Data Acquisition System Of CZT Nuclear Detector Based On FPGA

With the development of semiconductor process technology, the processtechnology of making tellurium cadmium zinc (CdZnTe) material is advancing towardsmaturity, CZT materials have superior to many other nuclear detector performance isoutstanding, which make ideal high resolution nuclear detector using CZT materialpossible. In room-temperature nuclear detection field especially in the field of highenergy radiation detection field, CZT nuclear detector is the focus of research in recentone hundred and twenty years. Study of CZT nuclear detector mainly in: the growth ofCZT materials research, the study of CZT electrode and CZT readout circuits system.This paper preliminary studied the CZT nuclear detector readout circuits system, whichinclude two parts mainly: the front analog circuits and digital spectrum processing part.Firstly, the charge-sensitive preamplifier circuit is studied and analysed at frontanalog circuit part. The paper provides a series of simple theoretical analysis and circuitsimulation to charge-sensitive preamplifier with separate component which iscommonly used at home. For reducing the noise of power supply and bias resistors, thepaper present two kinds of circuits to eliminate the noise of power supply and Johnsonnoise of resistance. Circuit simulation and experimental test of the two kinds of circuitshave been given. Then, theoretical analysis，circuit design, circuit simulation and simpleexperimental test of each part of signal disposal circuit are provided in the paper. Thesignal disposal circuit mainly includes pole-zero cancellation, gaussian shape andbaseline recovery circuit. The paper put forward some solutions to solve the problem ofthe signal disposal circuit. Circuit simulation softwares of ORCAD Capture andMultisim10.1have been used in the paper. Finally, PCB circuit board of analog circuitpart has been made and done a simple function test.The main goal of the digital spectrum processing part is to complete the function ofmultichannel analyzer and achieve recorde and output of spectral information. This partalso includes the theory analysis and circuit simulation of analog peak detection anddiscrimination circuit. The circuit simulation based on Multisim10.1. Simplemultichannel analyzer module based on FPGA has been designed using Verilog HDLlanguage in the Quartus II software. The specific function of the module includes peakdetection after A/D conversion, accumulation discriminant, stored and read out of thespectral information, total numerical record and RS232serial port transmission spectroscopy. Timing simulation of each design module is based on software ofModelsim-Altera6.6d, which shows that the function of each module has been realized.Finally, the Gate Level simulation of the whole system proves that it can record andtransfer for nuclear power spectrum.