A Necessary and Sufficient Condition of Supply and Threshold Voltages in CMOS Circuits for Minimum Energy Point Operation

Hidetoshi ONODERA

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E100-A    No.12    pp.2764-2775
Publication Date: 2017/12/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E100.A.2764
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
minimum energy point tracking (MEPT),  dynamic voltage and frequency scaling (DVFS),  adaptive body biasing (ABB),  standard-cell based memory (SCM),  

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Scaling supply voltage (VDD) and threshold voltage (Vth) dynamically has a strong impact on energy efficiency of CMOS LSI circuits. Techniques for optimizing VDD and Vth simultaneously under dynamic workloads are thus widely investigated over the past 15 years. In this paper, we refer to the optimum pair of VDD and Vth, which minimizes the energy consumption of a circuit under a specific performance constraint, as a minimum energy point (MEP). Based on the simple transregional models of a CMOS circuit, this paper derives a simple necessary and sufficient condition for the MEP operation. The simple condition helps find the MEP of CMOS circuits. Measurement results using standard-cell based memories (SCMs) fabricated in a 65-nm process technology also validate the condition derived in this paper.