High CMRR and Low Output Offset Current Mode Instrumentation Amplifier for Wearable Ballistocardiography Application

Continuous blood pressure monitoring necessitates the use of small wearable ballistocardiography (BCG) devices. This paper presents the design of a current mode instrumentation amplifier (CMIA) as an analog front-end in BCG applications. The circuit uses a differential implementation of an output current subtraction CMIA to achieve a high common mode rejection ratio (CMRR). In addition, chopper stabilization and a DC servo loop (DSL) are implemented to reduce the output offset and offset drift. The designed circuit achieved a minimum CMRR of 135.46 dB, a maximum output offset of 8.017 μV, and a maximum offset drift of 106.433 nV/°C. This results in a low percentage error for BCG signals at the output. In addition, the CMIA operates using a supply voltage of 1.1V, a gain of 47 dB, and a power consumption of 23.88 μW.