Invention Grant
US08576970B2 Phase-locked loop 有权
锁相环

Phase-locked loop
Abstract:
A PLL circuit (1a, 1b) for generating a pixel-clock signal based on a hsync signal. The PLL circuit comprises a phase-frequency detector arranged to receive the hsync signal and a frequency divided pixel-clock signal, and generate up and down signals based on the hsync signal and the frequency-divided pixel-clock signal. A charge pump (20) is arranged to generate an output signal based on the up and down signals and a loop filter (30) is arranged to generate a frequency-control signal based on the output signal of the charge pump (20). Furthermore, a VCO (40a, 40b) is arranged to generate an oscillating signal and adjust the frequency of the oscillating signal in response to the frequency-control signal. The VCO (40a, 40b) is adapted to have a tuning range with a center frequency which is larger than or equal to 4 GHz. A programmable first frequency divider (50) is arranged to generate the pixel-clock signal by frequency division of the oscillating signal, and a programmable second frequency divider (60) is arranged to generate the frequency divided pixel-clock signal by frequency division of the pixel-clock signal.
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