| 摘要 |
<p>PURPOSE: To enhance the effect with stable frequency over a wide temperature range by changing a reactance of a crystal vibrator based on a frequency correction signal outputted from a control circuit to inversely correct the mean value of the frequency temperature characteristic. CONSTITUTION: An ambient temperature of the radio communication equipment 11 is detected by a temperature detection circuit 73 and a voltage generated across a thermister is monitored by a control circuit 3. When ambient temperature decreases below to a temperature compensation range of a crystal oscillator 71, it is detected by the circuit 3. Then the circuit 3 reads a frequency correction signal used to inversely correct a frequency temperature characteristic of the crystal vibrator from a storage circuit 74 by using a voltage outputted from the circuit 73 as an address point and converts the signal into a voltage, which is fed to a variable capacitor in a frequency correction circuit 72 to change the capacitance. Thus, the frequency temperature characteristic of the crystal vibrator is inversely corrected to correct the oscillating frequency of the oscillator 71. Even when the temperature decreases, the temperature characteristic changes properly to allow the oscillator 71 to oscillate a prescribed frequency.</p> |
