A fast-transient dual loop LDO with high PSR

In this work, the design of a 0.18μm CMOS dual loop capacitor-less low-dropout regulator (LDO) to achieve fast-transient response and good power supple rejection (PSR) is proposed for system-on-chip (SoC) power supply. The proposed LDO has a high slew-rate fast loop for enhancing transient response capability, and the high gain slow loop to improve PSR. Results show that the LDO consumes 100μA quiescent current, delivering a 50mA load current over a 30pF load. The maximum transient output-voltage variation is within 10% of the output voltage with recovery time of less than 81ns with a load step between 500μA and 50mA with 50ns edge times. The PSR is better than 50dB at 1MHz.