| With the development of the technology about biology and the microelectronics, combine them together to solve the problems of the central nervous system signal regeneration after injury has become possible. It has become the hotspot to implant the electronic device into organism which can help damaged body restore the signal transmission function.The design is based on CSMC 0.5um CMOS process to design a single-channel biological signal amplification circuit, which is mainly consists of nerve signal detection circuit, function electrical stimulation circuits and the output buffer circuit and so on. Through RC coupled network connected to the micro-electrodes, the detecting circuit detects the neural signal from the upper neuron by low-noise and high common mode rejection ratio (CMRR) instrument amplifier. Stimulating circuit amplifies the neural signal further by an inverted operational amplifier (OPA). Then the amplified neural signal is sent to stimulate the lower neuron of the damaged nerve through a buffer. It realizes the effectively transmit of neural signal and the function of regeneration. And according to indicators need to be specially designed two operational amplifiers:folded cascode structure of two operational amplifiers and trans-conductance constant-rail input and output operational amplifier.The design of the biological signal amplification circuit is under the supply voltage of ± 2.5V and the chip area is 0.82mm x 0.72mm. Its gain can be adjusted by adjusting the chip resistor.The simulation shows the circuit gain can varies from 58.7 dB to 109dB, and gain-bandwidth can reach 9.284MHz,3dB bandwidth is greater than 9.4kHz and the power is 25.75mW. Output can basically reach rail-to-output, the output level range of rail is-2.49-2.489V and the input common-mode level in the range of-0.97-1.9V.The input offset voltage is very small. The simulation results show that the design can basically meet the design requirements. |
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