A Regulated Multimode Charge Pump with a 0.9–1.4 V Input, a 2.5 V Output, and Adaptive 3×/4× Conversion-Ratio Switching

This paper presents a regulated switched-capacitor (SC) charge pump for low-voltage battery-powered systems. The circuit regulates a 2.5 V output over a wide input range. Its dual-conversion-ratio architecture automatically switches between 3× and 4× modes in response to changes in input voltage and load current to improve conversion efficiency. An adaptive gate-control circuit senses the lower-plate voltage of the second-stage flying capacitor and adjusts power-switch drive strength to limit output ripple. Pulse-skipping modulation (PSM) regulates the output during normal operation. Under a light load, enabling Snooze mode disables the regulation loop, oscillator, and clock drivers to reduce quiescent power. The circuit was designed in a 55 nm CMOS process. Post-layout simulations show a maximum load current of 20 mA, a peak efficiency of 87%, and a Snooze-mode quiescent current below 30 μA. With a 1 μF output capacitor and a 1 mA load, output ripple remains below 25 mV as the input varies from 0.9 to 1.4 V.