JPH02272902A - Oscillation circuit - Google Patents

Abstract

PURPOSE:To easily form a circuit to be an integrated circuit by completely symmetrically constituting the circuit and allowing only a direct current to flow from a power source. CONSTITUTION:Between the collectors of transistors 5 and 6, namely, between the bases of the transistors from the output of a differential amplifier circuit through ports 3 and 4 of a two-port surface acoustic wave resonator 2, namely, to the input of the differential amplifier circuit, positive feedback is executed and the circuit is oscillated. Then, the oscillation output can be obtained between output terminals 13 and 14. The completely balanced constitution is obtained to the whole circuit and a pair of the transistors 5 and 6 are operated as the differential amplifier circuit. When one current is increased, the other current is decreased. Accordingly, entire current is always fixed, and the high frequency current at the time of the oscillation does not flow to the direct current power source. Thus, the oscillation circuit can be obtained to be suitable for forming the integrated circuit without being a noise source to the other circuit and being hardly affected by the other circuit.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a highly stable oscillation circuit using a piezoelectric resonator such as a surface acoustic wave resonator, and particularly to an oscillation circuit suitable for integration. Regarding.

(Prior art) Oscillators using piezoelectric elements such as surface acoustic wave resonators and crystal oscillators have traditionally been used in television equipment, communication equipment, etc. where low-noise, highly stable frequency sources are required. is frequently used.

As an example, the most common Colpitts type oscillation circuit using five surface acoustic wave resonators is shown in FIG.

In FIG. 13, reference numeral 51 is an oscillation transistor, the base of which is connected to the positive terminal of the DC power supply 1 via a resistor 52, and to the load terminal via a resistor 53.
The collector is connected to the positive terminal of the power supply 1 through a resistor 54, the emitter is connected to the load terminal of the power supply 1 through a resistor 55,
As a result, a DC bias voltage and current are supplied to the transistor 51.

Further, a capacitor 58 for bypassing high frequency current is connected in parallel with the resistor 55, a capacitor 56 is connected between the base of the transistor 51 and the negative terminal of the power source 1, and a capacitor 57 is connected between the collector of the transistor 51 and the negative terminal of the power source 1. are connected to each other.

These capacitors 56 and 57 match the impedance of the surface acoustic wave resonator 49 connected in parallel between the collector and base of the transistor 51 with the impedance of this oscillation circuit to generate one oscillation.

Then, if the amplification degree of the transistor 51 is large enough,
With the circuit configuration as described above, oscillation occurs at the resonant frequency of the surface acoustic wave resonator 49, and a signal at the above frequency is output from the output terminal 61 connected to the collector of the transistor 51.

By the way, in terms of television equipment and communication equipment.

In order to make devices smaller, lighter, and cheaper, single-circuit integration is progressing. Therefore, integration of the oscillators used there is also desired. However, piezoelectric resonators such as surface acoustic wave resonators.

Since it is difficult to integrate the oscillator circuit on the same substrate as other circuits, integration of the oscillation circuit portion excluding the resonator is being considered.

However, in the case of a circuit like the one shown in Figure 13, three capacitors are required and it is not suitable for integrated circuits. This is because the shape is extremely large.

In particular, in FIG. 13, the absolute value of the impedance of the capacitor 58 must be sufficiently smaller than the resistance value of the resistor 55 at the oscillation frequency, and for that purpose, several tens of PF is required.
A capacity of ~ several hundred PF is required. In order to realize this level of capacity on an integrated circuit, 1ooo,'~
Although an area of approximately 112 mm is required, it is extremely uneconomical to spend this much area for one capacitor in an integrated circuit.

Furthermore, in the circuit shown in FIG. 13, the high frequency current flowing to the collector of the transistor 51 flows to the power supply 1 via the resistor 54 and the capacitor 58, but if other circuits are connected to the power supply 1, then this High frequency currents become a noise source for other circuits. Conversely, if noise from other circuits enters the line of power supply 1, the noise will enter the circuit via resistors 52, 54 and other elements because the circuit shown in Figure 13 is an unbalanced type. This may modulate the oscillation frequency or cause noise in the output signal. These effects become particularly noticeable when the oscillator shown in FIG. 13 and other circuits are mounted on the same integrated circuit board.

