A digital-selected current-mode function generator for analog signal processing applications

A new current-mode function generator circuit is presented, having a much smaller complexity per function with respect to the previous reported similar works. The circuit allows computing an important number of mathematical functions using their n-th order limited polynomial series expansion. The approximation error could be strongly decreased by increasing the number of terms considered in the previous expansion. The selection of the active function is digitally made, the main part of the function generator being common for all the computed functions. The circuit is implemented in 0.35 μm CMOS technology, the SPICE simulations confirming the theoretical estimated results.