毕业设计心电图仪.doc

PAGE 2 摘要 本简易心电图仪由心电信号采集放大电路、心电信号存储与回放系统、直流稳压电源电路三部分组成。本设计对采集的心电信号进行放大、滤波，最后将其清晰稳定地显示在双踪示波器上。在输出显示的同时能对信号进行存储。当需要回放的时候，单片机系统通过控制D/A转换器将原先存储的心电信号重新循环显示在示波器上。 本设计的核心是前向通道放大器电路的设计。所设计的放大器要求具有高增益、高共模抑制比、低噪声、低漂移，因此在放大电路中采用了高性能的仪表放大器 INA128，提高系统的性能指标要求。 本系统的用途是对心电信号进行检测、存储和回放。由于心电信号为弱信号，因此本系统对抗干扰和信号处理能力有较高的要求。方案论证主要集中在数据采集和信号的放大部分。 关键词：OPA37，低功耗、高性能的仪表放大器—INA128, 运算放大器LM741,差动放大,50Hz陷波,0—100Hz低通滤波。 Abstract This simple electrocardiograph consists of the electrocardiosignal gathering and amplifying circuit, the electrocardiosignal memory and replay system, and the direct current voltage-stabilized power circuit. This design carries on the enlargement, the filter to the collected electrocardiosignal, and then demonstrates it on the dual trace oscilloscope clearly and stably. When output the display, can accumulate the signal. When the playback is needed, the single-chip microcomputer recycle and display the stored electrocardiosignal on the oscilloscope by the Digital to Analog. The core of the design is the forward channel amplifier circuit, which requires high gain, high ratio of common mode rejection, low noise, low excursion. Therefore, high quality instrumentation amplifier INA128 is adopted in the amplifier circuit to boost the performance of the system. The purpose of this system is to examine, store and playback the electrocardiosignal. Since the electrocardiosignal is weak signal, this system requires high capability of anti interference and signal processing. The demonstration of the research focuses on the process of data collecting and signal amplification. Key words: OPA37, low power dissipation, instrument amplifier with high accuracy --INA128, Operational amplifier LM741, differential amplification, 50Hz falls the wave,0--100Hz low pass filter. 目录 1绪论5 2正文6 方案分析与论证6 2.1.1 数据采集6 2.1.2 心电信号处理部分7 2.2 系统设计方案及实现方框图9 2.3 电路设计与参数计算10 2.3.1 差动输入放大电路10 2.3.2 加法器电路10 2.3.3 带阻电路（陷波电路）12 2.3.4 低通滤波电路1 2.3.5 精密放大调整电路14 2.3.6 元器件15 2.3.7 直流稳压电源的设计16 心电图仪