In this way, it was extremely difficult to integrate the conventional oscillation circuit as shown in FIG. 13 into an integrated circuit.

(Problems to be Solved by the Invention) As described above, conventional oscillation circuits using piezoelectric resonators such as surface acoustic wave resonators become a noise source for other circuits, and also reduce noise from other circuits. There were problems with making it into an integrated circuit because it was easily influenced and required a capacitor with a large capacity.

The present invention attempts to solve these problems, and its purpose is to provide an oscillation circuit suitable for integrated circuits that does not become a noise source for other circuits and is less susceptible to influence from other circuits. It is something to do.

[Structure of the invention]

(Means for Solving the Problems) The present invention connects each collector of a pair of transistors to one end of a DC power supply via a resistor having the same resistance value, and connects each emitter to one end of the DC power supply via a common current source. A differential amplifier circuit is constructed by connecting a bias circuit to the other end and applying a bias voltage to each base of the pair of transistors, and connecting the collector and base of one transistor of the pair of transistors on the same substrate. One port of a piezoelectric resonator having two sets of ports is connected to the transistor, and the other port is connected between the collector and base of the other transistor.

(Function) With the above-described configuration, the present invention allows the output of the differential amplifier circuit, that is, between the collectors of a pair of transistors, to be connected to the input of the differential amplifier circuit, that is, between the collectors of a pair of transistors, through a two-port piezoelectric resonator. Positive feedback is applied between the bases of the transistors at the resonance frequency of the two-port piezoelectric resonator, the circuit oscillates, and an oscillation output is obtained from the output of the differential amplifier circuit. According to this invention, the entire circuit has a perfectly balanced configuration. The pair of transistors operates as a differential amplifier circuit, and when the current of one increases, the current of the other decreases, so the overall current is always constant and no high-frequency current flows through the DC power supply during oscillation.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit configuration diagram according to an embodiment of the present invention.

In FIG. 1, transistors 5 and 6 are a transistor pair for differential amplification, and their respective collectors are connected to one end of a DC power supply 1 via resistors 8 and 9 having the same resistance value, respectively. Each emitter is connected to the other end of the DC power supply 1 via a common DC current source 7, and each base is connected to the output terminal of the bias circuit 10 via resistors 11 and 12 having the same resistance value. has been done. Note that the bias circuit 1o receives power from the DC power supply 1.

The above circuit constitutes a differential amplifier circuit, in which one port 3 of the two-point surface acoustic wave resonator 2 is connected between the collector and base of one transistor 5, and the other transistor 6 is connected between the collector and base of the differential amplifier circuit. The other port 4 is connected between the collector and the base.

Then, the AC voltage input between the bases of transistors 5 and 6 is amplified and output from between the collectors, but since the phases of voltage and current between transistors 5 and 6 are reversed due to differential operation, the two-point voltage is amplified and output from between the collectors. Ports 3 and 4 of the single-shaped surface acoustic wave resonator 2 are connected in polarity so that the voltages generated at the respective ports during resonance are in opposite phases.

The oscillation output of this circuit is output from output terminals 13 and 14 connected to the collectors of transistor 5 and transistor 6, respectively.
is taken out as a differential output.

Note that the electric field amplification between the input and output of the differential amplifier circuit configured with other elements except the two-point surface acoustic wave resonator 2, that is, the electric power input between the bases of the transistors 5 and 6 and the collector The ratio between the power and the power obtained from the two-point surface acoustic wave resonator 2 is set so as to sufficiently compensate for the loss of the two-point surface acoustic wave resonator 2.

This is determined by the characteristics of the transistor 5.6, the current value of the DC current source 7, the resistance values of the resistors 8 and 9, etc.

