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

The design, construction, and implementation of a field‐programmable gate array (FPGA)‐based pulse programmer for pulsed‐electron paramagnetic resonance experiments is described. The FPGA pulse programmer offers advantages in design flexibility and cost over previous pulse programmers, which are based on commercial digital delay generators, logic pattern generators, and application‐specific integrated circuit designs. The FPGA pulse progammer features a novel transition‐based algorithm and command protocol, which 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 one‐dimensional electron spin echo envelope modulation and two‐dimensional hyperfine sublevel correlation (HYSCORE) experiments. The FPGA approach is transferrable to applications in nuclear magnetic resonance (magnetic resonance imaging), and to pulse perturbation and detection bandwidths in spectroscopies up through the optical range. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 43B: 100‐109, 2013