A simple and high performance charge pump based on the self-cascode transistor

摘要

A novel charge pump for phase locked loops application based on the self-cascode (SC) transistor is presented. The proposed charge pump is simple and adds just a few number of transistors to basic charge pump circuit. The SC transistor is self-biased and has high output impedance and lower voltage headroom. Threshold voltage reduction method is used in SC transistor to reduce transistor size, increase the output resistance and help to improve the self-biased structure. The post layout simulation for the charge pump with SC transistor is performed using 180 nm CMOS technology. Based on the Monte Carlo process variation and corner case simulation a 2% current mismatch over the voltage range of 0.35-1.48 V is observed.