| 摘要 |
PROBLEM TO BE SOLVED: To provide a temperature compensation system which has simple circuit configuration and high temperature compensation accuracy and consequently reduces noise and is made low-cost and is suitable for a portable telephone or the like. SOLUTION: The temperature compensation system includes: a crystal oscillation circuit 12 provided with a crystal vibrator 11; a varactor diode 14 whose capacitance varies with a voltage across the varactor diode 14; a temperature sensor section 101 for sensing ambient temperature; a function generator section 102 for generating a voltage approximate to a cubic function on the basis of a voltage from the temperature sensor section 101; a low pass filter section 103 for composing signals from the function generator section 102 and the temperature sensor section 101 to eliminate noise in the signals; and a reference voltage generating section 104 for applying a reference voltage of the function generator section 102 and the low pass filter section 103 to them. COPYRIGHT: (C)2005,JPO&NCIPI
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