Design of Analog Fuzzy Logic Controllers in CMOS Technologies

Fuzzy logic is a computational paradigm capable of modelling the own uncertainness of human beings. Fuzzy reasoning is nothing else than a fuzzy logic-based formalism for encoding human knowledge or common sense in a numerical framework. Indeed, the mathematical concepts on which fuzzy logic is supported are very easy to understand. In a fuzzy controller, human experience is codified by means of linguistic if-then rules, which compute control actions upon given conditions. fuzzy logic has been applied to problems that are difficult to solve mathematically. One of its main advantages lies in the fact that it offers a straightforward methodology for modelling and controlling non-linear systems, which are difficult to face by means of conventional techniques. Nowadays, real-time applications of fuzzy logic in different domains are being increasingly reported. ASIC-based analogue hardware becomes an interesting solution for these kinds of applications because it benefits from: savings on silicon surface and power consumption, readily accomplished with strict timing constraints and cost-effective production.This book focuses in-depth on the VLSI CMOS implementation and application of programmable analogue fuzzy logic controllers following a mixed-signal philosophy. This is to say, signals are processed in the analogue domain whereas programmability is achieved by means of standard digital memories. This approach highlights the following aspects: the comprehensive study and analysis of the main analogue fuzzy operators; fuzzy membership functions, T-Norm, T-CoNorm and fefuzzifier circuits; the study and development of mixed-signal fuzzy controllers architectures targeting the requirements for different applications; the fabrication and test of full-ended demonstrators; and the partial fabrication and test of a prototype corresponding to a real-time fuzzy logic application in the field of signal processing. Throughout this text, the authors emphasize and demonstrate the powerfulness of fuzzy logic for the synthesis of analogue non-linear systems in a systematic approach. However, beyond the scope of fuzzy logic applications, the analysis of the circuits presented herein is wide-ranging.These circuits can also be employed in different kinds of applications in the field of analogue signal processing such as neural networks, non-linear and linear adaptive filtering, analogue computation, and so forth.