In this paper, a fully programmable membership function generator (MFG) is proposed. This MFG is capable of generating triangular, trapezoidal, and both S-shaped and Z-shaped membership functions simultaneously. Utilizing a differential pair as an analog switch leads to relax the design of fuzzy systems control part. This MFG has the ability of adapting itself with various fuzzy controllers which produce different control voltage ranges. Unlike the available reported literatures, this MFG uses a new analog programmable current mirror (APCM) instead of digitally programmable current mirrors to adjust the slops of membership functions. Extensive time domain simulations have been carried out using Hspice (Level 49) to validate the effective performance of the proposed MFG.