All-digital Hybrid-control Buck Converter for Integrated Voltage Regulator Applications

Abstract

As power-dissipation remains a roadblock to maintaining growth in computational performance, the trend toward increasingly aggressive reliance on Dynamic Voltage and Frequency Scaling (DVFS) by power power management systems, and Integrated Voltage Regulation (IVR) in particular, will continue. As voltage domains continue to shrink, and an increasing number of Voltage Regulators (VRs) are employed within a System-on- Chip (SoC), all-digital buck converters will become increasingly important from a scalability, portability, and system-methodology perspective. In addition to the existing challenges facing VR Modules, IVRs face additional efficiency and transient response challenges. In this paper, we propose a voltage-reference-free all-digital hybrid-control buck converter addressing these challenges through novel techniques for accurate digital derivative measurement for PID control, and fast, all-digital non-linear control for minimizing voltage droop. Simulations in 65nm CMOS demonstrate an 86% efficient, stable operation with fast transient response. A single-phase implementation using package mounted inductor and filter capacitor models achieves a 25mV droop for a 5A load current ramp at 500mA/ns.