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.