| 摘要 |
PURPOSE:To stabilize exquisitely an output frequency by impressing a prescribed control voltage in response to ambient temperature of a crystal resonator to a variable capacitor so as to compensate completely the temperature characteristic of the natural frequency of the crystal resonator over a wide temperature range. CONSTITUTION:An output signal of a temperature sensing element T detecting the ambient temperature of the crystal resonator X is converted from an analog signal into a digital signal through an A/D converting section 1 and inputted to a comparison discrimination section 2. A strong section 3 is connected to the section 2 and the temperature characteristic of the crystal resonator, that is, the natural frequency at each temperature is stored in the storage section 3. The comparison discrimination section 2 reads the natural frequency corresponding to the ambient temperature measured by the temperature sensing element T from the storage section 3 to calculate a deviation from the desired frequency, that is the corrected amount. A control voltage in response to the correction amount is generated by inputting the correction amount to a control voltage generating circuit 4 to impress the voltage to the variable capacitor V.
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