Design of a programmable analog CMOS rational-powered membership function generator in current mode approach

This paper presents a novel structure to implement the rational-powered membership functions (RPMF), that are the extended forms of triangular/trapezoidal membership functions and those functions which are generated by applying linguistic hedges. Proposed method is based on the approximation of the function (x^a) by the functions square and square/rooter which are simply implemented in current mode analog approach based on trans-linear principle which leads us to excel in simplicity, high accuracy, and less hardware usage, and therefore lower chip area and less power consumption. Designed circuit were simulated by HSPICE simulator with level 49 parameters (BSIM3v3) and the simulation results show the average power consumption is 800 μwatt, while the RMS error is 1.25%. Finally, layout of the circuit is presented.