The conventional adaptive fuzzy logic controllers are usually too complex for analog circuit implementation.To solve this problem

an on-line adaptive fuzzy logic controller and its application in the control of nonlinear system are studied

whose universe can adaptively change along with the changing of the input variables.Its CMOS analog chip is designed and fabricated.A novel peaky-triangle membership function is proposed to realize the input variable universe part.For the output part of VFLC

the absolute value of the integral of the input variable is used.The other parts are current-mode minimization circuit and a COG (center of gravity) defuzzification circuit.All the above circuits and a whole system were implemented under 0.6μm CMOS standard technology.Their test results show that they fulfill the function of the variable-universe fuzzy logic controller.