Novel pseudo-exponential circuits

In this paper, two voltage-mode circuits that implement the pseudo-exponential function using controllable gain blocks are presented. The gain block of the proposed circuits each utilize a current conveyor and an operational amplifier in a novel manner. They offer the advantages that they are precise, easily implemented in integrated circuit (IC) form and can employ a bank of switched resistors, MOS transistors in triode or transconductors to change their gain according to a control parameter /spl chi/ that is determined by a ratio of resistances. Experimental results using discrete IC components confirm the theory and show the circuits having an output range of approximately 22 dB, with an error of less than 1 dB for x greater than -0.55 and less than 0.63.