Charge-pump circuit for a phase-locked loop.

摘要

The present invention discloses a low order charge-pump filter operable with a single variable current source. The integrating capacitor of the charge-pump is connected in an H-bridge switching configuration with four switches that are operable to control the current source to supply current to a first node of the capacitor or to a second node of the capacitor or to bypass a capacitor, depending on the state of operation of the charge-pump. The charge-pump filter disclosed is particularly useful for providing the low order response for a phase detector in a phase-locked loop.