GaN Based High Strength Magnetic Field Pulser

Abstract

Magnetic field pulser generates magnetic field by driving current through an inductor. These pulsers have numerous applications based on the output magnetic field intensity and switching time. For communication systems, the pulser is central for an all-optical switching platform employing the theory of Faraday rotation [1]. In medical field, the pulser is used to perform transcranial magnetic stimulation to provide safer, noninvasive treatment for certain mental disorders [2]. Another application area is portable magnetic resonance systems where the pulser initiates magnetic resonance [3]. These are just some of the many fields where magnetic field pulsers have found applicability over the years. Recent developments in transistor technologies have enabled production of transistors with higher power and superfast switching. Among these is the introduction of gallium nitride (GaN) based transistors. Compared to silicon-based transistors, GaN transistors have higher electron mobility, a property which allows smaller size for a given on-resistance and breakdown voltage. GaN transistor also offers high drain current and extremely fast switching speed [4]. These are all desirable properties for a switch in the magnetic field pulser design. This investigation will explore the application of GaN transistor in a pulser design. Based on the advantages of GaN transistor, the investigation looks towards creating a pulser capable of producing magnetic field of 500 Gauss with a rise/fall time of less than 500 nanoseconds. This investigation will surpass findings from prior studies to build a pulser targeted for magneto-optic switching [5] applications. A preliminary result as seen in Figure 1 shows that at the same maximum current level, the GaN transistor displays steeper rise and fall when compared to a Si transistor. This result further highlights the potential of GaN transistor as the switching device where rapid switching is preferable.