微弱信号采集的前置放大器设计与研究

发布时间：2018-05-29 08:06

本文选题：前置放大器 + 微弱信号采集　；参考：《杭州电子科技大学》2017年硕士论文

【摘要】：随着现代科学技术的发展,微弱信号的采集与分析技术逐渐成熟,促进了国防科技,生物医学,工业应用以及各基础学科领域的技术进步。微弱信号通过各类传感器转换为电学信号,但传感器输出的信号通常微弱且频率较低,需要一个高性能的模拟前端链路来处理信号,它是微弱信号采集系统的核心模块。自然界中的低频微弱信号种类众多,本文将以典型的生物医学信号作为研究对象进行电路设计。本文以有效提取生物医学信号为目的,致力于设计一个低噪声,低功耗和低芯片面积的模拟CMOS前置放大电路。由于生物医学信号因个体差异和采集环境不同会导致其幅度存在较大差异,本文将设计一个电阻式可变增益放大器,利用可变增益放大器增益可调的特性,来针对不同的生物医学信号选用不同的增益实现放大,放大器能够分别实现对脑电信号的100倍放大和神经信号的1000倍放大。为了提高电路的电源电压抑制比,并抑制采样传感器带来的直流漂移电压,本文引进著名的“交流耦合-电容反馈”仪表放大电路,它使用电容和高阻抗的NMOS电阻,产生带通滤波效果,还可以去除低频和高频的噪声。整体的前置放大电路由可变增益放大器和仪表放大器级联而成,本文将分别探讨不同级联架构的性能,并针对幅度在0.5Hz-1kHz的生物医学信号,例如人体的心电信号,采取最适合的仪表放大器级联可变增益放大器的架构,该架构可以实现对信号的1000倍放大,并能达到良好的性能指标。本文提出的模拟前置放大电路工作电压为1V,采用0.18μm CMOS工艺,使用Hspice工具进行仿真,整体电路平均消耗功率为2.9μW,增益约为57.6 dB,共模抑制比约为120 dB,0.5Hz-200 Hz频率范围内的等效输入噪声为1.59μV。
[Abstract]:With the development of modern science and technology, the acquisition and analysis of weak signals is becoming more and more mature, which promotes the progress of defense technology, biomedicine, industrial application and various basic disciplines. The weak signal is converted into electrical signal by various sensors, but the signal output by the sensor is usually weak and the frequency is low. It needs a high performance analog front-end link to process the signal, which is the core module of the weak signal acquisition system. There are many kinds of low frequency weak signals in nature. In order to extract biomedical signals effectively, a low noise, low power and low chip area analog CMOS preamplifier circuit is designed in this paper. Because the amplitude of biomedical signals varies greatly due to individual differences and different acquisition environments, a resistive variable gain amplifier is designed to make use of the adjustable gain characteristics of the variable gain amplifier. The amplifier can amplify the EEG signal by 100 times and the nerve signal by 1000 times respectively. In order to improve the supply voltage rejection ratio of the circuit and suppress the DC drift voltage brought by the sampling sensor, this paper introduces the famous "AC coupling-capacitance feedback" instrument amplifier circuit, which uses the capacitance and the high impedance NMOS resistance. The effect of bandpass filtering is produced, and the noise of low frequency and high frequency can be removed. The whole preamplifier circuit consists of a variable gain amplifier and an instrument amplifier. This paper will discuss the performance of different cascade architectures, and aim at biomedical signals with amplitude in 0.5Hz-1kHz, such as ECG signals of human body. Adopting the most suitable architecture of cascade variable gain amplifier of instrument amplifier, the architecture can amplify the signal 1000 times and achieve good performance. The working voltage of the analog preamplifier circuit is 1V, and 0.18 渭 m CMOS process is adopted. The simulation is carried out by using Hspice tool. The average power consumption of the whole circuit is 2.9 渭 W, the gain is about 57.6 dB, and the common-mode rejection ratio is about 120 dB 0.5 Hz ~ 200 Hz. The equivalent input noise is 1.59 渭 V in the frequency range of 0.5 Hz to 200 Hz.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN722.71

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