Pseudo-exponential computational circuit with improved accuracy and frequency response

A new higher-order CMOS current-mode pseudo-exponential circuit will be presented. The advantage of the circuit with respect to the previous reported similar ones is the smaller value of the limited expansion error obtained by using a higher order approximation of the exponential function. The circuit presents the important advantage of the independence of the output current on technological parameters. Due to the strong inversion operation of all MOS transistors and to the current-mode operation of the circuit, the circuit frequency response can be strongly improved. The second-order effects will be taken into account for evaluating the total error of the circuit core, resulting an additional error summed to the error caused by the neglecting of the superior-order terms from the exponential function Taylor series expansion. The circuit area is relatively small due to the exclusively utilization of MOS transistors.