A 1.24 μ A quiescent current NMOS low dropout regulator with integrated low-power oscillator-driven charge-pump and switched-capacitor pole tracking compensation

Supply regulation using low quiescent current linear regulators helps in extending the battery life of power aware applications with very long standby time. A 1.24 μA quiescent current NMOS low dropout (LDO) that uses a hybrid bias current generator (HBCG) which boosts the bias current dynamically and adaptively to improve the transient response is presented in this paper. A bias-current scalable error amplifier with an on-demand pull-up/pull-down buffer drives the NMOS pass device. The error amplifier is powered with an integrated dynamic frequency charge pump to ensure low dropout voltage. A low-power relaxation oscillator (LPRO) generates the charge pump clocks. A novel switched-capacitor pole tracking (SCPT) compensation scheme is proposed to ensure stability up to maximum load current of 150 mA with a low-ESR 1 μ F output capacitor. Designed in a 0.25 μ m CMOS process, the LDO has an output voltage range of 1-3 V, a dropout voltage of 240 mV, and a core area of 0.11 mm².