JP3387278B2 - Temperature compensated piezoelectric oscillator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensated piezoelectric oscillator having a buffer amplification output circuit having a DC constant voltage output function.

[0002]

2. Description of the Related Art A conventional temperature-compensated piezoelectric oscillator using an AT-cut crystal is generally provided with an oscillation frequency temperature compensation circuit including a negative characteristic thermistor and a resistor. The oscillation frequency temperature compensating circuit is normally connected to the power supply via a three-terminal regulator in order to keep the input / output voltage constant.

[0003]

However, since the conventional temperature-compensated piezoelectric oscillator has the three-terminal regulator, it occupies a large volume, which hinders its downsizing and cost reduction.

In view of this, the present invention eliminates the need for a three-terminal regulator and allows the buffer amplification output circuit to have the DC constant voltage output function of the conventional three-terminal regulator, thereby achieving a size reduction and cost reduction. An object is to provide a piezoelectric oscillator.

[0005]

Means for solving the problems of the present invention are as follows. 1. A temperature-compensated piezoelectric oscillator including a piezoelectric oscillation circuit, an oscillation frequency temperature compensation circuit that performs temperature compensation of the oscillation frequency of the piezoelectric oscillation circuit, and a buffer amplification output circuit that amplifies and outputs the oscillation output of the piezoelectric oscillation circuit. In the buffer amplification output circuit, the collector is connected to the power supply terminal through the load resistor.
First NPN type continuous transistor for buffered amplification output
Between the base of the first transistor and the ground
A constant voltage diode provided in the
For bypass provided between the base of the star and the ground
And a capacitor of the first transistor.
The oscillation output of the piezoelectric oscillation circuit input from the
The first transistor.
The temperature-compensated piezoelectric oscillator is characterized in that the emitter voltage is supplied as an input voltage to the oscillation frequency temperature compensation circuit via a choke coil .

2. The emitter voltage of the first transistor
The temperature-compensated piezoelectric oscillator according to claim 1, wherein a pressure is supplied to the piezoelectric oscillation circuit as an input voltage.

[0007] 3 . Wherein a second transistor of the piezoelectric oscillation circuit for oscillating, characterized in that said first transistor base voltage is applied to the base of said second transistor through a base bias resistor, to claim 2 The temperature-compensated piezoelectric oscillator described.

In the means described in 1, the buffer amplification output circuit having the buffer amplification output function is originally provided with the DC constant voltage output function, and this DC constant voltage output is used as the oscillation frequency temperature.
Supply to the compensation circuit . Then, to stabilize the input voltage of the oscillation frequency temperature compensation circuit <br/>, and temperature compensation to the oscillation frequency of the pressure conductive oscillation circuit, and outputs the oscillation frequency output from the buffer amplifier output circuit.

In the means described in 2 above, the buffer described above is used.
The DC constant voltage output of the amplification output circuit is also supplied to the piezoelectric oscillation circuit.
To do. This gives the oscillation frequency of the temperature-compensated piezoelectric oscillator.
Improve the stability of.

[0010]

[0011] In means of the third aspect provides via the base bias resistor the base voltage of the base in the buffer amplifier output circuit of the transistor of the piezoelectric oscillator. This further improves the stability of the oscillation frequency of the temperature-compensated piezoelectric oscillator.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a first embodiment of the temperature-compensated piezoelectric oscillator of the present invention. In the figure,
Reference numeral 1 is a buffer amplification output circuit, 2 is a piezoelectric oscillation circuit, and 3 is an oscillation frequency temperature compensation circuit. The circuit configurations of these circuit blocks will be described below.

The power supply terminal Vcc is connected to the collector of the buffer amplification NPN transistor TR1 of the buffer amplification output circuit 1 via a load resistor R4, and also to the ground via a series circuit of base bias resistors R1, R2 and R3. And is also connected to the ground via the decoupling capacitor C1. Transistor TR
The base of No. 1 is connected to the connection point of the resistors R1 and R2, is connected to the ground via the bypass capacitor C2, and is also a constant voltage diode, for example, the ground from the cathode of the Zener diode ZD via the anode. It is connected to the. Oscillation output is transistor TR
It is taken out from the collector of No. 1 through the coupling capacitor C3.

The emitter of the transistor TR1 is connected to the collector of the oscillating NPN transistor TR2 of the piezoelectric oscillation circuit 2 and also connected to the input terminal IN of the oscillation frequency temperature compensation circuit 3 via the choke coil L1.
The emitter of the transistor TR2 is the choke coil L2.
Is connected to ground via. The base of the transistor TR2 is connected to the ground through a series circuit of oscillation capacitors C4 and C5, and is connected to a connection point between the base bias resistors R2 and R3. As a piezoelectric oscillation element, for example, a crystal resonator X is used. Is connected to one end of.
The other end of the crystal resonator X is connected to the output terminal OUT of the oscillation frequency temperature compensation circuit 3 via the current limiting resistor R5 and is also connected to the ground via the varactor diode BD. In this case, the anode of the varactor diode BD is connected to the ground. The emitter of the transistor TR1 is connected to the connection point of the capacitors C4 and C5.

