一种应用于微型气体流量计的低噪声信号采集系统

摘要

针对微型气体流量计对微弱信号采集的要求,采用超低偏置电流的放大芯片LMP7721,辅以Guard环保护技术,再加上24位高精度A/D转换器ADS1211,设计了一种超高分辨率、低噪声的弱信号采集系统.通过将数字和模拟部分分开布局,以及合理的电源和地线设计,系统的性能得到了保证.实验表明:采集系统的最小可分辨信号接近0.1mV,噪声RMS值小于50 μV.%Aiming at requirement of micro gas flowmeter on weak signal acquisition, super low offset current amplifier chip LMP7721 with Guard ring protection technology, and 24 bit A/D converter ADS1211 are used in the design. A super-high resolution and low noise weak signal acquisition system is designed. Performance of the system is guaranted, digital and analog part must be laid out separately, and power and ground wires also should be planned reasonably. The experiment shows the least resolved signal is close to 0. 1 mV,and the noise RMS is less than 50 u.V.