With the above configuration, the circuit shown in FIG.
Through the port 3 and port 4 of the two-point surface acoustic wave resonator 2, positive feedback is applied between the bases of the transistors 5 and 6, that is, to the input of the differential amplifier circuit, the circuit oscillates, and the output terminal 13 The oscillation output is obtained from between and 14.

However, if the parasitic capacitance between the transistors 5 and 6 and the parasitic capacitance between the ports of the two-point surface acoustic wave resonator 2 can be ignored, two-point surface acoustic wave resonance will occur as shown in Figure 1. When the child 2 is connected, negative feedback is applied to the differential amplifier instead of positive feedback. This is because without each of the above parasitic capacitances, transistor 5 and transistor 6
Since the transistor operates as an ideal transistor, the phase of the voltage applied between each base and the voltage generated between each collector is reversed by 180°. On the other hand, the phase of the voltage transmitted from one end of the port 3 of the two-point surface acoustic wave resonator to the other end of the boat 4 is approximately Oa at the resonant frequency. be.

However, in normal cases, each of the above parasitic capacitances cannot be ignored, and due to the time constants of the resistors 8 and 9 and the above parasitic capacitances,
The phase of the voltage generated between the collectors of transistors 5 and 6 is delayed from 180° by 360°, that is, 0.
Close to °. Therefore, by connecting the two-bottom surface acoustic wave resonator 2 as shown in FIG. 1, positive feedback can be applied to the differential amplifier.

The oscillation frequency at this time is the frequency at which the impedance of boats 3 and 4 of the two-point surface acoustic wave resonator is low, that is, the resonance frequency, but strictly speaking, the two-point surface acoustic wave resonator 2 The amount of phase change in the voltage transmitted from one end of port 3 and boat 4 to the other end of port 3 and the amount of phase change in voltage transmitted and amplified from between the bases of transistors 5 and 6 to between the collectors of transistors 5 and 6. The sum of the frequencies is an integer multiple of O゛ or 360°. Two-point surface acoustic wave resonator 2
In a very narrow frequency range centered around the resonant frequency, the phase change amount of the voltage between one end of the boat 3 and the boat 4 and the other end of the boat suddenly changes by about 180'. Therefore, the circuit oscillates at a frequency that satisfies the condition for the sum of the phase changes in a very narrow frequency range centered around this resonant frequency. However, as the distance from the resonant frequency increases, the impedance of ports 3 and 4 increases and loss increases, so the amplification degree of the differential amplifier circuit is required accordingly.

In addition, in FIG. 1, transistor 5 and transistor 6
The collector, base, and emitter DC potentials of both transistors are the same.

Therefore, the port 3 of the two-point surface acoustic wave resonator 2 connected between the respective collectors and bases of the transistors 5 and 6
The DC potentials of port 4 and port 4 are also the same.

Next, regarding the effect of the embodiment shown in FIG. 1, the power supply current flowing from the DC power supply 1 in the circuit shown in FIG.

The current flowing to the bias circuit 10 and the resistor 8. DC current source 7 via resistor 9, transistor 5, and transistor 6
It is only the current that flows through the Therefore, the current flowing through the DC power supply 1 is only a direct current, and no high-frequency current with one oscillation frequency flows. This is because the bias circuit 10 is
, 6, only direct current flows, and only a constant direct current flows through the direct current source 7.

This is because transistors 5 and 6 operate differentially in that when the current of one increases, the current of the other decreases, and the sum of the currents flowing through resistor 8 and resistor 9 is always constant. For this reason, even if another circuit is connected to the DC power supply 1, it will not become a noise source for the circuit shown in FIG. 1 or that circuit. Conversely, if noise occurs in the DC voltage supplied from DC power supply 1, in the circuit shown in Figure 1, the noise applied to the bases of transistors 5 and 6 through the bias circuit will be in phase, so The same applies to the noise that is canceled by the dynamic operation and does not appear in the output voltage between the collectors, and that enters through the resistors 8 and 9.

Furthermore, since the circuit in Figure 1 does not use a capacitor,
Extremely suitable for integrated circuits.

