A 10 W On-Chip Switched Capacitor Voltage Regulator with Feedforward Regulation Capability for Granular Microprocessor Power Delivery

Abstract

Granular power delivery with per-core regulation for microprocessor power delivery has the potential to significantly improve the energy efficiency of future data centers. On-chip switched capacitor converters can enable such granular power delivery with per-core regulation given a high efficiency, high power density, fast response time, and high output power converter design. This paper details the implementation of an on-chip switched capacitor voltage regulator in a 32 n m SOI CMOS technology with deep trench capacitors. A novel feedforward control for reconfigurable switched capacitor converters is presented. The feedforward control reduces the output voltage droop following a transient load step. This leads to a reduced minimum microprocessor supply voltage, thereby reducing the overall power consumption of the microprocessor. The implemented on-chip switched capacitor voltage regulator provides a 0.7-1.1 V output voltage from 1.8 V input. It achieves a 85.1% maximum efficiency at 3.2 W/mm2 power density, a subnanosecond response time with improved minimum supply voltage capability, and a maximum output power of 10 W. For an output voltage of 850 m\V, the feedforward control reduces the required voltage overhead by 60 m\V for a transient load step from 10% to 100% of the nominal load. This can reduce the overall power consumption of the microprocessor by 7%.