Circuitry for switching effective electrode area on a crystal in a crystal oscillator to vary the oscillation frequency
First Claim
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1. A circuit for switching the effective electrode area on a crystal resonator in a crystal oscillator to vary the oscillation frequency, comprising:
- a crystal resonator suitable for use as a frequency standard;
plural electrodes on the surface of said crystal resonator jointly defining an electrode area;
pulse generator means for generating pulses having a variable duty factor; and
switching circuit means responsive to the pulses for switching the effective electrode area on the crystal resonator for controlling the oscillation frequency of said crystal resonator.
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Abstract
An oscillator comprises plural electrodes formed on a piezoelectric vibrator, and the oscillation frequency is controlled by varying the duty factor of the pulses for switching an effective electrode area of the plural electrodes. The frequency-temperature characteristic of the oscillator is compensated by varying the duty factor of the switching pulses according to temperature variations.
No trimmer condenser is needed, and the frequency-temperature characteristic is compensated over a wide temperature range.
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Citations
8 Claims
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1. A circuit for switching the effective electrode area on a crystal resonator in a crystal oscillator to vary the oscillation frequency, comprising:
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a crystal resonator suitable for use as a frequency standard; plural electrodes on the surface of said crystal resonator jointly defining an electrode area; pulse generator means for generating pulses having a variable duty factor; and switching circuit means responsive to the pulses for switching the effective electrode area on the crystal resonator for controlling the oscillation frequency of said crystal resonator. - View Dependent Claims (2)
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3. A circuit for switching the effective electrode area on a crystal resonator in a crystal oscillator to vary the oscillation frequency, comprising:
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a crystal resonator suitable for use as a frequency standard; plural electrodes on the surface of said crystal resonator jointly defining an electrode area; pulse generator means for generating pulses having a duty factor which varies according to the ambient temperature; and switching circuit means responsive to the pulses for switching the effective electrode area on the crystal resonator for controlling the oscillation frequency of said crystal resonator. - View Dependent Claims (4, 5)
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6. In combination:
- a crystal oscillator comprising a piezoelectric crystal resonator oscillatable at an oscillation frequency suitable for use as a frequency standard, a plurality of electrodes disposed on surfaces of the crystal resonator and jointly defining an electrode area, and circuit means for applying voltage to the plurality of electrodes to drive the crystal resonator to oscillate;
pulse generating means for generating pulses having a variable duty factor; and
switching means for switching at least one of the plurality of electrodes into and out of connection with the circuit means as a function of the pulse duty factor to thereby vary the effective electrode area and accordingly vary the oscillation frequency of the crystal resonator. - View Dependent Claims (7, 8)
- a crystal oscillator comprising a piezoelectric crystal resonator oscillatable at an oscillation frequency suitable for use as a frequency standard, a plurality of electrodes disposed on surfaces of the crystal resonator and jointly defining an electrode area, and circuit means for applying voltage to the plurality of electrodes to drive the crystal resonator to oscillate;
Specification