Flexible and low-cost FPGA-based multichannel analyzer for handheld measurement devices

This study proposes a flexible, low-cost digital multichannel analyzer (DMCA) based on a field-programmable gate array (FPGA). Digital signal processing modules, including a digital Sallen-Key filter, an energy reconstruction (trapezoidal) filter, a baseline restorer, a timing trigger, and a pulse pile-up rejector, are implemented on FPGA. The proposed DMCA is coupled directly to the detector pre-amplifier without any analog signal conditioning circuit for a simple, compact, and cost-effective hardware design. The parameters of the filtering modules were optimized using MATLAB/Simulink and pulse data digitized using a high-speed analog-to-digital converter. The proposed DMCA also includes a digital gain compensation module to stabilize measured gamma spectra against temperature variation. In addition, software with a user-friendly graphical user interface has been developed for gamma spectrum acquisition and analysis. This prototype DMCA is highly promising for developing handheld radiation measurement devices in terms of performance, cost, and size.