Highly Integrated FPGA-Only Signal Digitization Method Using Single-Ended Memory Interface Input Receivers for...

Area of Science:

• Nuclear Instrumentation
• Medical Imaging Technology
• Digital Signal Processing

Background:

• Traditional Time-of-Flight Positron Emission Tomography (TOF PET) systems require complex and bulky signal digitization components.
• Integrating signal digitization directly onto Field-Programmable Gate Arrays (FPGAs) offers a path towards more compact and efficient data acquisition systems.

Purpose of the Study:

• To develop and evaluate a novel, highly integrated FPGA-only signal digitization method for TOF PET.
• To assess the performance of a digitizer utilizing Single-Ended Memory Interface (SeMI) input receivers for TOF PET applications.

Main Methods:

• Configured FPGA I/O ports with SeMI input receivers, functioning as voltage comparators.
• Implemented a digitizer with 82 energy and 82 timing channels using a 28-nm FPGA, incorporating a 625-ps binary counter and a 10-ps time-to-digital converter (TDC).
• Tested intrinsic characteristics and performance with signals from TOF PET detectors (LYSO crystal coupled with silicon photomultiplier).

Main Results:

• The SeMI input receiver operated as a voltage comparator without undesirable offset voltage.
• Measured standard deviation of time difference between two SeMI input receivers with TDCs was < 14.6 ps RMS.
• Achieved energy resolutions of 7.7% and 7.1%, and a coincidence resolving time of 204 ps FWHM for TOF PET detectors.

Conclusions:

• The proposed FPGA-only digitizer with SeMI input receivers provides a compact, all-in-one data acquisition solution for TOF PET.
• This method enables higher signal density compared to traditional LVDS receivers.
• The integrated system demonstrates high performance suitable for advanced TOF PET imaging.