Architecture and IC implementation of a digital VRM controller

This paper develops the architecture of a digital PWM controller for application in multiphase voltage regulation modules (VRMs). In this context, passive current sharing and VRM transient response with nonzero controller delay are analyzed. A scheme for sensing a combination of the VRM output voltage and output current with a single low-resolution window analog-to-digital converter (ADC) is proposed. The architecture and IC implementation of a digital PWM (DPWM) generation module, using a ring-oscillator-multiplexer scheme, is discussed. Experimental results from a prototype VRM and a partial controller IC implementation are presented. Index Terms--Analog-digital conversion, current sharing, digital control, digital modulation, inductance, integrated circuits, power conversion, pulse-width modulation, ring oscillators, transient analysis, voltage control.