A high efficiency adaptively biased LDO with frequency modulated charge pump for NMOS output stage

Abstract

This paper presents an adaptive biased NMOS LDO which contains an adaptively biased pulse-frequency-modulated (PFM) charge pump to improve efficiency. Compared with conventional architecture, the ground current of the proposed LDO is halved under 3mA load current by regulating the charge pump frequency based on the sensed output current. In addition, the power supply rejection is also improved to 66dB@10kHz due to the relatively stable charge pumped. The proposed LDO achieved 99.995% current efficiency under 1A load. The proposed LDO was built with 0.18µm BCD technology. The simulated line and load regulations were 0.199mV/V and 53nV/mA, respectively.