| 摘要 |
A PLL system includes a phase comparator, charge pump, LPF, VCO, 1/N frequency divider, CRT drive circuit, and arithmetic unit. The charge pump outputs a charge pump signal in accordance with the phase error signal output from the phase comparator. The current capacity of the charge pump is controlled to keep a PLL loop gain constant by compensation for a variation in PLL loop gain due to a change in a frequency division ratio 1/N in the frequency divider.
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