Note that the present invention is not limited to the above embodiments, and can be implemented with various modifications.

FIG. 2 is a circuit configuration diagram according to another embodiment of the present invention.

The circuit of this embodiment consists of transistor 5 and transistor 6.
A resistor 15 is connected instead of a DC current source between the connection point of the emitter and one end of the DC power supply. Even with such a connection, since transistors 5 and 6 operate as a differential pair, substantially the same effect as in the above embodiment can be obtained.

FIG. 3 is a circuit configuration diagram of an extremely easy-to-implement embodiment in which the bias circuit is composed of only resistors.

That is, in this embodiment, the voltage of the current source 1 is controlled by the resistor 1.
6 and resistor 17 and apply a bias voltage to the base of transistor 5, similarly, the voltage of DC power supply 1 is divided by resistor 1
8 and a resistor 19 to apply a bias voltage to the base of the transistor 6. In this case, the resistance values of the resistor 16 and the resistor 18 and the resistance values of the resistor 17 and the resistor 19 are the same value.

FIG. 4 is a circuit diagram of an embodiment suitable for use at high frequencies.

In this embodiment, the collector-emitter of the transistor 21 is connected in series with the collector of the transistor 5, and the collector-emitter of the transistor 22 is connected in series with the collector of the transistor 6.
The emitters of transistors 21 and 2 are connected, respectively.
A common bias voltage is applied from a bias circuit 20 to the bases of the two. By making such a connection, it becomes possible to use the device at a higher frequency than the embodiment shown in FIG.

This is because, in FIG. 4, the collector potential of transistors 5 and 6 is the value obtained by subtracting the base-to-emitter voltage of transistors 21 and 22 by approximately 0.7 V from the voltage applied from the bias circuit 20 to the bases of transistors 21 and 22. is fixed to , and remains almost constant even if one circuit is in an oscillation state.

For this reason, transistors 5 and 6 pose a problem especially at high frequencies.
This is because the effect of negative feedback of the collector alternating voltage to the base due to the parasitic capacitance between the collector and base of the transistors 5 and 6 can be reduced.

The other circuit operations are the same as the circuit shown in FIG. 1, except that the collector currents of transistors 5 and 6 flow through transistors 21 and 22, respectively.

FIG. 5 is a circuit configuration diagram according to still another embodiment of the present invention.

In this embodiment, not only is no DC voltage applied between the boat 3 and the port 4 of the two-bottom surface acoustic wave resonator 2, but also DC voltage is applied between the electrodes of the boat 3 and between the electrodes of the boat 4. This is so that no voltage is applied.

In the figure, the base of a transistor z7 whose collector is connected to one end of the DC power supply 1 is connected to the collector of the transistor 5, and the emitter of the transistor 27 is connected to the other end of the DC power supply 1 through a diode 29 and a resistor 31. connected to the terminal.

Similarly, the base of a transistor 28 whose collector is connected to one end of the DC power supply 1 is connected to the collector of the transistor 6, and the emitter of the transistor 28 is connected to the other terminal of the DC power supply 1 via a diode 30 and a resistor 32. It is connected. The port 3 of the two-point surface acoustic wave resonator 2 is connected not between the collector and base of the transistor 5, but between the connection point between the diode 29 and the resistor 31 and the base of the transistor 5; 4 is connected not between the collector and base of the transistor 6 but between the connection point between the diode 30 and the resistor 32 and the base of the transistor 6.

In this circuit, the collectors of the transistors 5 and 6 are determined by the voltage applied to the bases of the transistors S and 6 by the bias circuit 10, the resistance values of the resistors 8 and 9, and the current value of the DC current source 7. The DC bias voltage value between the bases is
The base-emitter voltage of the transistor 27.28,
It is designed to have the same voltage value as the sum of the voltages across the diodes 29 and 30. That is, no DC voltage is applied between the electrodes of port 3 and between the electrodes of port 4 of two-bottom surface acoustic wave resonator 2.

