A linearly/electronically controllable high gain VDGA and its applications

Abstract

Since the transconductance gains of an active building block namely voltage differencing gain amplifier (VDGA) is directly proportional to nonlinear (square root) function of external DC bias currents, affecting the narrow range tunability and low transconductance gains. This article aims to introduce a high gain VDGA by using CMOS current squaring circuits biasing in each transconductance cell. It offers high transconductance gains, wide range of tunability, linearity of controllability, larger input voltage range and nearly infinite input impedance. The proposed circuit was designed using a 0.18 µm CMOS transistors technology. The test was performed using PSpice program, it is consistent with the theoretical expectation. The total power consumption is 2.9 mW at ±1.5 V power supply. Even its power consumption is more than about 3 times of their previously proposed VDGAs, the figure of merit (FOM) of the proposed VDGA is much better than that of the previously proposed VDGAs (about 10 times). Additionally, the applications of the proposed VDGA as a capacitance multiplier, current multiplier/divider, summing amplifier, independently/electronically tunable multifunction filter, precision half-wave and full-wave rectifiers are included to insist the workability of the proposed VDGA.