A 4.84mW 30fps dual frequency division multiplexing electrical impedance tomography SoC for lung ventilation monitoring system

Lung ventilation monitoring electrical impedance tomography (EIT) SoC is implemented in 0.18 mu m CMOS technology. A dual frequency division multiplexing (DFDM) method is proposed to extract accurate lung ventilation. To realize the DFDM, the proposed EIT SoC adopts a dual frequency current generator (DFCG) and a dual frequency read-out front-end (DFRF) to process the two frequencies in one channel at once. Consequently, 65.1% of power consumption and 71.5% of area are reduced in each channel. In the DFCG, dynamic element matching (DEM) and adaptive quantization (AQ) techniques are adopted to achieve -46dBc total harmonic distortion. In the DFRF, a weaver demodulator (WD) and a trimmed notch filter combined with low-pass filter (TN-LPF) reduce the settling time of the sensor front-end by 83.3% (0.17ms) to achieve the 30fps real-time operation with 32 electrodes. The proposed EIT SoC is successfully verified by both in-vitro and in-vivo test and achieved 95.35% accuracy.