In this way, according to this embodiment, a DC voltage is applied not only between ports 3 and 4 of the two-bottom surface acoustic wave resonator 2, but also between the electrodes of port 3 and between the electrodes of port 4. It can be prevented from being applied.

Port 3 and port 4 of two-point surface acoustic wave resonator 2
The spacing between the electrode fingers that form the electrode is extremely narrow, only a few micrometers, and if water vapor or dust adheres to the electrode, and a DC voltage is applied between the electrodes, the electrode may be electrically corroded or destroyed due to electrical discharge. Sometimes it happens.

According to this embodiment, the two-bottom surface acoustic wave resonator 2
Deterioration and destruction can be prevented.

In addition, a transistor 27, a diode 29, and a resistor 31
The circuit consisting of the transistor 28, the diode 30, and the resistor 32 each operate as a so-called emitter follower type buffer amplifier, and the AC voltage applied to the bases of the transistors 27 and 28 is passed through this circuit. and is output to the two-point surface acoustic wave resonator 2. Therefore, the two-point surface acoustic wave resonator 2
Due to the impedance value of , the differential amplifier circuit is not significantly affected and stable oscillation can be obtained.

In addition, in FIG. 5, the output terminals 13 and 14 are respectively connected to the respective collectors of the transistors 5 and 6.
It may be connected to each base or each emitter of the transistors 27 and 28, or to the connection point between the diode 29 and the resistor 31, the connection point between the diode 30 and the resistor 32, or the like.

FIG. 6 is also a circuit configuration diagram according to another embodiment having the same purpose as the embodiment shown in FIG.

In this embodiment, the fifth diodes 29 and 30 are changed to resistors 33 and 34, respectively, and the resistors 3
1.32 have been changed to a DC current source 35 and a DC current source 36, respectively.

In the circuit of FIG. 6, transistor 5 and transistor 6
The DC bias voltage value between the collector and base of is the voltage between the base and emitter of the transistor 27 and 28 and the resistor 3.
The voltage value is designed to be the same as the sum of the voltages at both ends of 3.34. Note that the voltage across the resistor 33 and the resistor 34 is
It is determined by the resistance value of the resistor 33.34 and the current value of the DC current g35.36.

With the above configuration and design, the two-point surface acoustic wave resonator 2
DC voltage can be prevented from being applied between the electrodes of port 3 and between the electrodes of port 4.

In this way, this embodiment also prevents DC voltage from being applied between the electrodes of port 3 and between the electrodes of port 4 of two-point surface acoustic wave resonator 2, and between ports 3 and 4. can.

In FIG. 6, the output terminals 13 and 14 are connected to the collectors of the transistors 5 and 6, respectively, but also to the bases or emitters of the transistors 27 and 28, and also to the connection point 22 between the resistor 33 and the DC source 35. and resistance 34
may be connected to the connection point with the DC current source 36, etc.

In addition, diodes 29 and 30 in FIG. 5, and resistor 3 in FIG.
3 and 34 can be omitted.

In this case, the bias voltage between the collectors and bases of transistors 5 and 6 is set to be the voltage between the base and emitter of transistors 27 and 28, that is, about 0.7V.

FIG. 7 is a circuit configuration diagram according to another embodiment of the present invention.

In this embodiment, the emitters of transistors 5 and 6 are not connected to a direct current source and are each resistor 37.
and is connected to one end of the DC power supply 1 via a resistor 38. A capacitor 39 and a resistor 40 are connected between the emitter of transistor 5 and the emitter of transistor 6. Here, the capacitance value of the capacitor 39 is selected such that the absolute value of its impedance is sufficiently smaller than the resistance value of the resistor 40 at the resonance frequency of the two-bottom surface acoustic wave resonator 2.

With this configuration, the two-bottom surface acoustic wave resonator 2
At the resonant frequency of , the impedance of the capacitor 39 becomes sufficiently small, so that the circuit of FIG. 7 is isometrically almost the same as the circuit of FIG. 2.

oscillate. Also, at low frequencies, capacitor 3
Since the impedance of transistor 9 increases, transistor 5
and the amplification degree of the differential amplifier by transistor 6 decreases,
Unnecessary oscillations are prevented. In addition.

