Slides available here!


Speaker:

Prof. Tohru Ishihara, Kyoto University, Japan

Title:

Practical Supply and Threshold Voltage Scaling for Energy Efficient Operation of Microprocessors

Abstract:

Dynamic supply (VDD) and threshold (VTH) voltage scaling has a strong impact on the energy efficiency of microprocessors. Therefore, techniques for optimizing VDD and VTH simultaneously under dynamic workloads are widely investigated over the past 15 years. However, if we divide the region of operating voltage into three, simultaneous tuning of VDD and VTH is not necessarily required. This talk analytically shows the following properties for practical voltage scaling; i) if VDD is sufficiently higher than VTH, tuning only VDD with a fixed VTH maximizes the energy efficiency, ii) if VDD is near-threshold, tuning only VTH with a fixed VDD is sufficient for maximizing the energy efficiency, and iii) if VDD is subthreshold, tuning VDD and/or VTH does not improve energy efficiency. These properties drastically simplify the VDD and VTH scaling, and reduce the cost for providing different VDDs and VTHs. These properties are numerically validated with circuit simulation using a commercial 28 nm process technology model.

Bio:

Tohru Ishihara received his Dr.Eng. degree in computer science from Kyushu University in 2000. For the next three years, he was a Research Associate in the VLSI Design and Education Center, the University of Tokyo. From 2003 to 2005, he was with Fujitsu Laboratories of America as a Research Staff of an Advanced CAD Technology Group. From 2005 to 2011, he was with Kyushu University as an Associate Professor. In April 2011 he joined Kyoto University, where he is currently with the Dept. of Communications and Computer Engineering. His research interests include low-power design methodologies and power management techniques for embedded systems. He has served on program committee of numerous conferences such as CODES+ISSS, ISLPED and so on.



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