According to the low-voltage low-power requirement of the body implatation application of an implantable neural signal regeneration system for treatment of central nerve damages, a constant gm rail-to-rail operational amplifier (op amp) was designed to meet the the need of the intermediate and stimulation stage of the micrcoelectronic neural signal regeneration system. A current switch transconductance control circuit working in the weak inversion region was used as the input stage while a improved feedforward class AB amplifer was used as the output stage. The chip was implemented in the SMIC 0.18 μm 1P6M CMOS process. The simulation and test results show that the circuit can realize the rail-to-rail dynamic range and the constant transconductance. It is suitable for body implantation because the power consumption and the chip area are very small. It can be used for the amplification of weak neural signal in the neural signal regeneration system.%为满足治疗中枢神经损伤的植入式神经信号再生系统的低压低功耗要求,设计了该微电子系统的中间级放大和激励的核心电路——恒跨导轨到轨运算放大器.根据系统满摆幅和低功耗的特点,在电路设计中采用了工作在亚阈值区的电流开关跨导控制电路作为输入级,改进的前馈AB类放大器作为输出级.芯片采用中芯国际0.18μm 1P6MCMOS工艺设计完成.仿真和测试结果表明,芯片实现了满摆幅动态范围,跨导恒定,可用于对探测得到的微弱神经信号的放大和激励,满足神经信号再生系统的要求.此芯片电路功耗和体积都很小,满足生物体植入式器件的要求.
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