Here, unnecessary oscillation is oscillation at a frequency other than the resonant frequency caused by spurious, equivalent parallel capacitance, or the like of the two-point surface acoustic wave resonator.

Furthermore, by reducing the capacitance value of the capacitor 39, the circuit shown in FIG. It is possible to do so.

According to the present invention, it is also possible to configure an oscillation circuit that can vary the current consumption and oscillation output level of the entire circuit.

FIG. 8 is a circuit configuration diagram showing one embodiment thereof.

In FIG. 8, transistors 5 and 6 are a transistor pair that performs differential amplification, and their respective collectors are connected between the collectors and emitters of transistors 21 and 22, respectively.
It is connected to one terminal of the DC power supply 1 via resistors 8 and 9 having the same resistance value.

The emitters of the transistors 5 and 6 are connected to the other terminal of the DC power supply 1 through a common DC current source 60, and the bases of the transistors 5 and 6 are connected to the bias circuit 61 through resistors 11 and 12 having the same resistance value. connected to one output. The other output of the bias circuit 61 is directly connected to the bases of the transistors 21 and 22. Further, the bases of the transistors 27 and 28 whose collectors are connected to one terminal of the DC power supply 1 are connected to the transistors 21 and 2.
2 collectors, respectively. Each emitter of transistors 27 and 28 is connected to a transistor 6 whose base and collector are connected and which operates as a diode.
It is connected to the other terminal of the DC power supply 1 between the collectors 2 and 63 and through DC current sources 64 and 65. Note that the DC current sources 60, 64, and 65 have a function of varying the current value, and their control terminals are connected to the power control terminal 66. Further, the bias circuit 61 is connected to the DC power supply 1 to obtain power.

It has a function of varying the current consumption, and its control terminal is also connected to the power control terminal 66.

A differential amplifier is configured by the above circuit, and a two-point surface acoustic wave is connected between one terminal of the differential input, that is, the base of the transistor 5, and one terminal of the differential output, that is, the transistor 62 and the emitter. Port 3 of resonator 2 is connected, and similarly, port 4 is connected between the other terminal of the differential input, ie, the base of transistor 6, and the other terminal of the differential output, ie, the emitter of transistor 63. ing. Note that the output terminals 13 and 14 are connected to the respective bases of transistors 5 and 6, but these are connected to the respective collectors of transistors 21 and 22, the respective emitters of transistors 27 and 28, or the transistor 62.
and 63 emitters.

With the above configuration, the circuit of FIG. 8 operates as an oscillation circuit. Since this embodiment is basically a combination of the embodiments shown in FIGS. 4 to 6, the explanation of the oscillation operation and effects will be omitted, and the operation of varying the current consumption and output level will be explained below.

In the oscillation circuit shown in FIG. 8, all current flowing into the circuit from the DC power supply 1 flows through the DC current sources 60, 64, 65 and the bias circuit 61. The current values of these DC current sources 60, 64, and 65 and the current consumption of the bias circuit 61 can be varied by a signal applied to the power control terminal 66. That is, the current consumption of the entire circuit can be varied by the signal applied to the power control terminal 66. In some cases, it is possible to reduce the current consumption of the entire circuit to zero, stop the circuit operation, and enter a so-called standby state.

Further, when the current value of the DC current source 60, 64, 65 changes, the current value flowing through each transistor also changes, and therefore the degree of amplification as a differential amplifier circuit changes. Therefore, the current consumption of the entire circuit as well as the level of the oscillation output output from the output terminals 13 and 14 can be varied by the signal applied to the power control terminal 66.

As described above, the oscillation circuit shown in FIG. 8 can vary the current consumption and oscillation output level of the entire circuit. This kind of operation is the first
This can also be done by modifying the embodiments shown in Figures 3 to 6.

