| Neural injury and regeneration has been an important topic in neuroscience research. At present, many medical difficulties exist in using medical methods to repair the damaged neural system, especially the damaged central nervous system, with the mutual penetration of neuroscience and semiconductor science or other disciplines, and the smaller and smaller size of CMOS transistor, it is possible to implant a corresponding chip in the nearby of the damaged neural replacing which to complete the neural signal transmission.This article first introduces the theory of neural signal, including the structure and electrical characteristics of neurons; and then introduces the electrodes used in collecting and excitating bioelectric signals, for example, implantable microelectrode and surface electrodes, and compares the probing and exciting neural signal circuit structures. The coral circuit of neural signal bridge integrated circuit system designed in this paper is the CMOS operational amplifier, as the neural signal’s amplitude is very weak, and its randomness is much strong, so we take advantage of the rail-to-rail operational amplifier as the main operational amplifier of the neural signal bridge integrated circuit. This paper design a rail-to-rail high-performanced amplifier based on the theory of analog integrated circuit design flow, layout design, multi project wafer plan, the analog integrated circuit design process 0.35um CMOS process and the CMOS operational amplifier, The post-simulation shows that the amplifier’s open-loop gain is 123.ldB, its unity gain bandwidth is 6.814MHz, its phase margin is 82.21 degrees, its changing range of input transconductance is maintained at 5.5%,the power sourse rejection ratio can reach 121.8dB, and the common mode rejection ratio can reach 125.7dB working in a single supply voltage of 3.3V.Based on the rail-to-rail high-performanced CMOS amplifier, we design a single-channel voltage-excitated neural signal bridge integrated circuit. The circuit comprises the resistance-capacitance coupling network, the pre-instrumentation amplifier, DC compensating circuit, double T traping wave network, and neural function electrical stimulation circuit. As it is easier to match for the capacitances to the resistances, the neural function electrical stimulation circuit uses switch-capacitor amplifier circuit. The post-simulation shows that the total gain is encontrolled by the resistance outside of the chip and changing from 59.7dB-119dB, the 3dB bandwidth is larger than 9.5 kHz, the CMRR is more than 159.8dB, the size of the chip is O.88mm×0.57mm. |
