Design of an analog defuzzifier in CMOS technology

Resumo

The use of intelligent controllers applied to industrial systems has been getting usual, not only in the process control as in the literature. The most utilized control methodology, within the artificial intelligent techniques, is based in fuzzy logic. Fuzzy logic controllers consist of the following modules: fuzzification, decision making and defuzzification. Various defuzzification circuits architecture have been proposed in the literature. The efficacy of a fuzzy logic controller depends very much on defuzzification process. This paper aims to present the project for an analog defuzzifier circuit operating in current-mode to be implemented in CMOS 0.35 AMS. From the hardware point of view, the main characteristics of the proposed defuzzifier circuit are simplified architecture, small chip area and low power-supply voltage. The simulation result of each defuzzifier circuit block will be presented: scaling, addition and division. And also, the output current graphic of the complete circuit, compared with theoretical values. All simulation results have been obtained by the use of SPICE software. The proposed circuit in this work is part of a general-purpose fuzzy microprocessor, and can be applied to many control systems, as for example the control of a DC motor.