JPH03283704A - Voltage controlled piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To suppress deterioration in frequency stability by providing an amplifier whose gain is controlled with an external voltage so as to suppress and hold fluctuation of a vibration energy constant corresponding to a voltage applied between terminals of a varactor diode and varying the vibration frequency of a piezoelectric vibrator. CONSTITUTION:When an external input voltage inputted from an external input voltage terminal is increased, a capacitance between terminals of a varactor diode 3 is decreased and the equivalent resistance of the varactor diode 3 is increased accordingly to decrease the oscillation strength, and the amplification factor of an amplifier 8 is increased as the external input voltage increases simultaneously to increase the stimulation level of a piezoelectric vibrator 4. As a result while keeping the oscillation strength constant, the frequency is increased. Conversely, when the external input voltage is decreased, the capacitance between the terminals of the varactor diode 3, the equivalent resistance of the varactor diode 3 is decreased accordingly to increase the excitation level of the piezoelectric vibrator 4, and simultaneously the amplification factor of the amplifier 8 is decreased as the external input voltage decreases thereby reducing the exciting level of the piezoelectric vibrator 4. Thus, the deterioration in frequency stability is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voltage-controlled piezoelectric oscillator, and more particularly to a voltage-controlled piezoelectric oscillator that uses a piezoelectric vibrator as an oscillation element and generates an oscillation output with a constant oscillation intensity.

[Conventional technology]

An example of a conventional voltage-controlled piezoelectric oscillator of this type is shown in FIG. The voltage controlled piezoelectric oscillator shown in FIG.
, fixed resistors 5 and 6, variable resistor 9, and amplifier 10
It is composed of:

According to this conventional voltage-controlled piezoelectric oscillator, the voltage input from the external input terminal is applied to the cathode side of the variable capacitance diode 3 via the fixed resistor 6, and the voltage applied to the DC terminal is applied to the variable resistor 9. The divided voltage is applied to the anode side of the variable capacitance diode 3 via the fixed resistor 5. When the voltage input from the external input terminal changes, the capacitance between the terminals of the variable capacitance diode 3 changes according to the C-■ characteristic as shown in FIG. 3, and as a result, the resonance frequency of the piezoelectric vibrator 4 changes, and the The voltage versus frequency characteristics are as shown in Figure 4.

In the voltage-controlled piezoelectric oscillator described above, when the external input voltage is increased, the capacitance between the terminals of the variable capacitance diode 3 decreases and the oscillation frequency increases, but at the same time, the equivalent resistance of the variable capacitance diode 3 increases, so the oscillation strength of the circuit decreases. decreases and oscillation stops.

To prevent this, in conventional voltage-controlled piezoelectric oscillators, the capacitance values of the two phase-inverting capacitors are set small so that sufficient oscillation strength can be obtained when the capacitance between the terminals of the variable capacitance diode 3 decreases. , or the amplification degree of the amplifier 10 was set high.

[Problem to be solved by the invention]

In the conventional voltage-controlled piezoelectric oscillator described above, when the external input voltage is reduced, the capacitance between the terminals of the variable capacitance diode 3 increases and the oscillation frequency decreases, and at the same time, the equivalent resistance of the variable capacitance diode 3 decreases. The disadvantage is that the excitation level of No. 4 becomes excessive, resulting in deterioration of oscillation frequency stability.

It is an object of the present invention to eliminate the above-mentioned drawbacks, to ensure sufficient oscillation strength when the oscillation frequency is increased, that is, when the capacitance between the terminals of the variable capacitance diode 3 decreases and the equivalent resistance increases, and to increase the oscillation frequency. To provide a voltage-controlled piezoelectric oscillator with a simple circuit configuration that suppresses a decrease in the excitation level of a piezoelectric vibrator when the level is lowered, that is, when the inter-terminal capacitance of a variable capacitance diode 3 increases and the equivalent resistance decreases.

