Design of low power LDO based on high swing rate error amplifier

In this paper, a low-voltage differential Low DropOut regulator (LDO) with low static current is designed. In order to solve the problem of inadequate transient response of traditional LDO under low static current, two common-gate differential transconductance cells are cross-coupled as the error amplifier to improve the swing rate and the body-biased operational amplifier is used to change the threshold voltage of the power transistor to achieve fast switching. At the same time, the dynamic bias is used to offset the circuit to reduce overshoot and undershoot.The circuit is designed by TSMC 0.18 μm Complementary Metal Oxide Semiconductor(CMOS) technology and the core area of the layout is 220 µm×140 µm. The simulation results show that the phase margin of the LDO is 100 degrees under the combination of minimum load current and maximum load capacitance, and the static current consumed is only 849 nA. When the load current is switched from 100 μA to 100 mA within 500 ns, the circuit shows good transient response, in which the overshoot is 220 mV and the undershoot is 225 mV. After calculation, theFigure Of Merit( FOM) value is only 0.198 mV.