便携式心电检测放大电路设计

Design of Amplifier Circuit for Portable Electrocardiogram Monitoring System

目的:为便于日常心电监护,开发了一种便携式心电检测系统,介绍这种便携式心电检测系统中放大电路的设计。方法:该心电放大电路以AD620、OPA4277和TLC2254作为放大电路核心元件,针对心电信号的特殊信号和干扰频率范围,进行了分析,对由电极采集到的心电信号,通过前置放大部分,将微弱的心电信号高保真放大,并通过低通滤波、高通滤波及50 Hz陷波滤除干扰。结果:差模电压增益为1 000,共模抑制比为90 dB,输入阻抗大于10 GΩ,通频带为0.035～110 Hz。结论:系统具有高输入阻抗、高共模抑制比、低噪声、低温漂和高信噪比等优点,而且成本低、体积小、耗电少、携带方便。

Objective To design a portable ECG Monitoring System for the purpose of everyday ECG（electrocardiogram） monitoring, and introduce the design of the amplifier circuit. Methods AD620,OPA4277 and TLC2254 were adopted as the major components of the amplifiers, ECG signal and the frequency range of interference were analyzed. Weak ECG signal collected by the electrodes was high-fidelity amplification through preamp, and then was filtered out the interference using a low-pass filter, a high-pass filter and 50 Hz Notch filter. Results Differential mode voltage gain was 1 000, CMRR （common-mode rejection ratio） was 90 dB, input impedance was more than 10 GΩ, and bandwidth was 0.035-110 Hz. Conclusion The characteristics of the circuit shows in the merits of high input impedance, high CMRR, low noise,less excursion and high SNR （Signal-to-Noise Ratio）. What＇s more, this system has the advantages of low cost, small volume, low-power and being easy to carry.