Research On Key Technologies Of Analog Front-end For Bio-signal Acquisition

After the development of the new era,people pay more and more attention to physical health,and it is a new demand in society to obtain physiological information of their own bodies more conveniently and quickly.With the development of various portable intelli-gent medical devices,how to obtain high-quality bioelectrical signals has become the top priority of the entire intelligent medical system.Generally speaking,in a bio-signal acqui-sition system,the analog front end at the front end of the system is usually in the form of an instrumentation amplifier,which dominates the signal quality that can be finally obtained by the entire acquisition system,and an excellent analog front end must have the follow-ing characteristics:high common mode rejection ratio to suppress common mode noise in the acquisition environment,low noise and high input impedance to prevent weak bio-signals from being submerged,low power consumption to ensure long-term acquisition work,etc.The core content of this thesis is various key circuit technologies in the ana-log front-end for bioelectric signal acquisition.The application of these technologies can greatly improve the performance of the analog front-end,including:chopper technology,positive feedback loop,auxiliary input path,signal path ripple attenuation,DC offset sup-pression with feedback loop,T-capacitor network technology,multi-channel improved time division multiplexing technology.In this thesis,a high-performance 8-channel bio-signal instrumentation amplifier is designed and simulated to demonstrate the effect of the above-mentioned key circuit technologies.The amplifier is designed using a standard CMOS 180nm process,and the simulation results show that it is powered by a 1.8V single supply.The current consumption of each channel is 1.38?A,the operating bandwidth is1-1.75k Hz,the gain in the passband is 38d B,the input reference noise is 6.4?V_rms.At50Hz,the input differential mode impedance is 2G?,the input common mode impedance is 18G?,the inherent common mode rejection ratio of the instrumentation amplifier itself is 134d B,and the common mode rejection ratio after the introduction of 1M?||10n F elec-trode impedance mismatch is 97d B,in the multi-channel working mode,after introducing the same electrode impedance mismatch,the common mode rejection ratio is still 97d B.