Performance Analysis of BiMOS Differential Pair with Active Load, Wilson and Widlar Current Mirrors, and Diode Connected Topology

The MOSFET (Metal Oxide Field Effect Transistor) is one of the most widely used semiconductor devices in analog and digital circuits for amplification and switching. It is a highly popular power de vice used in power electronics. The important advantages of MOSFET include higher efficiency at lower operating voltages; there is no gate current resulting in high input impedance enhancing its switching speeds. A differential amplifier is a direct coupled amplifier that amplifies the difference between the two input signals arriving at its input and suppresses the common voltage between the two inputs. The important parameter that determines the performance of a differential amplifier is its CMRR which determines the capability of it to amplify the differential mode signal and cancel the common mode signal i.e. noise. To improve the CMRR, the resistor R
E
is replaced by an active load i.e. the current mirror circuit. In this paper, the performance of MOSFET differential amplifier (BiMOS Differential pair) is evaluated using Active MOSFET Load, Wilson Current Mirror and Widlar Current Mirror Circuits. The results of the implementation show that the highest CMRR (31.48 dB) is obtained by using the Diode Connected Topology.