Studies on Hysteresis Characteristics of Fuzzy Muller-C Logic Models

Abstract

The crisp-logic implementation of Muller-C, (CMC) which plays a fundamental role in delay insensitive logic circuits, is a classical, Huffman- type asynchronous network, i.e. a single output combinational logic network with direct feedback. The most typical feature of CMC is the so called logic-hysteresis. The aim of the work presented in this paper was to extend the structure of CMC to a new architecture, which consists of various-norm fuzzy logic elements, and investigate the behaviour from the point of view of hysteresis-like operation. Based on the mathematical formules describing the next-state functions of various norms n-input fuzzy nMuller-C (FMC ) units were modeled by a simple concurrent signal assignment statement, and simulated. The different norm fuzzy-union and intersection functions were implemented in a VHDL package. The simulation results are presented and discussed in the paper. The Zadeh-norm Muller-C does not have hysteresis like behaviour, but it shows an other interesting feature, which is also presented. Last point of the paper contains important advices for implementation of fuzzy Muller-C models with crisp-logic components.