That is, by adding a current variable function to the DC current source 7 and bias circuits 10 and 20 of these embodiments, the current consumption and oscillation output level of the entire circuit can be varied.

In the embodiment shown in FIG. 8, if the variable current consumption and oscillation output level functions are not required, the DC current source 6
0.64.65 and the current variable function of the bias circuit 61 may be omitted. Even in this case.

Effects similar to those of other embodiments can be obtained.

The connection method of the two-point type surface acoustic wave resonator in the explanation of all the above embodiments and modified examples is based on the parasitic and capacitance of each transistor and the connection method of the two-point type surface acoustic wave resonator as explained in the example of FIG. This is a connection method when the parasitic capacitance between boats of surface acoustic wave resonators cannot be ignored. If each of these parasitic capacitances is negligible, for example, for the impedance of each of these parasitic capacitances at the oscillation frequency, resistor 8 and resistor 9
If the resistance value of is sufficiently low, if a two-port surface acoustic wave resonator or other two-port piezoelectric element is connected as shown in Figs. Positive feedback is not applied to the differential amplifier. In such a case,
By switching the connection between one end of one boat of a two-point surface acoustic wave resonator or other two-port piezoelectric element and the opposing end of the other boat, it is possible to Feedback can be applied to cause the circuit to oscillate.

FIG. 9 is a circuit configuration diagram showing an embodiment in which the parasitic capacitance of each transistor and the inter-port parasitic capacitance of a two-point surface acoustic wave resonator can be ignored. The boat 3 of the two-bottom surface acoustic wave resonator 2 is connected not between the collector and base of the transistor 5, but between the collector of the transistor 5 and the base of the transistor 6; It is connected not between the collector and base of transistor 6 but between the collector of transistor 6 and the base of transistor 5.

Although the embodiment of FIG. 9 is a modification of the embodiment of FIG. 1, similar modifications are possible in all embodiments.

Although the transistors 5 and 6 are all shown as bipolar transistors in the above embodiments and modifications, they are not limited to this, and may be, for example, field effect transistors.

FIG. 10 is a circuit configuration diagram using such field effect transistors, in which field effect transistors 23 and 24 are connected instead of bipolar transistors.

Further, the piezoelectric element is not limited to only a surface acoustic wave resonator, but may also be a two-port crystal resonator, a surface acoustic wave filter, a surface acoustic wave delay line, etc.

FIG. 11 is a circuit configuration diagram when a two-bottom crystal resonator is used, and instead of a two-bottom surface acoustic wave resonator, two
A port type crystal resonator 44 is connected.

Furthermore, the piezoelectric element is not limited to a two-boat type, and may have three or more ports. In this case, one or more of the boats may be used for oscillation output. It is possible to use

It is also possible to connect a plurality of boats in parallel or series to equivalently use a two-boat configuration.

FIG. 12 is a circuit configuration diagram when such a four-bottom surface acoustic wave resonator is equivalently used as a two-bottom surface acoustic wave resonator. boat 67
and the second boat 68 are connected in series, and the transistor 5
Similarly, a third port 69 and a fourth port 70 are connected in series and connected between the collector and base of the transistor 6. Even with such a configuration, the same operation and effect as the embodiment shown in FIG. 1 can be obtained.

In addition, in all the above embodiments, the output terminals 13 and 1
4 can be connected to each base of transistors 5 and 6 or to each gate of field effect transistors 23 and 24.

Several embodiments and modifications have been described above, but
In these examples, it is possible to make fine adjustments to the oscillation frequency.

For example, taking the embodiment shown in FIG. 1 as an example, between the collectors or bases of transistor 5 and transistor 6, between the collector of transistor 5 and one end of DC power supply 1, between the collector of transistor 6 and one end of DC power supply 1, or between the collector of transistor 5 and one end of DC power supply 1, or between the collector of transistor 5 and one end of DC power supply 1, or between the collector of transistor 5 and one end of DC power supply 1; 5 and one end of the DC power supply 1, and the base of the transistor 6 and one end of the DC power supply 1, etc., and the oscillation frequency may be finely adjusted by the capacitance value of the capacitor. The same goes for examples.

