A 1-V 2.4-GHz CMOS frequency synthesizer with current-match charge pump

A 1-V 2.4-GHz fully integrated frequency synthesizer for Bluetooth applications is proposed and designed in 0.25-mum CMOS technology. An improved current-match charge pump circuit without the start-up problem is used to reduce the spur level. Moreover, a bandswitching VCO is used to reduce the Kvco and hence the spur level can be further reduced. The prescaler is designed in 1-V supply voltage without the supply-voltage boosting. The circuit is verified by both HSPICE and ADS simulations