Control circuit for thermostatic oven in oven controlled crystal oscillator

摘要

Provided is a control circuit for a thermostatic oven in an oven controlled crystal oscillator, which is capable of further improving stability of an oscillation frequency. A control circuit in which a thermistor (12) whose resistance value changes according to a temperature outputs a signal according to the ambient temperature of the thermostatic oven inside the oscillator, an operational amplifier (13) outputs a signal according to a difference between the output of the thermistor (12) and a reference signal, a power transistor (14) amplifies the output of the operational amplifier (13), and a heater (15) generates heat based on a collector voltage of the power transistor (14), is provided with a temperature sensor circuit (20) having a transistor (21) with a base to which the output of the operational amplifier (13) is input. The control circuit outputs a collector voltage of the transistor (21) as an internal temperature signal which changes according to a temperature inside the oscillator.