Design and implementation of an FPGA-based timing pulse programmer for pulsed-electron paramagnetic resonance applications

• Type of Material: Article
• Authors: Li Sun, Emory University; Joshua J. Savory, Emory University; Kurt Warncke, Emory University
• Language: English
• Date: 2013-08-01
• Publisher: Wiley
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 Wiley Periodicals, Inc.
• Final Published Version (URL): http://onlinelibrary.wiley.com/doi/10.1002/cmr.b.21240/abstract
• Title of Journal or Parent Work: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering
• ISSN: 1552-5031
• Volume: 43
• Issue: 3
• Start Page: 100
• End Page: 109
• Grant/Funding Information: Research reported in this publication was supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number 5R01 DK054514.
• Keywords: pulsed EPR; pulse programmer; EPR spectroscopy; FPGA; magnetic resonance
• Research Categories: Physics, Electricity and Magnetism; Health Sciences, General; Physics, General

Abstract

The design, construction and implementation of a field-programmable gate array (FPGA) -based pulse programmer for pulsed-electron paramagnetic resonance (EPR) experiments is described. The FPGA pulse programmer offers advantages in design flexibility and cost over previous pulse programmers, that are based on commercial digital delay generators, logic pattern generators, and application-specific integrated circuit (ASIC) designs. The FPGA pulse progammer features a novel transition-based algorithm and command protocol, that is optimized for the timing structure required for most pulsed magnetic resonance experiments. The algorithm was implemented by using a Spartan-6 FPGA (Xilinx), which provides an easily accessible and cost effective solution for FPGA interfacing. An auxiliary board was designed for the FPGA-instrument interface, which buffers the FPGA outputs for increased power consumption and capacitive load requirements. Device specifications include: Nanosecond pulse formation (transition edge rise/fall times, ≤3 ns), low jitter (≤150 ps), large number of channels (16 implemented; 48 available), and long pulse duration (no limit). The hardware and software for the device were designed for facile reconfiguration to match user experimental requirements and constraints. Operation of the device is demonstrated and benchmarked by applications to 1-D electron spin echo envelope modulation (ESEEM) and 2-D hyperfine sublevel correlation (HYSCORE) experiments. The FPGA approach is transferrable to applications in nuclear magnetic resonance (NMR; magnetic resonance imaging, MRI), and to pulse perturbation and detection bandwidths in spectroscopies up through the optical range.