JPH1188050A - Voltage controlled oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage controlled oscillator which has two oscillation stage transistors TR and can improve its C/N. SOLUTION: The oscillation stage TR 7 and 8 and a buffer stage TR 6 whose emitters are grounded via the resistors 17, 18 and 19 respectively are connected in parallel to each other. and a collector bias terminal 5 is connected to the TR 6 to 8 to be used in common among these TR collectors. Accordingly, the collector-emitter voltage is increased and the C/N is improved for the TR 6 to 8. Furthermore, the interlocking switch means 20 and 21 are added to inactivate the TR 6 when the TR 7 and 8 are inactive. In such a constitution, the power consumption is reduced for a voltage controlled oscillator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage controlled oscillator which is used in the UHF band and can be adapted to oscillate in, for example, two frequency bands which are nearly twice apart.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to the drawings.

FIG. 5 is a circuit diagram of a conventional voltage controlled oscillator. The voltage controlled oscillator is configured by inputting the outputs of the oscillation stages 1 and 2 to the buffer stage 32 via the capacitors 3 and 4. The data is output from the output terminal 14 from the buffer stage 32 via the capacitor 13. Resonance circuits 15 and 16 are connected to the oscillation stages 1 and 2, respectively, and both are connected to the control terminal 12. In the biasing method, a voltage is applied from the collector bias terminal 5 to the buffer transistor 6, the bias is applied from the emitter 9 to the oscillation transistor 7 or 8, and grounded via the resistor 17 or 18, respectively.

The operation of the conventional voltage controlled oscillator will be described below. Oscillation by the oscillation stage 1 and the resonance circuit 15 or oscillation by the oscillation stage 2 and the resonance circuit 16 is amplified by the buffer stage 32 and output from the output terminal 14. The switching of the oscillation frequency band is performed by the base bias terminals 1 of the oscillation stages 1 and 2.
Control is performed by applying voltages to 0 and 11. A voltage is applied so that when one of the base bias terminals 10 and 11 is on, the other is off. When both are off, no current flows through the oscillation stage transistors 7, 8 and the buffer stage transistor 6. The control of the oscillation frequency is performed by changing the resonance frequency of the resonance circuits 15 and 16 according to the voltage applied to the control voltage terminal 12.

[0005]

In the conventional voltage controlled oscillator, the oscillation stage transistors 7 and 8 and the buffer stage transistor 6 are connected in series because of the simplicity of the bias system. In this case, the oscillation stage transistor 7,
Since the collector-emitter voltage of No. 8 is small, it is difficult to improve C / N. As a method of improving the C / N ratio, an increase in the collector current of the oscillation stage transistors 7 and 8 can be considered. When the voltage between the collector and the emitter is fixed, the improvement is achieved to some extent. / N deteriorates. The best value of C / N is better as the voltage between the collector and the emitter is larger.

An object of the present invention is to improve the C / N of a voltage controlled oscillator having two oscillation stage transistors.

[0007]

In order to solve this problem, a voltage controlled oscillator according to the present invention comprises a first and a second oscillating stage transistors and a first and a second buffer stage transistors each having one end grounded to the emitter. The second and third resistors are connected, and the same power supply terminal is connected to the collector.
As a result, the voltage between the collector and the emitter of the two oscillation stage transistors can be increased, and a voltage controlled oscillator with improved C / N in two frequency bands can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a first, second and third oscillators, one ends of which are grounded at the emitters of the first and second oscillating stage transistors and the buffer stage transistor. Characterized in that the same power supply terminal is connected to the collector, and the first and second resonance circuits are connected to the bases of the first and second oscillation stage transistors, respectively. This has the effect that the voltage between the collector and the emitter of the oscillation stage transistor can be made larger than that of the conventional voltage controlled oscillator.

According to a second aspect of the present invention, a switch is provided at the base of each of the first and second oscillation stage transistors so that either one of the first and second oscillation stage transistors can be operated. The voltage controlled oscillator according to claim 1, wherein an oscillation frequency band can be switched.
It has the action of:

According to a third aspect of the present invention, the power supply terminal includes a second terminal.
3. The voltage controlled oscillator according to claim 2, wherein said switch means is opened when said first and second oscillation stage transistors are both inoperative. In the case of non-operation, there is an effect that no current flows through the circuit.

