| 摘要 |
<p>A charge pump (128) in a phase locked loop (100) is enabled only when a loop filter (116) needs to be updated, thereby reducing the power consumption of the charge pump. The charge pump (128) is enabled or disabled in response to an enable signal which is generated by a latch (130). The enable signal is activated by look-ahead signals (PREF, PVAR) which are activated in advance of either a pulse (REF) from a reference signal or a pulse (VAR) from a variable signal so as to allow the charge pump (128) to stabilize before providing charge current to update the loop filter (116). The charge pump (128) is disabled by a reset signal from a phase-frequency detector (126) after the loop filter (116) is updated.</p> |
