A Fully-Differential Low-Noise Instrumentation Amplifier for Electrical Impedance Tomography

Electrical impedance tomography (EIT) is a promising technology for healthcare. It enables patient bedside monitoring, thus establishing an early warning capability. Lung ventilation monitoring is an example of EIT applications. At the core of this system is an instrumentation amplifier needed to detect the small signals at the electrodes attached to the body. This paper proposes a fully-differential low-noise instrumentation amplifier for lung ventilation monitoring. The proposed design is implemented using 0.18μm CMOS TSMC technology and validated using simulations in the Cadence Virtuoso environment. The proposed design achieves a closed-loop gain of 20 dB, a 100 Hz - 200 kHz bandwidth, and a noise floor of 10nV/ Hz at a power consumption of 242 μW. Thanks to its fully differential nature, the proposed design achieves a common-mode rejection ratio (CMRR) of 200. In comparison with prior art, the proposed design achieves improved performance in terms of noise and CMRR.