Research On A Low-power Pulse Oximeter IC For Wearable Medical Devices

Human attach more significance to health condition as the living standard increases.Wearable devices experience rapid evolution at the same time,being applied to customer electronics,medical equipment,smart clothing,etc.Wearable devices which cater to human health,detect and prevent various illnesses commonly combine information technology with biology and medical science via semi-conductors,integrated circuits,and embedded circuits,leading to progress in family practice,thus having great significance to society.The blood oxygen pulse signal capture analog front end is a significant segment which connects physiological signal with signal processing and analyzing,as well as an indispensable part of signal capture.This essay researches the design of blood oxygen pulse CMOS analog front end capture chip based on how to extract blood oxygen pulse signal efficiently in order to calculate blood oxygen saturation.The paper proposed a low-power consumption blood oxygen pulse analog-front-end chip circuit via research on detecting principles of blood oxygen saturation,based on equation of blood oxygen saturation.The analog front end mainly consists of LED driver circuit,trans-impedance amplifier,sampling/holding circuit,programmable gain amplifier,high-pass filter and low-pass filter,and power management circuit.The trans-impedance amplifier adopts chopper technique,decreasing flicker noise and input offset voltage effectively.The chip has been fabricated in SMIC 0.18-?m CMOS technology,with the power voltage 3.3V,reference voltage 1.2V,where the programmable gain amplifier has 3 magnification factors in total----20,50,and 126.The low frequency cutoff and high frequency cutoff of the chip are 0.5Hz and 30 Hz respectively.The quiescent dissipation and noise of the chip are 264?W and 23pA/sqrt(Hz)respectively,satisfying the request on the whole.