The embodiments and modifications of this invention have been described above, but
In short, this invention can be implemented in various modifications without departing from its gist. It is also possible to implement some of the embodiments and modifications described above in combination.

〔Effect of the invention〕

As explained above, according to the present invention, the circuit has a completely symmetrical configuration, and only direct current flows from the power supply. Therefore, it does not become a noise source for other circuits connected to the power supply.
Less susceptible to noise from other circuits. Furthermore, since a large capacitance capacitor is not required, it is extremely suitable for integrated circuits. Furthermore, since a piezoelectric element such as a surface acoustic wave resonator is used, oscillation at an extremely stable frequency can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram according to an embodiment of the present invention. 2 to 12 are circuit configuration diagrams showing other embodiments or modified examples of the present invention, and FIG. 13 is a circuit configuration diagram showing a conventional example. 1... DC power supply 2... 2-point surface acoustic wave resonator 3.4... Port 5.6... Transistor 7... DC current source 8.9... Resistor 10.・
・Bias circuit 11.12...Resistance 13.14
...Output terminal 20...Bias circuit 21.2
2...Transistor 27.28...Transistor 29.30...Diode 31.32...Resistor 39...Capacitor Figure 1 Figure 4 ('l') Dimension diagram (V') - Figure C) Dimensions

Claims (5)

[Claims] (1) Connect at least one port of a piezoelectric element having a plurality of ports between one terminal of the differential input and one terminal of the differential output of the differential amplifier circuit, and An oscillation circuit characterized in that another port of the piezoelectric element is connected between one terminal and the other terminal of the differential output. (2) Each collector of a pair of transistors is connected to one end of the DC power supply through a resistor with the same resistance value, and each emitter is connected to the other end of the DC power supply through a common current source, and each base is connected to one end of the DC power supply through a common current source. A differential amplifier circuit is constructed by connecting a bias circuit for applying a bias voltage, and one of the piezoelectric elements has two sets of ports on the same substrate between the collector and base of one of the transistors of the transistor pair. An oscillation circuit characterized in that the ports are connected to each other, and the other port is connected between the collector and the base of the other transistor of the transistor pair. (3) Each collector of a pair of transistors is connected to one end of the DC power supply through a resistor with the same resistance value, and each emitter is connected to the other end of the DC power supply through a common current source, and each base is connected to one end of the DC power supply through a common current source. A differential amplifier circuit is constructed by connecting a bias circuit that applies a bias voltage, and two sets of ports are provided on the same substrate between the collector of one transistor of the transistor pair and the base of the other transistor. 1. An oscillation circuit characterized in that one port of a piezoelectric element is connected to the oscillation circuit, and the other port of the piezoelectric element is connected between the base of the one transistor and the collector of the other transistor. (4) Each drain of a pair of field effect transistors is connected to one end of the DC power supply through a resistor having the same resistance value, and each source is connected to the other end of the DC power supply through a common current source, and each A differential amplifier circuit is constructed by connecting a bias circuit that applies a bias voltage to the gate, and two transistors are connected on the same substrate between the drain and gate of one of the field effect transistors of the pair of field effect transistors.
An oscillation circuit characterized in that one port of a piezoelectric element having a pair of ports is connected, and the other port is connected between the drain and gate of the other field effect transistor of the field effect transistor pair. (5) Each drain of a pair of field effect transistors is connected to one end of the DC power supply through a resistor having the same resistance value, and each source is connected to the other end of the DC power supply through a common current source, and each A differential amplifier circuit is constructed by connecting a bias circuit that applies a bias voltage to the gate, and an identical circuit is connected between the drain of one field effect transistor of the pair of field effect transistors and the gate of the other field effect transistor. Connecting one port of a piezoelectric element having two sets of ports on a substrate, and connecting the other port of the piezoelectric element between the gate of the one field effect transistor and the drain of the other field effect transistor. An oscillation circuit characterized by: