A Comprehensive Noise Model for Wideband and High Frame Rate Electrical Impedance Tomography Systems

Clinical applications call for comprehensive performances of electrical impedance tomography (EIT) system, including sufficient signal-to-noise ratio (SNR), high frame-per-second (fps), and wide bandwidth. In this article, thorough analyses of switching noise in an EIT system are presented. The energy of switching noise is split into two parts: spurs and extra quantization noise of analog-to-digital converter (ADC). Based on the characteristics of switching noise, a comprehensive noise model of EIT systems with digital matched filter is proposed. The impacts of switching noise, frame rate, and bandwidth of an EIT system are considered in the noise model. Simulation and experiment conducted in a laboratory-built EIT system are employed to validate the noise model. Test results show that the EIT system can obtain an average SNR greater than 94 dB with a frame rate of 31 frame/s and a bandwidth of 2 MHz and an average SNR greater than 90 dB with a frame rate of 31 frame/s and a bandwidth of 10 MHz, under the guidance of the proposed model. Overall, this work provides a novel and comprehensive noise model by including the impacts of switching noise, frame rate, and bandwidth, which can serve as a guide to improve the comprehensive performance of an EIT system for clinical applications.