Implementation of real-time digital CR-RCm shaping filter on FPGA for gamma-ray spectroscopy

A novel implementation of a digital CR-RCm shaping filter for gamma-ray spectroscopy is presented in this paper, derived from the digitalization and quantization of the input and output voltage of CR and RC circuits. Compared with the conventional digital CR-RCm shaper, it has a relatively simple structure consuming fewer multipliers and is easy to realize on DSP chips. More importantly, this digital shaper also overcomes the shortcoming of the conventional digital CR-RCm shaper, which lacks the function of pole-zero cancellation (PZC). Experimental data on noise suppression, immunity to ballistic deficit, and energy resolution improvement show that the digital spectroscopy system based on the described shaper achieves the same excellent performance as the analog spectroscopy system from CANBERRA, which therefore provides a new way to realize the shaping of digital signals from radiation detectors, and this carries great significance for engineering applications.