulator SPICE, and is a constant current instead of the current I1 supplied from the voltage-current conversion circuit 10. Source I
U1 and constant current source IU2 for simulation
And a peripheral circuit and a capacitor C2 are added respectively.

FIG. 3 shows the changes with time in the potential of each part in this embodiment. The same figure shows the above-mentioned simulation result. The simulation is performed with the circuit constants shown in FIG. 2. In FIG. 3, the emitter voltage (A−) of the first switching transistor P4, the emitter voltage (A +) of the second switching transistor P10, and the first transistor P3 are shown. Collector voltage (B-), second transistor P9
Collector voltage (B +), the base voltage (C−) of the first switching transistor P4, the base voltage (C +) of the second switching transistor P10, the collector voltage (D−) of the transistor P19, and the transistor P1.
No. 7 collector voltage (D +) is shown. still,
Symbols in parentheses indicate nodes in FIG.

The characteristic operation of this embodiment will be described below with reference to FIG.

The difference between this embodiment and the second conventional example is the following three points.

(1) A transistor in which a Schottky diode is connected between the base and collector electrodes instead of the diode is used as the constant voltage section.

(2) An offset current is applied to the transistor of the constant voltage section through the current mirror circuit.

(3) First and second inputs to the differential amplifier
Taken from the collector electrode of the transistor in the constant voltage part via the emitter follower part of.

As an effect of the difference (1), the Schottky diodes D1 and D2 are used as bases as the constant voltage section.
By using the first and second transistors P3 and P9 connected between the collector electrodes, the response time is short,
That is, high-speed switching operation becomes possible.

This is because the nodes b + and b- in FIG. 8 (the simulation result of the second conventional example) and FIG.
It is obvious by comparing the rising edges of the voltage waveforms at the nodes B + and B- at. From both figures, the first part of the constant voltage section
Also, it can be seen that the potential drop of the nodes B + and B- when the second transistors P3 and P9 are in the ON state is alleviated. Moreover, the difference between the two increases as the current increases. This means that the larger the current I1 is, the larger the logical amplitude at the nodes B + and B- of the present embodiment is than the logical amplitude at the nodes b + and b- of the second conventional example.
That is, it is shown that the higher the oscillation frequency f is, the smaller it is.

The difference (2) has the effect that a small amount of offset current is applied to the transistors P3 and P9 in the constant voltage section through the current mirror circuit even when the first and second transistors P3 and P9 are in the off state. By flowing (1/10 in the circuit of FIG. 2), the first and second transistors P3 and P9 are not completely turned off, and the time required for on / off switching is shortened. It enables various switching operations.
Further, by this, the collector potential (node B when the first and second transistors P3 and P9 of the constant voltage section are in the off state).
+ And B- potentials) are respectively Vcc-R2 · I1 / 1
0 and Vcc-R3 · I1 / 10. That is, the collector potential (potentials of the nodes B + and B−) when the transistors P3 and P9 are in the OFF state decreases by the amount of the drop due to the offset current of the resistors R2 and R3 as the current I1 increases, and the logic amplitude decreases.

Further, as an effect of the difference (3), the inputs to the base electrodes of the transistors P17 and P19 which form the differential amplifier are input from the collector electrodes of the first and second transistors P3 and P9 in the constant voltage section. , First and second
Emitter follower section (transistors P11 and P1
By taking it through 3), the collector-emitter electrode voltage of the transistors P17 and P19 is secured to some extent, and the deterioration of the cutoff characteristic in the high frequency region is prevented.

FIG. 4 is a diagram for explaining the oscillation frequency characteristic of this embodiment and the characteristic of the logical amplitude of the collector electrodes of the transistors of the first and second constant voltage sections.

First, with respect to the frequency characteristic of the oscillation frequency f, a characteristic closer to the theoretical value is obtained as compared with the second conventional example, and the collectors of the first and second transistors P3 and P9 of the constant voltage section are obtained. The logical amplitude Δv of the potential (potentials of the nodes B + and B−) has a characteristic that the higher the oscillation frequency, the smaller the characteristic amplitude Δv.
It is possible to control the logical amplitude according to the above, and it is possible to realize high-speed switching in a high frequency region.

[0063]

As described above, according to the voltage controlled oscillator of the first feature of the present invention, the first and second logical amplitudes for turning on / off the first and second switching transistors are produced.
Since the constant voltage section of the above is constituted by the first and second transistors in which a Schottky clamp diode is connected between the base and collector electrodes, a voltage controlled oscillator having a short response time, that is, capable of high-speed switching operation is provided. You can

Further, according to the voltage controlled oscillator of the second aspect of the present invention, similarly to the voltage controlled oscillator of the first aspect, a switching operation with a short response time, that is, a high speed is possible, and the transistor The logical amplitude in the collector electrode becomes smaller as the current becomes larger, that is, as the oscillation frequency becomes larger, to increase the switching speed in the high frequency region, and further, the input to the differential amplifier is Since it is taken from the collector electrodes of the transistors in the second constant voltage section and the first and second emitter follower sections, the collector-emitter electrode voltage of the transistors constituting the differential amplifier is secured to some extent. As a result, it is possible to provide a voltage controlled oscillator that can prevent deterioration of the cutoff characteristic in the high frequency region.

