| 摘要 |
PROBLEM TO BE SOLVED: To provide a PLL system and its method for compensating current leak which may include gate-leak current attributable to a gate capacitor. SOLUTION: A compensation current is supplied to an input node of a voltage-controlled oscillator (VCO) to substantially compensate current leak, and accordingly, reduce PLL jitter. The PLL circuit includes a compensation charge pump which receives input from a counter, and then provides a counter-value-proportional compensation current. The counter value increments and decrements according to up and down inputs from a phase frequency detector. The counter value is fixed when the PLL circuit is locked. The PLL circuit is driven to lock by the compensation charge pump, with or without using the aid of another charge pump. While the PLL is locked, the compensation charge pump may provide a fixed counter-value-proportional compensation current. COPYRIGHT: (C)2007,JPO&INPIT
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