A PPG Readout Integrated With RPTT Estimation in Analog For Blood Pressure Measurement

This study proposed a Photoplethysmography (PPG) readout system to estimate the reflective pulse transit time (RPTT) in analog domain for the blood pressure measurement. The proposed photodetector readout consists of a sensing circuit, an amplification circuit, and peak-sensing circuits. The designed circuit is fabricated by TSMC
$0.18\mu \mathrm{m}$
1P6M 1.8V mixed-signal CMOS process. The measurement results show that the design chip consume
$50\mu \mathrm{W}$
and the measured dynamic range is 100 dB. Experimental verification shows that the obtained RPTT from the designed chip is 99.9% correlated with the RPTT obtained after the pre-signal processing of the PPG signal and the measured average difference in RPTT measurement is 15.73 msec. The obtained performance in terms of SBP and DBP shows that the accuracy satisfies the requirement of the AAMI under
$\pm 8$
mmHg.