A circuit technique to improve phase-locked loop charge pump current matching

A transconductor-capacitor (gm-C) circuit is added to the passive loop filter in a charge-pump phase-locked loop (PLL) with digital phase-frequency detector (PFD). The proposed architecture provides an alternative technique for enhancing the performance of the charge pump without high bandwidth active components. The proposed design also increases the order of the loop, enhancing the rejection of low frequency phase noise sources from within the loop.