Translinear programmable analog nonlinear function synthesizer

A new circuit configuration is presented for synthesizing analog nonlinear functions. The proposed circuit is based on approximating the nonlinear functions using rational functions. The terms of the resulting rational functions are realized one-by-one, each in a separate building block, and the required function is the sum of the output currents of these blocks. The weights of the rational-functions are controlled using current sources. The circuit is flexible and can synthesize any nonlinear function, to any degree of accuracy, once its rational-function approximation is obtained. The proposed circuit uses only bipolar transistors and current-sources, and is therefore, very attractive for integration. SPICE simulation results are included.