A circuit and a method are provided for reducing power consumption in a phase-locked loop (PLL) by controlling how long the bias current for the charge pump is turned on. In such a circuit, a bias check circuit that indicates when the bias current has stabilized, and a self-adjusting control circuit...http://www.google.com.hk/patents/US5939949?utm_source=gb-gplus-share專利 US5939949 - Self-adjusting startup control for charge pump current source in phase locked loop
