CMRR Enhancement in Instrumentation Amplifiers Using an Algorithmic Approach With Dynamic Analog Signal Processing

An algorithmic instrumentation amplifier (INA) with dynamic analog signal processing (DASP) is presented in this article. The proposed approach is based on any basic INA (BINA) subjected to a simple algorithmic operation performed by DASP. The resulting common-mode rejection ratio (CMRR) equals double squared CMRR value of the BINA, with no need for any additional matching. The prototype has been made in a discrete technique with a single supply voltage of 2.7 V. The voltage-mode INA(VMIA) with two operational amplifiers (OAs) has been used as the BINA. The measurements have been performed for six different clock pulse frequencies ranging from 30 to 80 kHz with a step of 10 kHz used in the DASP. The resulting CMRR of 90.03, 80.35, 66.48, and 53.15 dB are achieved starting from a poor CMRR of 42.52, 36.80, 30.09, and 23.76 dB of the BINA, respectively, confirming the proposed CMRR enhancement model
$2\times $
CMRR [dB] +6 dB.