Abstract: An improved charge-averaging charge pump and the corresponding circuit implementation are presented.The charge-averaging charge pump proposed by Koo is analyzed and a new scheme is proposed.This new scheme decreases power by 1/3 and eliminates the practical defects in the original.Spectre Verilog behavioral simulation results show that the proposed scheme can strongly reduce the energy of spurs.Circuit implementation of this new charge pump for a frequency synthesizer with a fractional division ratio of 1/3 is then presented and multi-level simulation is performed to validate its feasibility at the circuit level.The simulation results show this new scheme outputs a flat voltage curve in a locked state and can thus effectively suppress fraction spurs.

Key words: charge-averaging,  charge pump,  spur