关键词: 锁相环, 电荷泵锁相环, 锁定时间, 频率比较

Abstract: Taking a wide frequency range charge pump phase locked loop(CPPLL) for field programmable gate array chip as an example, this paper introduces a method to reduce the power on lock time by adding a simple auxiliary circuit. This method adds a precharge circuit to the traditional charge pump phase locked loop, which can greatly reduce the time of V_CTRL voltage rising. In addition, a frequency comparison circuit is added to divide the wide frequency range into several narrow frequency intervals, and the center frequency of the narrow frequency range is used as the judging frequency to turn off the precharge current, so that the power on lock time of wide frequency range phase locked loop can be balanced without affecting the normal function of phase locked loop. In this case, based on 28 nm process, after spectre simulation, when the frequency of phase locked loop with auxiliary circuit is 800-1600 MHz, the power on lock time is only 1.68-2.29 μs.

Key words: phaselockedloop, chargepumpphaselockedloop, locktime, frequencycomparison