2、阻抗，高共模抑制比，低漂移，使用uA741即可实现。滤波部分设计成二阶有源带通滤波器，应用电位器以实现频率可调，滤波部分同样考虑使用uA741。功率放大部分主要功能是实现功率放大，实现助听的作用，考虑成本问题，使用LM386。整个电路要求用12V电池供电，加工成PCB电路，同时选用合适机壳，以实现实用性的要求。声音信号清晰，能够实现助听器的作用和频率可调的要求。AbstractThe design consists of 3 part , which is,the microphone amplification section, the filtering section,
3、and the power amplifier section. The microphone amplification section should be a small-signal preamplifier circuit.Design requirements for high input impedance, high common mode rejection ratio, and low drift, which needs uA741 to achieve. The filtering section designs as a second-order ac
4、tive band pass filter, with potentiometer frequency adjustable, the filtering section also uses uA741. The power amplifier part is to achieve power amplification, hearing aid, considering of cost, using the LM386. The entire circuit with a 12V battery-powered, processes into a PCB , the app
5、ropriate choice of chassis, in order to achieve the practical requirements.目录一、设计任务和要求1二、方案选择与论证11.助听器的分类12.耳聋助听器的性能及指标23.总体设计方案3三、单元电路设计与计算说明51.功率放大电路52.电路原理图及仿真结果63.其他单元电路说明74.其他单元电路原理图及仿真结果75.本章小结10四、元器件选择和电路参数计算的说明111．总原理图112．说明113．元器件清单12五、电路原理图13六、电路板图14七、结论与心得15参考文献16一、设计任务和要求1.设计任务（