According to a fourth aspect of the present invention, in the first aspect, the fourth and fifth resistors, one ends of which are grounded, are connected to the bases of the first and second oscillation stage transistors, respectively. One ends of the sixth and seventh resistors are connected, and a first base bias terminal and an eighth terminal are connected to the other ends of the sixth resistors.
, A second base bias terminal and one end of a ninth resistor are connected to the other end of the seventh resistor, and the other end of the eighth resistor is connected to the base of a buffer stage transistor. A voltage-controlled oscillator, characterized in that the other end of a ninth resistor is connected to the circuit when the first and second oscillating stage transistors are inactive without using a second switch. It has the effect that no current flows.

According to a fifth aspect of the present invention, in the fourth aspect, instead of the eighth and ninth resistors, the first and second resistors are respectively provided.
The anode of the first diode is connected to the other end of the sixth resistor, the cathode is connected to the base of the buffer transistor, and the anode of the second diode is connected to the other end of the seventh resistor. And a cathode connected to the base of the buffer transistor, wherein the base bias current of the active oscillation stage transistor does not flow to the base bias circuit of the non-operating oscillation stage transistor. Has an action.

According to a sixth aspect of the present invention, the collectors of the first and second transistors whose emitters are grounded to the first and second base bias terminals, respectively, and the bases of the second and first transistors, respectively. 5. The voltage-controlled oscillator according to claim 4, wherein a base bias terminal voltage of the non-operating oscillation stage transistor becomes zero.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a first embodiment of the voltage controlled oscillator of the present invention.
An embodiment will be described.

The voltage controlled oscillator is constructed by inputting the outputs of the oscillation stages 1 and 2 to the buffer stage 32 via the capacitors 3 and 4. The data is output from the output terminal 14 from the buffer stage 32 via the capacitor 13. Resonance circuits 15 and 16 are connected to the oscillation stages 1 and 2, respectively,
Connected to In the bias method, a voltage is applied from the collector bias terminal 5 to the oscillation stage transistors 7 and 8. The same applies to the bias of the buffer stage transistor 6, except that a switch 20 is inserted between the collector bias terminal 5 and the buffer stage transistor 6. The emitters of the oscillating stage transistors 7, 8 and the buffer stage transistor 6 are grounded via resistors 17, 18, 19, respectively. The base bias has a structure in which a base bias terminal 22 is connected to the bases of the oscillation stage transistors 7 and 8 via a switch 21. Switch 21 and Switch 2
0 is linked so that the switch 20 is turned off when the switch 21 is turned off.

The operation of the voltage controlled oscillator according to the first embodiment of the present invention will be described below. Oscillation by the oscillation stage 1 and the resonance circuit 15 or oscillation by the oscillation stage 2 and the resonance circuit 16 is amplified by the buffer stage 32 and output from the output terminal 14.
The switching of the oscillation frequency band is performed by switching the switch 21. When a voltage is applied to one of the bases of the oscillation stage transistors 7 and 8, the other is not applied. When the switch 21 is off, that is, when both the oscillation stage transistors 7 and 8 are not operating, the switch 20 is turned off and the buffer stage transistor is also inoperative. The control of the oscillation frequency is performed by changing the resonance frequency of the resonance circuits 15 and 16 according to the voltage applied to the control voltage terminal 12.

This makes it possible to increase the voltage between the collector and the emitter of the oscillation stage transistors 7 and 8 as compared with the conventional voltage controlled oscillator. Further, when the voltage controlled oscillator is not operating, the circuit current does not flow, so that the power consumption can be reduced.

(Embodiment 2) FIG. 2 shows a voltage-controlled oscillator according to a second embodiment of the present invention.

The collectors of the oscillating stage transistors 7 and 8 and the buffer stage transistor 6 are all connected to the collector bias terminal 5, and the emitters are resistors 17 and 8, respectively.
Grounded via 18, 19. The bases of the oscillation stage transistors 7 and 8 are grounded via resistors 20 and 21, respectively.
One ends of 3, 24 are connected. The other ends of the resistors 23 and 24 are connected to base bias terminals 10 and 11, respectively.
7 are connected to base bias terminals 10 and 11, respectively. Resonance circuits 15 and 16 are connected to the bases of the oscillation stage transistors 7 and 8, respectively.
A control terminal 12 is connected to 5 and 16. The emitters of the oscillating stage transistors 7 and 8 are connected to capacitors 3 and
4, the buffer stage transistor 6 is input to the buffer stage transistor 6, and the collector of the buffer stage transistor 6 is connected to the output terminal 14 via the capacitor 13.

