Development Of Digital Multi-channel Pulse Heightanalyzer Based On FPGA

Nuclear energy spectrum measurement is very important in nuclear physicsresearch and application of nuclear technology. Multi-channel pulse height analysisis an important method in nuclear energy spectrum measurement. The improvementand development of spectrum measurement method is a focus question for discussionall along in nuclear measure domain. This article comes from major project of thenational "863Program"(Aviation gamma energy spectrum exploration systemresearch and development projects).(No.2006AA06A207).Generally the traditional analysis instruments use the simulated circuit to filter,forming, to enhance the sample of the reoccupy before ADC. Because realized inhardware that will produce a long dead time,and this will cause count rate overload,and reduce energy of resolution. On the other hand logic analysis part is made up bymany separate components and small-scale IC, which over time each deviceperformance variation is not consistent, environmental factor will easily reduce theperformance, increase the instrument in system maintenance difficulty. Simulatormeans more power consumption，more difficult for the portable power supply. Withdevelopment of high speed ADC and FPGAtechnology mature, instrument digital hasbecome inevitable development trend. In recent years the development of foreigndigital spectrometer is already realized commercialization, there are gaps of domesticresearch and application in this aspect. This paper put forward：Development ofdigital multi-channel pulse height analyzer Based On FPGA; Which include thefollowing several parts.(1)In analog amplifier circuit and high-speed ADC circuit AD9235chip use40M sampling rate to convert data, reduce the system the dead time.(2) multi-channel pulse analyzer based on FPGA+MCU architecture, in chipEP2C8T144I8N realize digital signal processing, including trapezoid filter plastic,fight accumulation processing, and peak extraction. This part is the focus ofthe FPGA digitalprocessing application in the trapezoid filtering method, can effectively reducethe noise and influence of ballistic losses.(3) Digital method to deal with the data which be transported to adjust inc8051f310by interrupt mode, then through a serial port send to PC.After instrument design is completed, the main technical indicators are as follows:energy linear correlation coefficient R is0.9995, Differential nonlinearity(DNL) is1.02%, integral nonlinearity (INL) is0.51%; Stable power supply ripple inthe following10mV; Static power consumption2.04W, dynamic power consumption2.14w.