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J. Low Power Electron. Appl. 2013, 3(3), 250-266; doi:10.3390/jlpea3030250
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Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

*  and
Charles. L. Brown Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA 22904, USA
* Author to whom correspondence should be addressed.
Received: 6 January 2013 / Revised: 5 July 2013 / Accepted: 9 July 2013 / Published: 29 July 2013
(This article belongs to the Special Issue Selected Papers from SubVt 2012 Conference)
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Abstract

The increasing popularity of DVFS (dynamic voltage frequency scaling) schemes for portable low power applications demands highly efficient on-chip DC-DC converters. The primary aim of this work is to enable increased efficiency of on-chip DC-DC conversion for near-threshold operation of multicore chips. The idea is to supply nominal (high) off-chip voltage to the cores which are then “voltage-stacked” to generate the near-threshold (low) voltages based on Kirchhoff’s voltage law through charge recycling. However, the effectiveness of this implicit down-conversion is affected by the current imbalance among the cores. The paper presents a design methodology and optimization strategy for highly efficient charge recycling on-chip regulation using a push-pull switched capacitor (SC) circuit. A dual-boundary hysteretic feedback control circuit has been designed for stacked loads. A stacked-voltage domain with its self-regulation capability combined with a SC converter has shown average efficiency of 78%–93% for 2:1 down-conversion with ILoad (max) of 200 mA and workload imbalance varying from 0–100%.
Keywords: voltage stacking; charge recycling; DC-DC converter; switched capacitor; energy efficiency; near-threshold; hysteresis feedback; ripple; phase interleaving voltage stacking; charge recycling; DC-DC converter; switched capacitor; energy efficiency; near-threshold; hysteresis feedback; ripple; phase interleaving
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Mazumdar, K.; Stan, M.R. Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator. J. Low Power Electron. Appl. 2013, 3, 250-266.

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J. Low Power Electron. Appl. EISSN 2079-9268 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert