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VLSI Design
Volume 15 (2002), Issue 1, Pages 417-426
http://dx.doi.org/10.1080/1065514021000054736

High-performance Multiplexer-based Logic Synthesis Using Pass-transistor Logic

Department of Computer Science and Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan

Received 13 February 2001; Revised 2 March 2001

Copyright © 2002 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

An automatic logic/circuit synthesizer is developed which takes several Boolean functions as input and generates netlist output with basic composing cells from the pass-transistor cell library containing only two types of cells: 2-to-1 multiplexers and inverters. The synthesis procedure first constructs efficient binary decision diagrams (BDDs) for these Boolean functions considering both multi-function sharing and minimum width. Each node in the BDD trees is realized by using a 2-to-1 multiplexer (MUX) of proper driving capability designed pass-transistor logic. The inverters are then inserted all along the MUX paths in order to improve the speed performance and to alleviate the voltage-drop problem. Several methods are proposed to reduce the critical path delay in the multiplexer-chains for generation of faster circuits. Compared to the recently proposed pass-transistor-based top-down design, our synthesizer has better speed and area performance due to the reduced number of cascaded inverters.