JPH01300604A - Voltage controlled piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To improve both the frequency temperature characteristic and the frequency power supply fluctuation characteristic by connecting a voltage stabilizing circuit outputting a stabilized voltage through a voltage across a constant voltage diode to a varactor diode. CONSTITUTION:A piezoelectric vibrator 7 is connected to one terminal of a varactor diode 6 and a voltage stabilizing circuit 13 is connected to the other end. The voltage stabilizing circuit 13 consists of a transistor(TR) 10, a constant voltage diode 9, and fixed resistors 11, 12 a base-emitter voltage of the TR 10 has negative temperature coefficient and the constant voltage diode 9 has a negative temperature coefficient at a voltage of 5.1V across the diode 9 or below. Even if any fluctuation exists in the power voltage applied to a DC terminal 15 by the voltage stabilizing circuit 13, the voltage across the constant voltage diode 9 is constant and compensated even if the power voltage at the DC terminal 15 is low. Thus, both the voltage control frequency temperature characteristic and the frequency power supply fluctuation characteristic are improved simultaneously by the addition of a few number of components.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voltage-controlled piezoelectric oscillator, and particularly to a voltage-controlled piezoelectric oscillator with improved frequency temperature characteristics and frequency power fluctuation characteristics.

[Conventional technology]

An example of a conventional voltage-controlled piezoelectric oscillator is shown in FIG. This piezoelectric vibrator includes a variable capacitance diode 26, a piezoelectric vibrator 27, an amplifier 25, fixed resistors 21 and 22, a variable resistor 28, and capacitors 23 and 24. In the figure, 29 is an external input terminal, 30 is a DC terminal, 3
1 is a ground terminal, and 32 is an output terminal.

According to this conventional voltage-controlled piezoelectric oscillator, the voltage input from the external input terminal 29 passes through the fixed resistor 22 to the cathode side of the variable capacitance diode 26, and also to the DC terminal 30.
The voltage applied to the variable resistor 28 is divided by the variable resistor 28 and applied to the anode side of the variable capacitance diode 26 via the fixed resistor 21. Therefore, when the voltage input from the external input terminal 29 changes, the capacitance value changes according to the CV characteristic of the variable capacitance diode 26 as shown in FIG. As a result, the oscillation frequency of the piezoelectric vibrator 27 changes, resulting in a voltage versus frequency characteristic as shown in FIG. In other words, the oscillation frequency increases as the external input voltage increases.

The oscillation frequency generated by the piezoelectric vibrator 27 is amplified by the amplifier 25 and output from the output terminal 17.

The frequency-temperature characteristics of the voltage-controlled piezoelectric oscillator described above depend on the temperature characteristics of the piezoelectric vibrator 27 and the temperature dependence of the variable capacitance diode 26. Graph line A in FIG. 5 shows the frequency-temperature characteristics of a conventional voltage-controlled piezoelectric oscillator, and the graph line A shows the frequency-temperature characteristics of a conventional voltage-controlled piezoelectric oscillator when the ambient temperature is T + , T 2 . T: indicates that as the value increases to +, the frequency increases.

In addition, the frequency power fluctuation characteristics of the voltage-controlled piezoelectric oscillator are
It depends on fluctuations in the power supply voltage applied to the DC terminal.

[Problem to be solved by the invention]

In order to improve the frequency-temperature characteristics of the conventional voltage-controlled piezoelectric oscillator described above, a thermistor may be used to compensate for the temperature characteristics of the piezoelectric vibrator 27, or a thermistor may be used to compensate for the temperature dependence of the variable capacitance diode 26. The oscillation circuit was constructed by combining this variable capacitance diode with a temperature compensation capacitor that has temperature characteristics that can cancel out the temperature dependence of the variable capacitance diode.

Further, to improve the frequency power supply fluctuation characteristics, a constant voltage diode was inserted in order to improve the fluctuation of the power supply voltage applied to the DC terminal.

In order to improve both the frequency temperature characteristics and the frequency power supply fluctuation characteristics in this way, many parts and special capacitors are required, which has the disadvantage of increasing the size of the circuit configuration and size.

Further, when the power supply voltage applied to the DC terminal 30 is a low voltage, the operating resistance of the voltage regulator diode becomes large, and the frequency power supply characteristics are not sufficiently improved.

The purpose of the present invention is to solve the above-mentioned problems, stabilize frequency-temperature characteristics without using a special temperature compensation capacitor, and
At the same time, it is an object of the present invention to provide a voltage-controlled piezoelectric oscillator whose frequency power fluctuation characteristics are stabilized even when a low voltage is used at the DC terminal.

