A novel high CMRR trans-impedance instrumentation amplifier for biomedical applications

A compact high gain current mode instrumentation amplifier (IA) has been proposed for biomedical imaging applications. Conventional IAs rely on several matching resistors which occupies a lot of silicon area, the input and output common mode voltages are exactly same and the maximum applied signal amplitude is limited by internal node voltage swings. The present proposal eliminates the need for matching resistors by processing signals in the current mode. Hence input amplitudes are no longer limited by the voltage headroom and input and output common-mode voltages can be independent. An amplifier with a differential gain greater than 52 dB and a common mode rejection ratio greater than 120 dB has been implemented in 65 nm CMOS Technology and Post layout simulations were presented. The total circuit occupies 4500 μm 2 silicon area and circuit consumes ~ 260 μA from 1.8 V power supply.