The oscillation frequency temperature compensating circuit 3 has a three-terminal structure of a coupling circuit of a resistor and a thermistor, and has an input terminal IN,
It has an output terminal OUT and a ground terminal GND.

Transistor TR1 of buffer amplification output circuit 1
And the transistor TR2 of the piezoelectric oscillation circuit 2 are connected in series between the power supply terminal Vcc and the ground.

The temperature-compensated piezoelectric oscillator of this embodiment has the above-described circuit configuration, and the operation will be described below.

Transistor TR1 of buffer amplification output circuit 1
Since the base potential of is kept constant by the Zener voltage of the Zener diode ZD, a constant voltage appears at the emitter of the transistor TR1. This constant voltage is applied to the collector of the transistor TR2 that constitutes the piezoelectric oscillation circuit 2 and stabilizes the base bias of the transistor TR2, thus stabilizing the oscillation characteristics thereof. Further, since this constant voltage is applied to the oscillation frequency temperature compensation circuit 3 via the choke coil L1, the input voltage of the oscillation frequency temperature compensation circuit 3 is stabilized.

The piezoelectric oscillator circuit 2 includes a transistor TR2,
The capacitors C4, C5, the crystal resonator X, the varactor diode BD and the like constitute a Colpitts oscillator circuit.
A compensation voltage for temperature compensation of the crystal resonator X is applied from the output terminal OUT of the oscillation frequency temperature compensation circuit 3 to the varactor diode BD, and the capacitance of the varactor diode BD is changed by this compensation voltage, and the oscillation constant of the Colpitts oscillation circuit. To compensate for changes in the oscillation frequency due to the temperature of the crystal resonator X.

Since the oscillation frequency of the piezoelectric oscillation circuit 2 is not directly output from the transistor TR2 but is output from the collector of the transistor TR1 having a buffer amplification function, it is stable without being affected by the voltage fluctuation and load fluctuation of the next stage. Oscillation can be continued.

The piezoelectric oscillation element may be a ceramic resonator, a surface acoustic wave resonator, a lithium tantalate resonator, a lithium niobate resonator, etc., in addition to the crystal resonator.

A temperature compensating diode may be connected in series to the Zener diode ZD in order to compensate for a change in the Zener voltage due to temperature.

In this embodiment, since the Zener diode ZD as a constant voltage diode is connected to the base of the transistor TR1 of the buffer amplification output circuit, the transistor TR1 is connected.
A constant voltage appears at the emitter of 1, and a constant voltage can be supplied to the piezoelectric oscillation circuit 2 and the oscillation frequency temperature compensation circuit 3 connected to this emitter, and the oscillation frequency is stabilized in combination with its original buffering action. be able to.

In the above embodiment, the varactor diode B is obtained by converting the change in the direct current resistance due to the temperature of the resistor-thermistor coupling circuit in the oscillation frequency temperature compensating circuit 3 into a voltage.
Although an indirect compensation circuit that controls the capacitance of D is used, a direct compensation circuit that directly controls the crystal oscillator by changing the complex impedance due to the temperature of the coupling circuit of the resistor and the thermistor may be used.

Although the Colpitts type oscillation circuit is shown as an example of the piezoelectric oscillation circuit 2 in the above embodiment, other oscillation circuits such as a Hartley type oscillation circuit and a Pierce type oscillation circuit may be used.

Next, a second embodiment of the temperature compensation type piezoelectric oscillator of the present invention will be described with reference to FIG. This second
The embodiment is similar to the first embodiment in that the buffer amplification output circuit 1
1. Piezoelectric oscillation circuit 12 and oscillation frequency temperature compensation circuit 1
3, circuit components such as resistors in each circuit block that perform the same function as in the first embodiment are given the same numbers as in the first embodiment.

In the buffer amplification output circuit 11, the power supply terminal Vcc is connected to the ground via the decoupling capacitor C1 and is also connected to the collector of the buffer amplification NPN transistor TR1 via the load resistor R4. Transistor TR via bias resistor R1
1 is connected to the base. The collector of the transistor TR1 is output via the coupling capacitor C3. The base of the transistor TR1 is connected to the ground via the bypass capacitor C2 and the Zener diode ZD. In this case, the Zener diode ZD has its cathode connected to the base of the transistor TR1. A direct-current coupling capacitor C6 and a choke coil L1 are connected to the emitter of the transistor TR1.

Next, in the piezoelectric oscillation circuit 12, the power supply terminal Vcc is connected to the collector of the oscillation NPN transistor TR2 via the load resistor R6 and to the base of the transistor TR2 via the base bias resistor R2. It is connected. The collector of the transistor TR2 is connected to the emitter of the transistor TR1 of the buffer amplification output circuit 11 via the capacitor C6. Also,
The base of the transistor TR2 is a capacitor C for oscillation.
It is connected to the ground through the series circuit of C4 and C5 and the base resistor R4, and is also connected to one end of the crystal resonator X. The emitter of the transistor TR2 is connected to the ground via the choke coil L2, and
It is connected to the connection point of the capacitors C4 and C5. The other end of the crystal resonator X is connected to the ground via the varactor diode BD and is also connected to the current limiting resistor R5. In this case, the anode of the varactor diode BD is connected to the ground.

