0.025 mJ/image Fast-scan and SNR Enhanced Electrical Impedance Tomography IC for Lung Ventilation Monitoring

Abstract

Energy efficient lung monitoring electrical impedance tomography (EIT) IC is simulated in 180-nm CMOS process. To increase the speed of impedance sensing, fast settling high pass filter (FS-HPF) and fast settling low pass filter (FS-LPF) is proposed to reduce the settling time which takes over 90% of entire EIT data measurement latency. In FS-LPF, voltage-controlled pseudo-resistor is proposed to realize time-varying resistance. To reconstruct the accurate images, adaptive current control (ACC) scheme is implemented for SNR enhancement. Additional SNR improvements are accomplished by averaging the multiple measurements. As a result, image scanning speed of 30-fps is achieved with 0.025 mJ/Image energy efficiency. The simulation results show that ACC can reduce the image FOM error over 80% rather than conventional constant current injection method.