Fast-transient capacitor-less low-dropout regulator with input current-differencing and dynamic current-boosting

Abstract

Transient response improvement of a capacitor-less low-dropout regulator with input current-differencing is presented in this paper. The Miller compensation technique with series resistance is used to establish the stability and reduce the on-chip capacitor. As a result, the on-chip compensation capacitor of the proposed LDO is reduced to 4 pF which makes it suitable for portable SoC applications. The dynamic current-boosting technique is simultaneously applied to both the input current and the gate of the pass transistor to improve the line and load transient responses of the proposed LDO. The output voltage is regulated at 1 V with a dropout voltage of about 100 mV. The proposed circuit is simulated in TSMC 0.18 μm CMOS technology and its quiescent current is 42 μA. The simulation results of both the line and load transient responses show considerable improvement in the over/undershoot and the settling time of the proposed LDO as well as better transient performance compared to the similar previous works. The output voltage over/undershoot amplitudes of the proposed LDO are obtained 46/100 mV with the settling time of less than 2 μs for the load current changes from 0.1 to 100 mA with 1 µs rise/fall times.