Digital PWM controller for high-frequency low-power DC-DC switching mode power supply

Abstract

This paper presents a fully synthesizable digital controller for high-frequency low-power DC-DC switching mode power supply (SMPS). Key module of the digital controller is a Hybrid digital pulse-width modulator (DPWM), which takes advantage of Digital Clock Manager (DCM) phase-shift characteristics available in FPGA resource and combines a counter-comparator with multi-bit Delta-Sigma (Δ-Σ) Multi-stAge-noise-SHaping (MASH) modulator. A digital controller which includes the proposed Hybrid Δ-Σ DPWM and a digital PID algorithm is experimentally verified using an FPGA on a high-frequency low-power discrete synchronous buck converter. Experimental results with constant switching frequency up to 4MHz validate the functionality of the proposed digital controller. In addition, the digital controller is implemented in a 0.35 µm standard CMOS.