Power Regulator, also called Voltage Regulator, is an on-chip device which provides suitable power supply for the core from an external high voltage power supply. It is very convenient for a user to supply the chip with only one voltage although the whole chip needs two kinds of different voltage. Present design is a regulator that generates 1.8v voltage from 3.3v power supply. Optimized in GSMC 0.18um 3.3v process, each regulator unit will provide a maximum current of 60mA. In overall, it can provide less than 480mA current for the digital core when eight units are working concurrently.