Design for low current mismatch in the CMOS charge pump

In this study, the charge pump (CP) was designed by gain-boosting amplifiers for lower mismatching. In this design two differential amplifiers were employed to reduce the effect of the channel length modulation in the transistors. This circuit was implemented by the 0.18-μm CMOS technology of TSMC at a power supply of 1.8 V. In our study, the measured mismatch was less than 1% for the output from 0.4 to 1.4 V which is very good for PLL applications.