A Broadband, High Common-Mode Rejection Ratio Instrumentation Amplifier

An operational amplifier based instrumentation amplifier (IA) with a common-mode rejection ratio (CMRR) independent of resistance tolerances is presented in this paper. The CMRR is determined by the operational amplifier characteristics. The IA shows a high CMRR up to 100 kHz. Moreover, since the presented IA operates in the current domain, no large internal voltage swings occur, making it an interesting choice for low-voltage applications in situations where common-mode disturbances may affect the signal processing.