[Means to solve the problem]

The present invention provides a voltage-controlled piezoelectric oscillator that includes a variable capacitance diode and a piezoelectric vibrator connected in series to one end of the variable capacitance diode, and in which an external input voltage is supplied to the one end. The present invention is characterized in that a voltage stabilizing circuit, which is composed of a diode and a fixed resistor and outputs a stabilized voltage based on the voltage across the constant voltage diode, is connected to the other end of the variable capacitance diode.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a voltage-controlled piezoelectric oscillator that is an embodiment of the present invention. This voltage-controlled piezoelectric oscillator includes a variable capacitance diode 6, a piezoelectric vibrator 7, an amplifier 5, a fixed resistor 1.2, a variable resistor B8, capacitors 3 and 4, and a voltage stabilizing circuit 13. have. In the figure, 14
is an external input terminal, 15 is a DC terminal, 16 is a ground terminal, and 17 is an output terminal. The voltage stabilizing circuit 13 consists of a transistor 10, a constant voltage diode 9, and a fixed resistor IL 12, and the base and emitter of the transistor 10 The voltage between them has a negative temperature coefficient, and the voltage regulator diode 9 also has a negative temperature coefficient below 5.1V. With this voltage stabilizing circuit 13, even if there is a fluctuation in the power supply voltage applied to the DC terminal 15, the voltage across the constant voltage diode remains constant, and this is compensated for even if the power supply voltage at the DC terminal is low. Ru.

Next, the operation of this embodiment will be explained. transistor 10,
The voltage generated by a voltage stabilizing circuit 13 consisting of a constant voltage diode 9 and fixed resistors 11 and 12 is divided by a variable resistor 8, and then passed through a fixed resistor 1 to a reference voltage on the anode side of a variable capacitance diode 6. is applied as . Transistor 100 base-emitter voltage V of voltage stabilizing circuit 13
! IE has a negative temperature coefficient, and the constant voltage diode 9 also has a
．． Since it has a negative temperature coefficient below 1V, as shown in FIG. 6, as the ambient temperature increases, the reference voltage decreases. Therefore, the voltage difference between the external input voltage from the external input terminal 14 and the reference voltage becomes small. As is clear from the C-■ characteristic of the variable capacitance diode shown in FIG. 3, as the voltage difference decreases, the capacitance value of the variable capacitance diode 6 increases and the frequency decreases. Its frequency-temperature characteristics are shown by broken line B in FIG. This characteristic makes it possible to compensate for the frequency-temperature characteristic of the conventional voltage-controlled piezoelectric oscillator, which is shown by graph line A in FIG. The graph 'faC in FIG. 5 shows the frequency-temperature characteristics of the improved voltage stabilizing circuit of this embodiment. In this way, the frequency is not affected by the ambient temperature, and a constant oscillation frequency can be obtained.

In addition, since the voltage stabilization circuit 13 is used, even if the power supply voltage applied to the DC terminal 15 fluctuates, a constant voltage can be applied to the anode of the variable capacitance diode 6, improving frequency power fluctuation characteristics. can do.

〔Effect of the invention〕

As described above, according to the present invention, the frequency temperature characteristics and frequency power fluctuation characteristics of a voltage controlled piezoelectric oscillator can be simultaneously improved by adding only a few components.

Furthermore, since the structure is composed of a semiconductor and a fixed resistor, it is easy to integrate and can be miniaturized.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a voltage controlled piezoelectric oscillator which is an embodiment of the present invention, Fig. 2 is a circuit diagram showing an example of a conventional voltage controlled piezoelectric oscillator, and Fig. 3 is a C-V of a variable capacitance diode. FIG. 4 is a diagram showing voltage control frequency characteristics, FIG. 5 is a diagram showing frequency temperature characteristics, and FIG. 6 is a diagram showing voltage temperature characteristics. 1, 2.11.12.21.22... Fixed resistor 3, 4.23.24... Capacitor 5.25
...Amplifier 6.26...Variable capacitance diode 7.27...
... Piezoelectric vibrator 8.28 ... Variable resistor 9 ... Constant voltage diode 10 ... Transistor agent Patent attorney Koden Yoshi Iwasa, fE Tadami Ihi "Koro" Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) In a voltage-controlled piezoelectric oscillator that includes a variable capacitance diode and a piezoelectric vibrator connected in series to one end of the variable capacitance diode, and an external input voltage is supplied to the one end, a transistor and a constant voltage diode are used. 1. A voltage-controlled piezoelectric oscillator, characterized in that a voltage stabilizing circuit comprising a fixed resistor and a voltage stabilized voltage across the constant voltage diode is connected to the other end of the variable capacitance diode.