A current-mode piecewise-linear function approximation circuit based on fuzzy-logic

This work describes an analog circuit for function approximation working in current-mode. It implements a piecewise-linear fuzzy system: the membership functions are generated by the daisy-chain connection of identical blocks, resulting in a grid placement of the rules, and programming is achieved by binary encoded digital words representing the consequence of the rules. An approximated analytical model is derived, relating the I/O spread with the bias current variation. The current level allows speed and precision to be traded off for power consumption, while maintaining the same normalized I/O characteristic. The circuit is shown to operate correctly both in strong and weak inversion, with a bias current varying by two orders of magnitude.

[1]  Klaus Schumacher,et al.  Universal low cost controller for electric motors with programmable characteristic curves , 1996 .

[2]  Riccardo Rovatti,et al.  Fuzzy piecewise multilinear and piecewise linear systems as universal approximators in Sobolev norms , 1998, IEEE Trans. Fuzzy Syst..

[3]  Fumio Ueno,et al.  A novel implementation of fuzzy logic controller using new meet operation , 1994, Proceedings of 1994 IEEE 3rd International Fuzzy Systems Conference.

[4]  S. Sanchez-Solano,et al.  Integrated Circuit Implementation of Fuzzy Controllers , 1995, ESSCIRC '95: Twenty-first European Solid-State Circuits Conference.

[5]  M. Castilla,et al.  A synthesis of fuzzy control surfaces in CMOS technology , 1997, Proceedings of 6th International Fuzzy Systems Conference.

[6]  M. J. Patyra,et al.  Analysis and design of CMOS fuzzy logic controller in current mode , 1994, IEEE J. Solid State Circuits.

[7]  G. Geelen,et al.  An inherently linear and compact MOST-only current division technique , 1992 .