Oscillation circuit
AssigneeMurata Manufacturing Co., Ltd.
InventorRyuhei Yoshida
Life of this patent
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Abstract
A Colpitts-type oscillation circuit, employing a ceramic resonator vibrating in the energy trapping thickness shear slide mode is disclosed in which, an antiresonance frequency of the ceramic resonator has a negative temperature characteristic which is less step than that of its resonance frequency. Capacitance between terminals of the ceramic resonator is set so that an oscillation frequency (Fosc) of the oscillation circuit at the ordinary temperature is higher than a central frequency ((Fr+Fa)/2) of the ceramic resonator. Thus, it is possible to employ a ceramic resonator having a large bandwidth (.DELTA.F), thereby improving the temperature characteristic of the oscillation frequency.
Claims14
An oscillation circuit of the Colpitts-type having a ceramic resonator vibrating in the energy trapping thickness shear slide mode, wherein:
- a resonance frequency Fr of said ceramic resonator has a first negative temperature characteristic,
- an antiresonance frequency Fa of said ceramic resonator has a second negative temperature characteristic which is less steep with respect to temperature than that of said resonance frequency Fr, and
- a capacitance C.sub.F between a pair of terminals of said ceramic resonator is set so that an oscillation frequency Fosc of said oscillation circuit is higher than a central frequency ((Fr+Fa)/2) of said ceramic resonator, thereby causing a temperature characteristic of said oscillation frequency to be determined more by said second negative temperature characteristic than by said first negative temperature characteristic.
A method of improving the temperature characteristic of an oscillation frequency of an oscillation circuit, comprising the steps of:
- (A) providing an oscillation circuit of the Colpitts-type having a ceramic resonator vibrating in the energy trapping thickness shear slide mode, wherein:
- (i) a resonance frequency Fr of said ceramic resonator has a first negative temperature characteristic, and
- (ii) an antiresonance frequency Fa of said ceramic resonator has a second negative temperature characteristic which is less steep with respect to temperature than that of said resonance frequency Fr;
- and
- (B) setting a capacitance C.sub.F between a pair of terminals of said ceramic resonator so that an oscillation frequency Fosc of said oscillation circuit is higher than a central frequency ((Fr+Fa)/2) of said ceramic resonator, thereby causing a temperature characteristic of said oscillation frequency to be determined more by said second negative temperature characteristic than by said first negative temperature characteristic.
Dependencies are inferred from the claim text.