CMOS current-mode pseudo-exponential function circuit

A current-mode analogue circuit that implements a pseudo-exponential function is proposed. The design of the circuit is based on Taylor´s series approximation, using MOS transistors in the saturation region. The advantage of this circuit is that the output current presents a very low temperature coefficient (TC) and is also immune to the body-effect. Simulation and experimental results show that the circuit offers a maximum output range of /spl sim/30 dB, with an error of less than 1 dB and TC=-233 ppm//spl deg/C.