Charge recycling on-chip DC-DC conversion for near-threshold operation

Mazumdar, Kaushik; Stan, Mircea R.

doi:10.1109/subvt.2012.6404322

Cited by 5 publications

(11 citation statements)

References 6 publications

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“…Stacked regulation achieves 81%-95% efficiency (depending on imbalance between stacked domains) compared to 81% for nonstacked load of 200 mA for 1.2 V-0.6 V down conversion. Thus it is fair to say, even in the worst case, stacked regulation is comparable to the best case in conventional SC regulation [9].…”

Section: Sensitivity Analysismentioning

confidence: 99%

“…In [8], a shunt regulator was used, and, to balance the different domains, software scheduling was done to distribute the workload at runtime. In our own work, we recycled the imbalance current among the stacked domains using an explicit regulator to improve the efficiency of this technique and maintain the output node within a certain tolerance limit [9]. By using a SC regulator, the achievable efficiency can be more than LDO.…”

Section: Dc-dc Conversion Using Voltage Stackingmentioning

confidence: 99%

“…In [9] we briefly discussed the design rules for this regulator. For a given current imbalance, while the fly-capacitor size determines the amount of charge that can be delivered, the switching frequency sets the output ripple.…”

Section: Power Loss Optimization For Switched Capacitor Circuitmentioning

confidence: 99%

“…As Figure 8a shows, the feedback circuit has considerable impact on efficiency for conventional load, especially at lower current. However stacked load has unique characteristics which are explained below with the help of Figure 1a [9].…”

Section: State Of O/pmentioning

confidence: 99%

“…At an imbalance of 50%, closed-loop SC converter suffers an efficiency loss of 10.8% over an open-loop SC converter. Thus for low power DC-DC conversion, voltage stacking can provide an attractive alternative technique and by removing the additional losses in the feedback circuitry, the efficiency can be improved further [9]. However, for closely matched high power loads, hysteretic feedback can still provide higher efficiency as shown in Figure 9a.…”

Section: State Of O/pmentioning

confidence: 99%

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Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

Mazumdar

Stan

2013

JLPEA

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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%.

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Section: Sensitivity Analysismentioning

confidence: 99%

Section: Dc-dc Conversion Using Voltage Stackingmentioning

confidence: 99%

Section: Power Loss Optimization For Switched Capacitor Circuitmentioning

confidence: 99%

Section: State Of O/pmentioning

confidence: 99%

Section: State Of O/pmentioning

confidence: 99%

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Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

Mazumdar

Stan

2013

JLPEA

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Breaking the 3D IC power delivery wall

Mazumdar

Stan

2012

2012 Conference Record of the Forty Sixth Asilomar Conference on Signals, Systems and Computers (ASILOMAR)

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Several power "walls" that must be overcome in future technologies are the 3D IC power delivery wall and the on chip power regulation efficiency wall. In 3D ICs, power is consumed in the volume of the 3D chip, but can be delivered only to a 2D surface -as the number of layers in a 3D IC becomes larger, the greater the mismatch between 3D consumption and 2D delivery. The efficiency of on-chip regulators, which bounds the overall power efficiency of an IC, is not unique to 3D, but becomes essential due to the volumetric nature of the system. This paper studies voltage stacking of multi-layer heterogeneous 3D systems with distributed DC-to-DC on-chip regulators. The physical layering of 3D IC naturally maps to a voltage stacked solution that overcomes some of the difficulties with voltage stacking in 2D, such as isolating the stacked domains from the substrate. The paper presents a design methodology and optimization strategy for efficient on chip regulation using switch capacitor. Through simulation, we show how voltage stacked clustered layers can help overcome some of the limitations in 3D IC power delivery design.

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A modelling and design approach for push/pull switched capacitor DC-DC converters

Sarafianos

Steyaert

2016

2016 IEEE 17th Workshop on Control and Modeling for Power Electronics (COMPEL)

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This paper presents an extension to the switched capacitor DC-DC converter model when supplying loads stacked vertically. Stacking loads vertically drastically reduces the required size of a DC-DC converter, as it only needs to supply the mismatch current between the loads. Furthermore, when loads are perfectly matched, efficiency is only limited by the power consumption of the control loop, achieving efficiencies close to 100%. The proposed adapted model is extensively discussed, along with system level considerations regarding the required control loop. As a proof of concept, simulations of a transistorlevel DC-DC converter that supplies three vertically stacked loads are shown.

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Charge recycling on-chip DC-DC conversion for near-threshold operation

Cited by 5 publications

References 6 publications

Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

Breaking the 3D IC power delivery wall

A modelling and design approach for push/pull switched capacitor DC-DC converters

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