DESIGN NOTE: A field-programmable gate-array-based high-resolution pulse programmer

In the work described here, a general-purpose pulse programmer (PP), of very low cost and high resolution, was built using a field-programmable gate array (FPGA). This is a novel application for this device. The FPGA is an integrated circuit which can be programmed to perform a specific task. The pulse programmer built has 16 independent output channels, with resolution of 50 ns, which is also the minimum duration of each event. The basic hardware consists of two chips, an FPGA and the memory, in which the configuration file is stored. The event sequence is sent to the PP through the parallel port of a personal computer, which is controlled using the graphical programming language LabVIEW. This PP was designed to be part of a nuclear magnetic resonance (NMR) spectrometer, used in the study of magnetic metals. The frequency spectra of the pulses were obtained and the results compared with simulated calculations. An NMR spectrum of metallic cobalt was taken, and the 59Co resonance was recorded as a function of frequency after a sequence of two excitation pulses. The results showed good agreement between our spectrum and results from the literature.