BICMOS IMPLEMENTATION OF A FUZZY SYSTEM

BiCMOS circuits which can realise the different mathematical operation s within a fuzzy system are presented in this paper. To maximise the o perating speed of these circuits and increase: the packing density, an analog approach is adopted throughout. The initial focus is on the de sign of circuits to implement fuzzification and intersection. The rema inder of the paper focuses on the hardware implementation of implicati on and defuzzification, thus completing the fuzzy cell library. A majo r objective of this work is to maintain a design strategy which yields simple circuits so as to minimise cell density. Therefore, the circui ts presented are relatively simple but effective with regard to the ma thematical functions that they are required to generate within the cel l. For example, fuzzification is achieved using the current spike deri ved from a CMOS inverter during switching. Both intersection and impli cation are realised using a single MOS transistor operating in the tri ode region. The remaining circuitry consists mainly of an operational amplifier in the summing mode to realise the function of defuzzificati on. The complete fuzzy system is simulated and a transfer characterist ic is presented and discussed. (C) 1998 Elsevier Science Ltd. All righ ts reserved.