Next, the operation of the voltage controlled oscillator according to the second embodiment of the present invention will be described. The oscillation output from the oscillation stage 1 and the resonance circuit 15 or the oscillation output from the oscillation stage 2 and the resonance circuit 16 are input to the buffer stage 32 via the capacitors 3 and 4, respectively, amplified, and output from the output terminal 14. The switching of the oscillation frequency band is performed by switching the voltage applied to the base bias terminals 10 and 11. When a voltage is applied to one of the base bias terminals 10 and 11, the other is not applied. A case where a voltage is applied to the base bias terminal 10 will be described as a first example. The oscillation stage transistor 7 is applied with a base bias voltage, and operates as an oscillation circuit together with the resonance circuit 15. On the other hand, by applying a voltage to the base bias terminal 10, a voltage is also applied to the base of the oscillation stage transistor 8. However, since the voltage is lowered by the resistors 26, 27 and 24, the oscillation stage transistor 8 does not operate. The buffer stage transistor 6 operates with a base bias. Therefore, in the first example, the oscillation stage transistor 7 and the buffer stage transistor 6 operate, and operate as a voltage controlled oscillator. Conversely, when a voltage is applied to the base bias terminal 11, the oscillation stage transistor 8 and the buffer stage transistor 6 operate for the same reason, and operate as a voltage controlled oscillator. As a second example, the base bias terminal 1
If no voltage is applied to both 0 and 11, no base bias is applied to the buffer stage transistor 6, so that no current flows through the circuit.

The control of the oscillation frequency is performed by changing the resonance frequency of the resonance circuits 15 and 16 according to the voltage applied to the control voltage terminal 12.

This makes it possible to increase the voltage between the collector and the emitter of the oscillating stage transistors 7, 8 as compared with the conventional voltage controlled oscillator. Further, when the voltage controlled oscillator is not operating, the circuit current does not flow, so that the power consumption can be reduced.

In order to adjust the bias voltage of the buffer stage transistor 6, a series resistor or a resistor having one end grounded may be inserted into the base.

(Embodiment 3) FIG. 3 shows a voltage-controlled oscillator according to a third embodiment of the present invention.

Instead of the resistors 26 and 27, a diode 2
Since the structure is the same as that of the second embodiment except that the buffer stages 8 and 29 are used and the resistor 25 is inserted between the buffer stage transistor 6 and the diodes 28 and 29, detailed description of the circuit configuration is omitted.

Next, the operation of the voltage controlled oscillator according to the third embodiment of the present invention is the same as that of the second embodiment except that the operation related to the base bias voltage is different.
Description of other operations is omitted. As an example, a case where a voltage is applied to the base bias terminal 10 will be described. The oscillating stage transistor 7 is base-biased and enters an operating state. Further, the buffer stage transistor 6 is also base-biased and enters an operating state. However, since the base bias current to the oscillation stage transistor 8 is blocked by the diode 29, the oscillation stage transistor 8 does not operate. Also,
The base bias voltage of the oscillation stage transistor 7 is the resistance 2
0 and 23, and are not affected by the resistors 21 and 24. The base bias voltage of the buffer stage transistor 6 is determined by the resistor 25, and the resistors 21 and 24
Not affected by

This makes it possible to increase the voltage between the collector and the emitter of the oscillation stage transistors 7 and 8 as compared with the conventional voltage controlled oscillator. Further, when the voltage controlled oscillator is not operating, the circuit current does not flow, so that the power consumption can be reduced. Further, the base bias voltage of the active oscillation stage transistor 7 or 8 and the buffer stage transistor 6 is not affected by the resistance connected to the base of the non-operating oscillation stage transistor, so that the degree of freedom in design is large.

(Embodiment 4) FIG. 4 shows a voltage-controlled oscillator according to a fourth embodiment of the present invention.

The collectors of the transistors 30, 31 are connected to the base bias terminals 10, 11, respectively, the bases are connected to the base bias terminals 11, 10, respectively, and both emitters are grounded. The circuit configuration other than the above is the same as that of the second embodiment, and a detailed description of the circuit configuration will be omitted.

