A Fully Integrated High-Efficiency All-NMOS Charge Pump for Wide Input Range Ultra-Low Dropout Regulator

This paper presents an auto-configurable multistage charge pump (CP) designed for a wide input range NMOS low dropout regulator (LDO). The proposed CP built in all-NMOS with multi-gate-boost driver improves the terrible conduct resistance at near-threshold voltage. The CP is also adaptively cascaded, so that the proposed LDO can meet the requirements of wide input range, large loading range and low dropout voltage. With 1.1V input and 420μA loading, the simulation results show the proposed CP reaches 90.5% and 56.1% peak efficiencies for one- and four-stage configurations, respectively. A prototype NMOS LDO with proposed CP has been fabricated in 0.18μm BCD technology. The experimental results show that with 1.1~6.5V input range, the CP can generate a 4.0~10.0V power rail to drive the gate of the power transistor, and a 3.0~5.5V power rail for the control part.