A transient-enhanced 20μA-Quiescent 200mA-load low-dropout regulator with buffer impedance attenuation

This paper demonstrates a 200mA low-dropout regulator (LDO) for portable applications. Buffer impedance attenuation is developed to realize a single-pole loop response through shunt feedback. The LDO is thus unconditionally stable without using an ESR zero and output undershoots and overshoots are minimized during load transients. Implemented in 0.35 mu m twin-well CMOS, the LDO only dissipates 20 mu A quiescent current. With a 1 mu F output capacitor, the maximum transient-output variation is 54mV with full-load step change of 200mA.