As illustrated, the filtering and amplifying circuit composed of two parts. Wherein the filter MAXIM MAX267 is an integrated company produced, may constitute a low-pass, band p
ass, high pass, and other methods, the use of flexible, performance is far superior to filter integrated circuit op amp. MAXIMs MAX4471 is a low-power amplifier. MAXIMs MAX9028 is a low-power comparator. Filter circuit MAX267 constitute a band pass filter (0.8 ~ 38Hz signal allowed through), filter out the DC component of the signal and power supply and high-frequency noise and workers skin friction with the cuff frequency interference, and then after MAX4471 for further amplification, SCM get matching voltage signal into ADC2, the AC component of blood pressure monitoring. Meanwhile, the signal passes through a low-power comparator MAX9028 converted into a pulse signal to trigger ADC1 work.