A solar-powered 280mV-to-1.2V wide-operating-range IA-32 processor

Abstract

Aggressive power supply scaling into the near-threshold voltage (NTV) region holds great promise for applications with strict energy budgets. In the NTV regime, the supply voltage is at or near the switching voltage (Vr) of the transistors. In this region, energy savings on the order of 5x-10x can be realized. This paper summarizes results from application of NTV techniques to a 32-bit Intel Architecture (IA) core in an effort to quantify and overcome the barriers that have historically relegated ultralow-voltage operation to niche markets. The superscalar IA-32 processor core demonstrates reliable ultra-low voltage operation and energy efficient performance across the wide operating range of 280mV to 1.2V. Starting at 1.2V and 915MHz, core voltage and performance scales down to 280mV and 3MHz, reducing total core power consumption from 737mW to merely 2mW. Minimum energy operation is achieved in near-threshold region with the total energy reaching minima of 170pJ/cycle at 0.45V, validating 4.7X improvement in energy efficiency.