A single-VDD half-clock-tolerant fine-grained dynamic voltage scaling pipeline

Abstract

We propose a novel dynamic voltage scaling (DVS) pipeline with three significant attributes. First, it features a finegrained DVS which innately attempts to power most of the circuits therein at low voltages, and when the speed is beneath the requirement, to scale up the voltage. Second, it supports fasttransition DVS within one-and-a-half clock duration per operation, and its operation remains error-free during that duration; we define such attribute as half-clock-tolerant. Third, it consists of a single power source (single-VDD) which supports three voltage scales (1.2V, 0.8V and 0.5V) for power/speed tradeoffs, and has standardized 1.2V output to seamlessly interface with other proposed/conventional pipelines. These attributes are achieved due to the embodiment of a DVS power unit, asynchronous building blocks to control/synchronize the operation, a dual-rail critical path to innately detect the completion of the operation, and level shifters to standardize the output voltage. We demonstrate our proposed pipeline by designing a multiplier embodied in a Fast Fourier Transform processor (@65nm CMOS). We show that the multiplier based on our proposed pipeline, on average, is 1.94× more power-efficient than that based on a conventional pipeline