A Fast-Transient Low-Dropout Regulator With Current-Efficient Super Transconductance Cell and Dynamic Reference Control

摘要

A fast-transient, current-efficient low-dropout regulator (LDO) with super transconductance cell (STC) is proposed in this paper. By adopting advanced current amplifier (CA) and dynamic biasing (DB) techniques for the error amplifier (EA), the feedback loop bandwidth can be significantly extended without increasing much quiescent power, which reduces output voltage spikes and response time greatly. Moreover, dynamic reference control (DRC) with robust loop stability is embedded in the LDO to adaptively adjust voltage reference during transient so as to further enhance the slew rate of EA, realizing significant enhancement for the transient performances. This circuit has been implemented in a 0.35 mu m CMOS process and occupies an active chip area of 456 x 278 mu m(2). Experimental results show that it is able to provide 100mA load current at 200mV dropout voltage, with current efficiency of 99.88%. The output voltage spike under maximum load current change in 20ns edge time is less than 11.2mV with a 0.054 mu s response time. The power-supply rejection (PSR) at 100kHz is - 75.6dB.