Next, the oscillation frequency temperature compensating circuit 13
It consists of a resistor and thermistor coupling circuit and has an input terminal I
It has a three-terminal structure of N, an output terminal OUT, and a ground terminal GND. The input terminal IN is a buffer amplification output circuit 11
To the emitter of the transistor TR1 of the choke coil L1
Connected through. The output terminal OUT has a resistor R5
Is connected to the connection point between the crystal resonator X and the varactor diode BD.

Although the present embodiment has the above-mentioned circuit configuration, the operation will be described below. Buffer amplification output circuit 1
Since the base potential of the first transistor TR1 is kept constant by the Zener voltage of the Zener diode ZD, a constant voltage appears at the emitter of the transistor TR1. Since this constant voltage is applied to the oscillation frequency temperature compensation circuit 13 via the choke coil L1, the input voltage of the oscillation frequency temperature compensation circuit 13 is stabilized.

The piezoelectric oscillator circuit 12 includes a transistor TR.
2, the capacitors C4 and C5, the crystal resonator X, the varactor diode BD and the like constitute a Colpitts oscillation circuit. A compensation voltage for temperature compensation of the crystal resonator X is applied from the output terminal OUT of the oscillation frequency temperature compensation circuit 13 to the varactor diode BD, and the capacitance of the varactor diode BD is changed by this compensation voltage, and the oscillation constant of the Colpitts oscillation circuit. To compensate the fluctuation of the oscillation frequency due to the temperature of the crystal resonator X.

The oscillation frequency output of the piezoelectric oscillation circuit 12 is input from the collector of the transistor TR2 to the emitter of the transistor TR1 via the capacitor C6, amplified, and output from the collector.

In the present embodiment, since the Zener diode ZD is connected as the constant voltage diode to the base of the transistor TR1 of the buffer amplification output circuit 11, a constant voltage appears at the emitter of the transistor TR1 and the oscillation connected to this emitter. A constant voltage can be supplied to the frequency temperature compensating circuit 13, and the oscillation frequency can be stabilized in combination with its original buffer amplification function.

[0034]

According to the present invention, the stable output voltage of the buffer amplification output circuit having the buffer amplification output function and the DC constant voltage output function is supplied to the oscillation frequency temperature compensation circuit. The input voltage of the temperature compensation circuit is stabilized, and the compensation characteristic of the oscillation frequency temperature compensation circuit is also stabilized. At the same time, since the buffer amplification output circuit has the DC constant voltage output function of the conventional three-terminal regulator, the three-terminal regulator is not required, and downsizing and cost reduction are realized.

According to the second aspect of the invention, the stable output voltage of the buffer amplification output circuit having the buffer amplification output function and the DC constant voltage output function is also supplied to the piezoelectric oscillation circuit.
This stabilizes the input voltage of the piezoelectric oscillator circuit,
The sex is stable.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a temperature compensated piezoelectric oscillator according to a first embodiment of the invention.

FIG. 2 is a circuit diagram of a second embodiment of the temperature-compensated piezoelectric oscillator of the present invention.

[Explanation of symbols]

1, 11 Buffer amplification output circuit 2, 12 Piezoelectric oscillation circuit 3, 13 Oscillation frequency temperature compensation circuit TR1 and TR2 transistors ZD Zener diode BD Varactor diode X crystal resonator

Claims (3)

(57) [Claims] 1. A piezoelectric oscillation circuit, an oscillation frequency temperature compensation circuit that performs temperature compensation of an oscillation frequency of the piezoelectric oscillation circuit, and a buffer amplification output circuit that amplifies and outputs an oscillation output of the piezoelectric oscillation circuit. In the temperature-compensated piezoelectric oscillator, the buffer amplification output circuit has a collector via a load resistor.
First NPN type for buffer amplification output connected to power supply terminal
Transistor and the base and ground of the first transistor
A constant voltage diode provided between the land and
Provided between the base of one transistor and ground
And a bypass capacitor, and
The oscillation of the piezoelectric oscillation circuit input from the emitter of the transistor
The output voltage of the first transistor is a choke coil.
Temperature-compensated piezoelectric oscillator and supplying an input voltage to the oscillation frequency temperature compensation circuit through Le. 2. The emitter voltage of the first transistor
The and supplying as an input voltage to the piezoelectric oscillation circuit, the temperature-compensated piezoelectric oscillator of claim 1. Wherein a second transistor for the piezoelectric oscillator is oscillating, and characterized in that the base voltage of the first transistor is applied to the base of said second transistor through a base bias resistor The temperature-compensated piezoelectric oscillator according to claim 2 .