Fast Transient Dual Mode Low Dropout Regulator for Power Management in SoCs

Abstract

This work presents an Analog-assisted Fast-transient Digital Low Dropout (LDO) regulator for power management systems through an innovative integration of Analog and Digital control loop methodologies. The design contains a charge-pump-based fine loop to provide accurate voltage regulation, attaining an output voltage ripple of merely 0.14 mV. The Digital LDO, on the other hand, indicates steady-state voltage ripples (VRIPP) below 140 μV and functions with a minimum dropout voltage of 20 mV, making it suitable for both noise-sensitive analog circuits and power-efficient digital regulators in system-on-chip (SoC) devices. A key feature of this architecture is the steady-state control system making use of a voltage-to interval converter and a charge pump. This method successfully eliminates VRIPP, giving improved stability in steady-state conditions. The rapid transient response of the regulator is achieved by combining dual-edge-triggered shift registers (DTSR) in the coarse loop, facilitating quick adjustments to abrupt variations in load current (ILOAD). Additionally, the design adds an Analog-assisted (AA) loop, which is necessary for reducing voltage undershoots during load variations, hence providing definitive performance in dynamic settings. Digital LDO regulator is designed in 180-nm CMOS technology, occupying an active area of 0.253 mm². Simulated results demonstrate a line regulation of 8 mV/V and a load regulation of 0.081 mV/mA. This LDO regulator is capable to deliver a maximum load current of 75 mA with a peak current efficiency of 99.93%, rendering it an efficient and feasible option for modern power management needs. This architecture attains rapid transient response and minimum voltage ripples, creating a new standard in voltage regulation. Its distinctive properties make it suitable for complex applications in portable electronics, high-speed processors, and other systems needing stable, efficient, and noise-free power supply. It enhances ripple suppression and transient performance, making itself a state-of-the-art solution for next-generation power management in SoC devices.