Flexible fuzzy controllers using mixed-signal current-mode techniques

The architecture and required building blocks of CMOS fuzzy chips capable of performing as adaptive fuzzy controllers are described in this paper. The building blocks are designed with mixed-signal current-mode cells that contain low-resolution A/D and D/A converters based on current mirrors. These cells provide the chip with analog or digital programmability and long-term local storage. They also perform as computing elements of the fuzzy inference engine that calculate the output signal in either analog or digital format thus easing communication of the chip with digital processing environments and analog actuators. Experimental results of a 9-rule controller prototype integrated in a 2.4-mu m CMOS process are included. It has a digital interface to program the antecedents and consequents and a mixed-signal output interface.