A robust frequency compensation scheme for LDO regulators

In the frequency compensation scheme of low drop out (LDO) voltage regulators, a zero generated by the series combination of load capacitor and its electro static resistance (ESR) plays an important role. This frequency compensation tends to be inefficient, as one has to take into consideration a range of specified values for load capacitor and R/sub ESR/, along with their variation with process and temperature. This paper presents a robust frequency compensation scheme that generates a zero internally without relying on RESR of load capacitor. The proposed frequency compensation has better RF noise rejection, low power consumption and improved transient response. The LDO regulator is designed in 0.35/spl mu/m TSMC technology.