Design of ACS Architecture Using FinFET and CNTFET Devices for Low-Power Viterbi Decoder Using Asynchronous Techniques for Digital Communication Systems

Abstract

Viterbi algorithm is the most popular algorithm used to decode the convolution code, but its computational complexity increases exponentially with the increasing constraint length due to a large number of Trellis transitions. However, high constraint length is necessary to improve the accuracy of the decoding process for the high rate convolution code. In particular, the Add-Compare-Select (ACS) module of the Viterbi Decoder will have large numbers of trellis states and trellis transitions with increased constraint lengths, which give rise to high hardware complexity and large power consumption. As the performance of the Viterbi decoder mainly depends on its efficient implementation of the ACS module, in the literature, several methods are presented for the implementation of ACS for the Viterbi decoder. The methods based on Precharge Half Buffer (PCHB) and Weak Conditioned Half Buffer, Shannon’s decomposition circuits, body-biased pseudo-NMOS logic and Quasi Delay Insensitive (QDI) timing model performance is analyzed. The methods are implemented using CMOS technology. In this paper, FinFET and CNTFET-based ACS implementation is performed. From the analysis, it has been found that the Carbon Nanotube-based implementation is better in performance when compared to the CMOS and FinFET technology. The proposed QDI model and retiming circuits for ACS block operate above 1[Formula: see text]GHz with high driving current and low power.