A CMOS Dual-mode DC-DC Converter with a Digital Dual-mode Controller

Abstract

This paper describes a CMOS dual-mode DC-DC converter with a digital mode controller, which includes PFM controller and PWM controller. The proposed dual mode controller employs 3-bit control circuit to select a number of counts from a 5-bit digital counter, so that the 3-bit control circuit is capable of adjusting the transient boundary load current between PFM mode and PWM mode. The proposed dual-mode DC-DC converter with a digital dual-mode controller was implemented with a 180 nm 1P/6M BCDMOS process. The measurement results demonstrated the wide range of the input voltage from 2.2 V to 5.0 V with a fixed output voltage of 1.2 V with 3-bit digital capability to control boundary current between PFM mode and PWM mode. The proposed DC-DC converter achieved the peak PFM and PWM power efficiencies of 85% and 91 %, respectively, with an output ripple voltage of 12-32 mV at a switching frequency range of 60 kHz to 2.3 MHz and a load current range of 10 mA to 500 mA.