摘要 |
Aspects of the disclosure provide a phase-locked loop (PLL). The PLL includes a voltage-controlled oscillator (VCO), a detector module, and a ramp module. The VCO has a first capacitor unit and a second capacitor unit. The VCO is configured to generate an oscillating signal having a frequency based on a first capacitance of the first capacitor unit and a second capacitance of the second capacitor unit. The detector module is configured to generate a voltage signal as a function of the oscillating signal and a reference signal. The voltage signal is used to control the first capacitor unit to stabilize the frequency of the oscillating signal. The ramp module is configured to generate a ramp signal based on the voltage signal. The ramp signal is used to control the second capacitor unit to ramp the second capacitance from a first value to a second value.
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