| 摘要 |
In a PLL comprising a voltage controlled oscillator (VCO) equipped with a variable resonator, a frequency divider, a phase comparator, and an low pass filter (LPF), a variable resonator control signal generation section has the output voltage of the LPF as an input, detects a f/v sensitivity of the VCO, generates a variable resonator control signal, and controls a capacitance of the variable resonator by the variable resonator control signal. In a disclosed embodiment, when a voltage detection circuit having the output voltage of the LPF as an input detects a predetermined voltage, a data latch circuit transmits a variable resonator control signal based on the voltage detected by voltage detection circuit to variable resonator and performs a variable capacitance control. As a result, the f/v sensitivity of the VCO can be controlled to an optimal value even in the event of PLL configuration element variation or temperature changes.
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