| 摘要 |
A voltage-controlled crystal oscillator having a voltage-variable capacitive element and a crystal vibrator, includes a control voltage generating circuit, a first charging circuit which charges an output-side capacitive component, a low pass filter having a first resistor and a first fixed capacitor, a timer circuit which outputs a control signal, a first switching element which is turned on in response to the control signal from the timer circuit so as to make both ends of the first resistor open-circuited, a second charging circuit to which a signal synchronized with the control signal is input, and a second fixed capacitor to which an output terminal of the second charging circuit is connected, and which connects a connection point between the first resistor and the first fixed capacitor. The low pass filter is arranged between the voltage-variable capacitive element and a connection point of the control voltage generating circuit and the first charging circuit.
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