高性能四极质谱仪数据采集系统设计与实现

针对四极质谱的谱峰电流信号微弱并且快速变化的特点,设计了复合跨阻抗放大器、四阶低通模拟滤波器和逐次逼近式模数转换器来实现弱电流放大与数据采集系统,用现场可编程阵列逻辑实现了数据采集的实时同步控制和高速大容量数据缓冲等功能。通过分析增益和带宽对信噪比、半峰宽和信号强度等质谱峰参数的影响,选择了合适的增益和带宽。实验结果表明:在快速扫描时,30 kHz带宽满足谱峰带宽需求,提高了信噪比且不影响信号强度;提高增益能提高信噪比,当将增益由106V/A增大到108V/A时,半峰宽从0.52增加到0.6,当增益为109V/A时,由于放大器带宽变窄导致半峰宽增加到2以上。在慢速扫描时带宽需求较小,109V/A增益能提高信噪比和信号强度,并保持半峰宽为0.2。

Design and implementation of high-performance data acquisition system in quadrupole mass spectrometer

A high-prerformance preamplifier and data acquisition system was designed to measure the ultra-low and fast-changing current in the quadrupole mass spectrometer.The system uses a composite transimpedance preamplifier,a 4th-order active low-pass analog filter and a successive approximation analog-to-digital converter.The real-time control and high-speed large-capacity FIFO data buffer of the data acquisition are implemented with the field-programmable gate assay logic.By analyzing the impact of the gain and ...