Dual-output switched-capacitor DC-DC converter with pseudo-three-phase swap-and-cross control and amplitude modulation mechanism

Abstract

This paper presents an inductorless dual-output switched-capacitor DC-DC converter employing pseudo-three-phase swap-and-cross control (PTPSCC) and an amplitude modulation mechanism (AMM). The AMM circuit scales the amplitudes of the driving signals for the switches according to the loading conditions in order to minimize switching losses. To reduce output ripples, average charge distribution, and improve regulation, the PTPSCC circuit continuously switches power transistors to deliver enough charge to the outputs by keeping at least one flying capacitor connected to each output. The switched capacitor DC-DC converter was implemented in a standard 0.18-mu m 3.3-V CMOS process. Measurements were used to verify that the proposed converter provides dual independently regulated output voltages without cross regulation. The two outputs were regulated at 2.5 and 0.8 V with input ranges of 1.7-2 V. The maximum output loading was 100 mA for both outputs. A power efficiency of 90.5% was achieved at a maximum total output power of 330 mW with a switching frequency of 500 kHz, and a maximum power efficiency of 92.1% was achieved for a total output power of 210 mW. The maximal peak-to-peak output ripple voltages for the two outputs at 100 mA load currents were suppressed to below 26 and 20 mV, respectively.