Design of High CMRR Instrumentation Amplifier for Biomedical Systems

This paper describes an instrumentation amplifier (INA) with three operational amplifier (op amp) topology, for biomedical applications. To achieve low offset new circuit technique is achieved by adding NMOS transistor and two phase clock scheme with a frequency of 20 KHz. With the unity gain bandwidth of 92 KHz , the open loop gain of this instrumentation amplifier is found to be 50 dB and have common mode rejection ratio (CMRR) of greater than 150 dB .The offset voltage is 1 mV. The instrumentation amplifier is implemented in a 0.18 μm CMOS process in Cadence specter environment. Experimental results show that this instrumentation amplifier can be used in biomedical devices.