[Means to solve the problem]

The oscillator of the present invention includes a piezoelectric vibrator, a variable capacitance diode that is connected in series with the piezoelectric vibrator, and controls the capacitance between the terminals by a voltage applied between the terminals, thereby making the vibration frequency of the piezoelectric vibrator variable. two phase inverting capacitors connected between each of the piezoelectric vibrator and the variable capacitance diode connected to ground to form a feedback section; In a voltage-controlled piezoelectric oscillator that includes an amplifier that supplies the variable capacitance diode and controls the oscillation frequency by the voltage applied to the variable capacitance diode, the voltage generated in response to an increase or decrease in the voltage applied to the variable capacitance diode. and an amplifier that controls the gain using an external voltage so as to suppress a decrease or increase in the oscillation intensity of the piezoelectric vibrator and keep the oscillation intensity constant and the frequency variable.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

The embodiment shown in FIG.
．． 7, an amplifier 8, and a variable resistor 9.

The amplifier 8 has a gain control voltage input terminal for controlling the gain with a voltage, and this input terminal is connected to an external input terminal through a fixed resistor 7. The anode of the variable capacitance diode 3 is connected to a DC terminal via a fixed resistor 5° variable resistor 9, and the cathode is connected to an external input terminal via a fixed resistor 6.

Next, the operation of this embodiment will be explained. When the external input voltage input from the external input voltage terminal is increased, the capacitance between the terminals of the variable capacitance diode 3 decreases, and the equivalent resistance of the variable capacitance diode 3 increases accordingly, trying to reduce the oscillation intensity, but at the same time As the external input voltage increases, the amplification degree of the amplifier 8 increases and the excitation level of the piezoelectric vibrator 4 increases.

As a result, the frequency increases while keeping the oscillation intensity constant. Conversely, when the external input voltage is reduced, the capacitance between the terminals of the variable capacitance diode 3 increases, the equivalent resistance of the variable capacitance diode 3 decreases accordingly, and the excitation level of the piezoelectric vibrator 4 tends to increase. At the same time, as the external input voltage decreases, the amplification degree of the amplifier 8 decreases, and the excitation level of the piezoelectric vibrator 4 decreases. As a result, the frequency is lowered while keeping the excitation level constant, so deterioration of frequency stability etc. can be prevented.

〔Effect of the invention〕

As explained above, according to the present invention, in a voltage-controlled piezoelectric oscillator, fluctuations in the vibration force corresponding to the voltage applied between the terminals of the variable capacitance diode to vary the vibration frequency of the piezoelectric vibrator are suppressed and held constant. By providing an amplifier whose gain is controlled by an external voltage, it is possible to prevent the oscillation from stopping and keep it constant with the excitation level, thereby suppressing deterioration of frequency stability.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an embodiment of the voltage controlled piezoelectric oscillator 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 variable circuit diagram of the voltage controlled piezoelectric oscillator of Fig. 2. A diagram showing an example of the C-■ characteristic of a capacitive diode, Figure 4 is
It is a figure which shows an example of the voltage control frequency characteristic by the voltage control piezoelectric oscillator of a figure. 1.2... Phase inversion capacitor, 3... Variable capacitance diode, 4... Piezoelectric vibrator, 5, 6.7... Fixed resistor, 8... Amplifier, 9... Variable resistor Vessel, 1o・
··amplifier.

Claims (1)

[Claims] a piezoelectric vibrator, a variable capacitance diode connected in series to the piezoelectric vibrator and controlling capacitance between the terminals by a voltage applied between the terminals to vary the vibration frequency of the piezoelectric vibrator; and a variable capacitance diode connected in series to the piezoelectric vibrator. 2 which is connected between each of the vibrator and the variable capacitance diode and the ground to form a feedback section.
a phase-inverting capacitor; and an amplifier that increases and outputs the oscillation output of the piezoelectric vibrator and supplies the output to the variable capacitance diode, the voltage being applied to the variable capacitance diode to control the oscillation frequency. In the controlled piezoelectric oscillator, a decrease or increase in the oscillation intensity of the piezoelectric vibrator that occurs in response to an increase or decrease in the voltage applied to the variable capacitance diode is suppressed to keep the oscillation intensity constant and the frequency variable. and an amplifier whose gain is controlled by an external voltage.