A high CMRR, low power current-mode instrumentation amplifier for biomedical applications

With the advancement of science and technology to change with each passing day in last few years, medical treatment instruments are demanding to develop. Due to CMOS technology, the expensive and large medical instruments will be greatly reduced in both cost and volume. Moreover, the portability and easy-to-use become possible. Recording biomedical signals is one of the challenges in a biomedical electronics detection system, because biomedical signals have very weak amplitude and low frequency, usually of few milli-volts or less and the frequency below 1 KHz. Biomedical signals, such as EEG/ECG signals, are characterized by their low voltage-levels and very low frequencies. Thus, an instrumentation amplifier (IA) must exhibit very low input-referred noise. The used IA must have high input impedance, low output impedance, limited bandwidth and low power consumption. In this paper, we propose a current-mode instrumentation amplifier composed of current conveyors. The features of our current-mode instrumentation amplifier include low power dissipation, low noise, and high CMRR performance suitable for biomedical applications. The low noise combined with high CMRR could effectively suppress noise effects, amplify the physical signals, as well as reflect the real physical status. Circuit simulation results of our study achieved CMRR of 196 dB and low power of 44.98 uW.