| 摘要 |
In a temperature compensation type crystal oscillator employing an indirect type temperature compensation system, if a low-voltage drive is to be achieved, although compensation is possible on a side of lower temperatures than the ordinary temperature and in the vicinity of the ordinary temperature, yet sufficient compensation effect can be obtained on a side of a higher-temperature end, so that it is necessary to establish a reference voltage (V<SUB>ref</SUB>) of a high value so as to achieve compensation of the higher-temperature end. Thus, there was a limit in the low-voltage drive. An approximate tertiary function compensation voltage from a compensation voltage generating circuit is supplied to the variable capacitance diode via a DC amplifier. Alternatively, a second compensation voltage generating circuit, which is separate from the first compensation voltage generating circuit, supplies a compensation voltage to the other terminal of the variable capacitance diode.
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