Design of a Low Quiescent Current Linear Regulator with Wide Input Voltage Range

This paper presents a low-dropout linear regulator (LDO) with an input voltage range of $2 \sim 20 \mathrm{~V}$ and a quiescent current of $2.18 \mu \mathrm{~A}$. A reference voltage lower than that of a conventional bandgap reference is generated by the error amplifier, thereby reducing the quiescent current. A Schottky diode is used as the forward bias between the source terminal and the bulk terminal of the LDO’s high-voltage power transistor to reduce the dropout voltage and achieve a larger load current. Loop stability is achieved in the error amplifier using fixed-zero compensation with an output capacitor. This design, implemented and verified in a 180 nm process, demonstrates a load regulation of $0.018 \mathrm{mV} / \mathrm{mA}$ and a line regulation of $0.032 \mathrm{mV} / \mathrm{V}$. Under load transients between 1 mA and 300 mA, the output exhibits overshoot and undershoot voltages of 96 mV and 58 mV respectively.