Next, the operation of the voltage-controlled oscillator according to the fourth embodiment of the present invention is the same as that of the second embodiment except that the operation relating to the base bias voltage is different, so that the description of the other operations is omitted. I do. As an example, a case where a voltage is applied to the base bias terminal 10 will be described. As in the second embodiment, the oscillation stage transistor 7 is base-biased and enters an operating state, and the buffer stage transistor 6 is also base-biased and enters an operating state. However, the reason why the oscillation stage transistor 8 does not operate is different from the second embodiment. Since the voltage is applied to the base bias terminal 10, the transistor 31 is in the operating state, and the voltage between the collector and the emitter becomes almost zero. Therefore, the base voltage of the oscillating stage transistor 8 becomes almost 0 and does not operate. At this time, the voltage between the base and the emic of the transistor 30 is also substantially zero, so that the transistor 30 does not operate. The base bias voltage of the oscillation stage transistor 7 can be determined by the resistors 20 and 23,
Not affected by 1,24. The base bias voltage of the buffer stage transistor 6 is determined by the resistors 26 and 27 and is not affected by the resistors 21 and 24.

This makes it possible to increase the voltage between the collector and the emitter of the oscillation stage transistors 7 and 8 as compared with the conventional voltage controlled oscillator. Further, when the voltage controlled oscillator is not operating, the circuit current does not flow, so that the power consumption can be reduced. Further, the voltage of the base bias terminal to which no voltage is applied is almost 0V. As a result, the base bias voltage of the active oscillating stage transistor and buffer stage transistor is not affected by the resistance connected to the base of the non-operating oscillating stage transistor. Furthermore, since the base potential of the non-operating oscillation stage transistor is fixed to 0, even if the oscillation signal of the active oscillation stage transistor goes around to the non-operational oscillation stage transistor, the non-operational oscillation stage transistor becomes abnormal. It can be prevented from operating.

[0032]

As is apparent from the above description, according to the present invention, the voltage between the collector and the emitter of the oscillating stage transistor of the voltage controlled oscillator capable of oscillating at two frequencies can be increased, N can be improved. Further, the circuit current when the base bias is not applied can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a voltage controlled oscillator according to a first embodiment of the present invention.

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

FIG. 3 is a circuit diagram of a voltage controlled oscillator according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a voltage controlled oscillator according to a fourth embodiment of the present invention.

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

[Explanation of symbols]

 Reference Signs List 1 oscillation stage 2 oscillation stage 3, 4 capacitor 5 collector bias terminal 6 buffer stage transistor 7, 8 oscillation stage transistor 9 emitter 10, 11 base bias terminal 12 control terminal 13 capacitor 14 output terminal 15, 16 resonance circuit 17, 27 resistor 28 , 29 Diode 30, 31 Transistor 32 Buffer stage

Claims (6)

[Claims] An emitter of each of the first and second oscillation stage transistors and a buffer stage transistor is connected to first, second, and third resistors, one end of which is grounded, and the same power supply terminal is connected to a collector. A voltage-controlled oscillator, wherein first and second resonance circuits are connected to bases or collectors of the first and second oscillation stage transistors, respectively. 2. A switching means is provided at a base of each of the first and second oscillation stage transistors to enable one of the first and second oscillation stage transistors to operate.
A voltage controlled oscillator as described. 3. A power supply terminal having a second switch means,
3. The voltage controlled oscillator according to claim 2, wherein said second switch means is opened when both of said first and second oscillation stage transistors are not operating. 4. The transistor according to claim 1, wherein fourth and fifth resistors each having one end grounded are connected to the bases of the first and second oscillation stage transistors, respectively, and further, the sixth and seventh resistors are respectively connected to the bases. , A first base bias terminal and one end of an eighth resistor are connected to the other end of the sixth resistor, and a second base bias terminal and a ninth terminal are connected to the other end of the seventh resistor. A voltage-controlled oscillator, wherein the other end of the eighth resistor and the other end of the ninth resistor are connected to the base of a buffer stage transistor. 5. The device according to claim 4, wherein first and second diodes are used instead of the eighth and ninth resistors, respectively, and the anode of the first diode is connected to the other end of the sixth resistor. And a cathode connected to the base of the buffer transistor, an anode of the second diode connected to the other end of the seventh resistor, and a cathode connected to the base of the buffer transistor. 6. The first and second base bias terminals are connected to collectors of first and second transistors each having an emitter grounded, and bases of the second and first transistors, respectively. The voltage controlled oscillator according to claim 4, wherein