Research On Low Voltage And Low Power Design Technology Of LNA For Bioelectric Monitoring

Health Internet of Things(H-Io T)is considered to be an important way to relieve the pressure of aging population on the medical security system.Its principle is to collect the bioelectrical information of human body in real time,transmit the information to the cloud through intelligent devices for big data interconnection,so as to get real-time monitoring,feedback and care.Among them,bioelectrical signal monitoring is the premise of subsequent information transmission,processing,feedback and other process.Low noise amplification is the key process for bioelectrical monitoring.From the perspective of endurance and application flexibility,the whole bio-signal monitoring system is expected to feature very low power.For digital circuits,reducing the power supply voltage can significantly reduce power consumption.However,the design of analog circuits under low voltage is facing many challenges.Considering that the compact system design often requires analog circuits and digital circuits to share same power supply voltage.Therefore,as a typical analog circuit,the low voltage low power design of low noise amplifier(LNA)is a very important research topic.Based on the above background,the specific research work and results of this thesis are as follows:1)The amplitude,frequency and other related characteristics of common bioelectrical signals are studied.According to the application requirements,the performance indicators of LNA are defined.Through the systematic analysis of the existing categories of LNA under low voltage,and compared with the existing low-voltage low-power LNA design technology,the design idea of low-voltage low-power LNA in this thesis is clarified.2)For the application of the bias circuit in LNA,a new low-voltage and low-power all-MOS voltage reference circuit technology is proposed.The subthreshold positive temperature coefficient(PTAT)and negative temperature coefficient(CTAT)current generators are designed with substrate bias temperature compensation technique.After an I/V conversion with temperature compensation,a low-temperature coefficient and low output voltage reference is achieved.The superiority of this proposed bias circuit is verified by the measurement after chip fabrication.3)With the subthreshold design technology and low-voltage mirror current source technology,two kinds of low-voltage and low-power LNA circuits with different structures are designed for ECG,EMG and neural signal monitoring,respectively.The simulation results show that they can meet the application requirements of bioelectrical signal monitoring.The circuit design and chip fabrication in this paper are based on 0.18?m CMOS process.The area of the proposed low voltage subthreshold all-MOS bias circuit is only0.0092 mm~2.The measurement results show that the output reference voltage is 151.9 m V,the average temperature coefficient is 35.7 ppm/?,the power rejection ratio and the linear regulation ratio are-51.8 d B and 0.09%,respectively.With 0.5 V supply voltage,the power consumption of this proposed bias circuit is only 17.6 n W,without any trimming circuit,special process and devices.With 0.5 V supply voltage and dual supply voltage(0.4 V and0.8 V),the simulation results show that these two LNA circuits can achieve 40 d B and 30d B amplification,respectively.Their bandwidth are 0.5 Hz?1k Hz and 0.5 Hz?6.5 k Hz,respectively.Including the bias circuit,the power consumption of these two LNAs are only600 n W and 1.3?W,which can meet the associated bioelectrical signals monitoring.