Design Of Amplifier For Electromyographic Signal Detection

According to relevant data,our country has more than 20 million of limb paraplegia patients,including no less than 2 million patients with paraplegia or quadriplegia caused by spinal cord injury.Patients' self-care abilities are greatly impacted and even lost,thus extremely lower their life qualities.By combining micro-electronic technology and nervous system theory via collecting surface electromyography(SEMG)signals from normal human limbs,the whole design generates functional electrical stimulation for paralyzed limbs.As a consequences,the paralyzed limbs coordination and motion function reconstruction can be successfully realized.Surface electromyographic signal acquisition and amplification are very important for the whole neural signal extracting system.This thesis mainly studies the design of surface electromyographic signal amplifier circuit.The front end is a two-stage cascade filter architecture,which separately analyzes the noise and the signal swing.The method based on gm/id is utilized to design each stage of a two-stage operational transconductance amplifier(OTA)respectively.For the frequency selective,its functionality is achieved by using active transistor resistance,while its accuracy is realized by adjusting the grid electrode voltage of MOSFET to control the resistance ratio.The whole framework employs TSMC 0.18-?m CMOS technology and 1.8-V power supply voltage.According to the imitation results,the gain of front end is 60 dB,realizing the frequency-selection for signals between 50 Hz and 1500 Hz.The power consumption is 7.2 ?W.The integrated noise is 2.03 ?Vrms.in the range of 50 Hz to 1000 Hz,resulting in an efficiency noise factor(NEF)of 4.48,the output voltage swing is ±0.92 V,and the whole chip size is 2mm x 3mm.According to the simulation results,the whole front end can detect the weak surface electromyographic signal effectively,establishing a solid foundation for the following signal digital processing and transmission,as well as accumulating experience for transition from discrete components design to microelectronic construction.