A CMOS CFIA with digitally controlled gain designed for EEG systems

The current feedback instrumentation amplifier (CFIA) designed for EEG detection systems is presented. This CFIA includes two digitally programmable operational transconductance amplifiers (DPOTAs) and a current feedback operational amplifier (CFOA) where the digital control of DPOTA is done using 4-bit current division network (CDN). PSpice simulation results are carried out using 0.25μm IBM CMOS process under ±0.8V supply voltage. The CFIA reaches 126.6dB common mode rejection ratio (CMRR), consumes 695μW, and has 9.4777μV/√Hz input referred noise. The achieved gain is from 22.236dB to 45.386dB. These results make the CFIA suitable for the EEG detection systems.