The Interface Circuit Design Of Blood Oxygen Saturation Sensor Based On CMOS

In recent years,with the continuous progress of integrated circuit technology and the continuous updating of medical equipment,biomedical chips have become a research hotspot in the field of IC.As an important part of bio-signal detection,CMOS circuit plays an important role in noise reduction,amplification and adjustment of bio-weak signal.Its performance directly determines whether the bio-signal can be extracted accurately or not.Therefore,it is of great significance and value to conduct in-depth research.In this paper,a CMOS interface circuit based on 0.18?m process is designed for optical volume oxygen saturation sensor using Cadence software.It mainly consists of five modules:low noise preamplifier module,high gain preamplifier module,base drift suppression module,bandpass filter module and bandgap reference source module.At1.8V supply voltage,the differential mode gain of the pre-low noise amplifier module is23.4dB,the gain bandwidth is 159.17MHz,the power supply rejection ratio is 82.7dB,the common mode rejection ratio is 92.4dB,the low frequency noise is 662nV/sqrt(Hz);the cut-off frequency of the bandpass filter is 0.5Hz~40Hz,and the gain of the post-high gain amplifier module is 40dB.The system ratio is 127.2dB,the temperature coefficient of bandgap reference source is 2.136ppm/?,the overall power consumption of the circuit is 0.642mW;the layout area is 0.083mm~2,which has been verified by DRC and LVS.By simulation,the performance of the circuit meets the design requirements.Compared with the literature in recent years,the interface circuit in this paper has high gain,high common mode rejection ratio and low input noise.