Design and implementation of high-performance data acquisition system in quadrupole mass spectrometer
Xiang Zhong Fang · Journal of Jilin University · 2009
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 the bandwidth on the signal-to-noise ratio(SNR) and the full width at half maximum(FWHM),the suitable gain and bandwidth were selected.Experimental results indicat that in the high-rate scanning,30 kHz bandwidth improves SNR and doesn't effect FWHM and signal intenssity.With the increase of the gain,the SNR increases.As the gain increases from 106 to 108 V/A,the FWHM increases from 0.52 to 0.6.When the gain increases to 109 V/A,the FWHM increases to 2 because of low bandwidth of the preamplifier.In low-rate scanning,as the bandwidlth need is low,109 V/A gain enhances the SNR while mainfaining the FWHM of 0.2.