In order to solve the problems of charge sharing, current mismatch, charge injection and clock feedthrough in charge pump of traditional structure, a differential input and singleended output charge pump in adjustable cascode structure is implemented. The circuit is designed in TSMC 0.18μm CMOS RF process. The simulation results with ADS show this charge pump has the advantages of low phase noise, smooth output current, low output voltage harmonic and small switching delay. While the output voltage of the charge pump is varied from 0.7V to 2.4V, the matching of charge and discharge currents is very good.