Further, according to the voltage controlled oscillator of the third feature of the present invention, the current source section is provided with the current mirror circuit, and the first and second constant voltage sections are provided with respect to the first and second transistors. Since a small amount of offset current is made to flow through the current mirror circuit even when the transistor is in the off state, the transistor is not completely turned off and the time required for on / off switching is shortened to achieve high-speed switching operation. As the current is increased (the oscillation frequency is increased), the collector electrode potentials of the first and second transistors of the first and second constant voltage sections are decreased by the resistance offset current. It is possible to control the logic amplitude according to the drive current by lowering the logic amplitude to reduce the logic amplitude, and high-speed switching is possible even in the high frequency range. It may provide a voltage controlled oscillator.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a voltage controlled oscillator according to a first embodiment of the present invention, FIG. 1 (1) is a schematic configuration diagram, and FIG.
(2) is a circuit configuration diagram of the VCO main body.

FIG. 2 is a circuit configuration diagram of a VCO main body of a voltage controlled oscillator according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a potential change with time in each unit of the second embodiment.

FIG. 4 is a diagram illustrating the oscillation frequency characteristic of the second embodiment and the characteristic of the logical amplitude of the collector electrodes of the transistors of the first and second constant voltage sections.

FIG. 5 is a circuit configuration diagram of a voltage controlled oscillator of a first conventional example.

FIG. 6 is a voltage waveform diagram of each part of the first conventional example.

FIG. 7 is a circuit configuration diagram of a voltage controlled oscillator of a second conventional example.

FIG. 8 is a diagram illustrating a potential change with time in each part of the second conventional example.

[Explanation of symbols]

1 1st constant voltage part 2 2nd constant voltage part 3 1st emitter follower part 4 2nd emitter follower part 5 Current source part 10 Voltage-current conversion circuit 20 VCO main body R1-R12, RX, RX 'resistance Q1 to Q23 transistors P1 to P23 transistors P4 first switching transistor P10 second switching transistor D1 and D2 Schottky clamp diode IU1 to IU4 constant current sources C1 and C2 capacitors Vcc power supply GND ground I1 current for controlling oscillation frequency (drive) Current) f oscillation frequency A +, A-, B +, B-, C +, C-, D +, D- node a +, a-, b +, b-, c +, c-, d +, d- node Vi input voltage Vo oscillation output

Claims (3)

[Claims] 1. A first transistor having a base electrode connected to a power source and a collector electrode connected to the power source via a resistor, and a first Schottky diode connected between a base electrode and a collector electrode of the first transistor. A first constant voltage section including a second transistor having a base electrode connected to the power supply and a collector electrode connected to the power supply via a resistor, and a second transistor connected between the base and collector electrodes of the second transistor. A second constant voltage section including a second Schottky diode, and a third constant voltage section connected to the collector electrode of the first transistor in the first constant voltage section and the collector electrode to the power source. A first emitter follower portion including a transistor and a first constant current source connected between an emitter electrode of the third transistor and a ground potential; The base electrode is connected to the collector electrode of the second transistor in the second constant voltage section, the collector electrode is connected to the fourth power supply, and the collector electrode is connected between the emitter electrode of the fourth transistor and the ground potential. A second emitter follower portion including a second constant current source, a base electrode for the emitter electrode of the fourth transistor in the second emitter follower portion, and a collector electrode for the first constant voltage portion in the first constant voltage portion. A first switching transistor connected to the emitter electrode of the second transistor, a base electrode to the emitter electrode of a third transistor in the first emitter follower section, and a collector electrode to the second electrode in the second constant voltage section. A second switching transistor connected to the emitter electrode of the transistor and the first and second switches, respectively. Capacitor and a voltage controlled oscillator and having a current source unit supplies a current for controlling the oscillation frequency of the voltage controlled oscillator is connected between the emitter electrodes of the ring transistor. 2. A first transistor having a base electrode connected to a power supply and a collector electrode connected to the power supply via a resistor, and a first Schottky diode connected between the base and collector electrodes of the first transistor. A first constant voltage section including a second transistor having a base electrode connected to the power supply and a collector electrode connected to the power supply via a resistor, and a second transistor connected between the base and collector electrodes of the second transistor. A second constant voltage section including a second Schottky diode, and a third constant voltage section connected to the collector electrode of the first transistor in the first constant voltage section and the collector electrode to the power source. A first emitter follower portion including a transistor and a first constant current source connected between an emitter electrode of the third transistor and a ground potential; The base electrode is connected to the collector electrode of the second transistor in the second constant voltage section, the collector electrode is connected to the fourth power supply, and the collector electrode is connected between the emitter electrode of the fourth transistor and the ground potential. A second emitter follower section including a second constant current source, an emitter electrode potential of a third transistor in the first emitter follower section, and an emitter of a fourth transistor in the second emitter follower section. A differential amplifier that receives the electrode potential and a base electrode as one or the other of the differential amplifier outputs,
A third emitter follower portion including a fifth transistor having a collector electrode connected to the power supply, and a third constant current source connected between the emitter electrode of the fifth transistor and the ground potential; and a base electrode To one or the other of the differential amplifier outputs,
A fourth emitter follower portion including a sixth transistor having a collector electrode connected to the power source, and a fourth constant current source connected between the emitter electrode of the sixth transistor and the ground potential; and a base electrode Is connected to the emitter electrode of the sixth transistor in the fourth emitter follower section, and the collector electrode is connected to the emitter electrode of the first transistor in the first constant voltage section. A second switching transistor connecting the emitter electrode of the fifth transistor in the third emitter follower portion and the collector electrode to the emitter electrode of the second transistor in the second constant voltage portion, respectively; A capacitor connected between the emitter electrodes of the second switching transistor and the voltage control A voltage-controlled oscillator, comprising: a current source unit that supplies a current that controls the oscillation frequency of the oscillator. 3. The voltage controlled oscillator according to claim 1, wherein the current source unit includes a current mirror circuit that causes a predetermined offset current to flow through the first and second constant voltage units.