Low-glitch, high-speed charge-pump circuit for spur minimisation

Abstract

For spur reduction in RF frequency synthesisers, a simple and effective charge-pump circuit is proposed. A prototype frequency synthesiser fabricated on a 0.13 ?m CMOS process, achieves -71.32 dBc at 8.184 MHz offset from a 1.571 GHz carrier with just a second-order loop filter. When the spur level is converted to the input phase error of the PFD, it equals 0.0026 rad.