Cmos Mixed Signal Design of Fuzzy Logic Based Systems

Limits to precision impose limits to the complexity of analog circuits, hence fuzzy analog controllers are usually oriented to fast low-power systems with low medium complexity. This paper presents a strategy to preserve most of the advantages of an analog implementation, while allowing a marked increment in system complexity. A digitally-programmable analogue fuzzy logic controller (FLC) is presented. Input and output signals are processed in the analog domain whereas the parameters of the controller are stored in a built-in digital memory. Design emphasis has been placed on consequents and defuzzifiers. The singleton or zero-order Sugenopsilas method is chosen since it offers a good trade off between simplicity and accuracy. The circuits have been simulated using Tanner tools.