A 0.6-V power efficient digital LDO with 99.7% current efficiency utilizing load current aware clock modulation for fast transient response

Abstract

This paper describes a fully integrated, low voltage digital low-dropout voltage (DLDO) regulator for ultra-low power applications with a load current aware clock modulation scheme. The proposed DLDO uses a clock modulation technique that provides a fast transient response during load state transitions. The proposed clock modulation (CM) controls the clock frequency when it senses a sudden load current transition. This eliminates the tradeoff between transient time and power efficiency with a fixed clock frequency. Thus, it minimizes the transient response time and maximizes the power and current efficiency. The proposed DLDO operates at 0.6 V and generates 0.55 V output voltage. A test chip is fabricated using 65-nm CMOS technology and demonstrates the current efficiency of 99.7% with the load current from 10 μA to 200 μA with and the quiescent current of 0.9 μA.