An Accuracy Dynamically Configurable FFT Processor Based on Approximate Computing

Abstract

In order to meet the different requirements of circuit targets in various scenarios, an accuracy configurable fast Fourier transform (FFT) processor based on the concept of approximate circuit is proposed. A configurable approximate butterfly unit which can truncate the carry chain is proposed at the butterfly node and a bit-width configurable multiplier is proposed at the rotation factor multiplication node. MATLAB is adopted to develop an error analysis platform. After analyzing the sensitivity of each butterfly node and rotation factor node to approximate calculations, five calculation modes of the accuracy configurable FFT processor are determined, which can achieve dynamic balance among performance, power consumption, and accuracy. Finally, based on the 180 nm complementary metal oxide semiconductor (CMOS) technology of Taiwan Semiconductor Manufacturing Company (TSMC), the proposed processor is implemented with the standard procedure of ultra-large-scale digital integrated circuits. The performance results are obtained by professional electronic design automation (EDA) tools. Compared with the precise mode, the maximum operating frequency of the processor in the approximate mode is increased by 14.33%, and the power consumption is reduced by 15.61% when the operating frequency is 60 MHz.

Keywords

• approximate circuit
• fast fourier transform (fft)
• accuracy dynamically configurable
• approximate butterfly computation unit
• bit-width configurable