A charge pump for clock management circuit of analog-to-digital converters (ADC) was designed in a 0.13 μm CMOS process. By adding transmission gates between the cascode charge-discharge current source and its bias circuit, the generation of leakage current was effectively suppressed when the charge pump was turned off. By adopting the current source enhanced technique, the impedance of charge-discharge current branch of charge pump was effectively improved, and the influence of channel-length modulation effect was suppressed, so the current matching performance of charge pump was effectively improved. Simulation results showed that the charge-discharge current mismatch was less than 1% with the output voltage varied from 0.13 V to 0.93 V under the condition of 1.2 V power supply voltage and 20 μA output current.