| Neurological diseases such as paralysis of limbs and neurodegenerative disease have always been a serious problem which could damage human health.Since the 21st century,engineers have been exploring the treatment of rehabilitation after nerve injury or the neurological diseases in life and science fields.,but the current researches have not really made a substantial breakthrough.Along with the rapid development of microelectronics technology,it is an innovative approach to curing these diseases with using the microelectronic integrated circuit chips since the transmission of neural signal in human body is similar to the transmission of signals in an electronical system.At present,many scientific reseachers have done a lot of reseach on the design of neural signal detecting chips.Altouth the neural signal dection chip has made some progress,it still has a great distance for clinical application.Therefore,there is very important value of application for studying and improving the performance of neural signal detection chips.The microelectronic neural bridge circuits which were designed with discrete components have been successfully applied previously,on the basis of which,this paper has proposed a chopper-stabilized neural recording amplifier system circuit.The entire system includes two operational amplifiers:an amplifier based on the inverter structure and a rail-to-rail input and output operational amplifier,a chopper switching modulation circuit and a DC servo loop circuit.The inverter-based amplifier consists of a complementary CMOS inverter and a common-mode feedback circuit.It can effectively utilize the supply current and achieves a higher power noise factor.The rail-to-rail input and output operational amplifier uses a structure three times current mirror input structure and a class AB output structure to achieve rail-to-rail input and output.The chooper switching structure can effectively modulate low frequency noise and offset voltage to a higher frequency band in order to reduce non-ideal characterisitics with a low pass filter.And on its negative feedback path,adding an integrator circuit as a DC servo-loop to realize a sub-hertz high-pass corner frequency.For the integrator circuit in this system,this paper uses the duty cycle resistor structure in the case of trading off the chip area and the influence of noise.The whole circuit design employs 0.18?m CMOS technology and 1.8V power supply voltage.According to the simulation results,the gain and the low-pass corner frequency of this system is 45.21dB and 30kHz,respectively.This circuit could realize the high-pass corner frequency varies from 0.7Hz to2.2Hz.The system noise of thechopper amplifier is3.035×10-14V2/Hz.The chip area is 530?m×650?m.The power consumption is1.23mW.In summary,simulation results meet all the specifications of the design. |
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