A multi-stage dual mode digital LDO with fast transient response and adaptive frequency

This paper proposes A Multi-Stage Dual Mode Digital LDO (DDLDO) with Fast Transient Response and Adaptive Frequency. The DDLDO has two types of control loop. One is asynchronous control loop, it is used to improve the transient response under heavy load. Another is synchronous control loop, it uses multiphase Digital Control Oscillator (DCO) to enhance system operation speed, and it has the function of adjusting the clock frequency in the steady state of the system. The proposed DDLDO is implemented in UMC 180nm 1P6M. With VIN=1.2V and 200mV dropout, the proposed LDO can support maximum output current of 50mA with 99.85% current efficiency and settling time is 0.33μs.