Low-voltage CCII+ Cells-based Tunable, Variable Gain Instrumentation Amplifier for Sub-Audio Frequency Signal Processing

This paper presents a variable gain instrumentation amplifier (IA) which does not use any passive resistor. It has utilized two-CCII+ cells and active load made of two-shunt connected nMOS transistors which produce a varying active load resistor when activated by adjustable DC voltage in the range of ±0.2 V. This tunable gain IA provides variable gain ranging in 40 dB to 80 dB. The input core of CCII+ cell has used symmetric bulk-driven current mirror OTA with self cascode load and partial positive feedback to ensure enhanced input common mode range (ICMR) and small signal performances even with low-DC voltage supply. The designed IA possess very high common mode rejection ratio (CMRR) and power supply rejection ratio (PSRR).