Characterization of SenseGaN Current-Mirroring for Power GaN with the Virtual Grounding in a Boost Converter Mehrdad Biglarbegian and Babak Parkhideh Electrical and Computer Engineering Department Energy Production and Infrastructure Center (EPIC) University of North Carolina at Charlotte Charlotte, USA Email: {mbiglarb, bparkhideh}@uncc.edu Abstract—This paper presents an implementation of the SenseGaN current sensing technique using Gallium Nitride (GaN) transistors as representative of Wide Bandgap (WBG) semiconductors. For effective feedback control, fast over-current protection, and diagnostics-prognostics developments, precise current measurement becomes more crucial. While the integra- tion and miniaturization of power semiconductors are getting more feasible to operate at higher current as well as switching frequency, most of the available current measurement techniques have some technical challenges such as bandwidth limitations, higher power dissipation, and sensitivity variations. SenseGaN technique is along with the integration of semiconductors to monitor the power module current without significant effects on power stage performance and opens a new era for smart devices in future power electronics; however, implementation of this method in practice, has some difficulties that needs to be addressed for careful design consideration. This paper verifies the concept in WBG-based power converters with Spice simulations and mathematical analysis. Finally, a prototype using power 650V-GaN is successfully tested at 150kHz. Index Terms—current-mirroring, current measurement, GaN boost converter, SenseFET, SenseGaN, wide bandgap semicon- ductors, virtual grounding. I. I NTRODUCTION To enhance the performance of switching converters along with improving their efficiency in power electronics appli- cations, a need for higher switching frequency is inevitable. Thanks to the development of Wide Bandgap (WBG) semi- conductors like Silicon Carbide (SiC) and Gallium Nitride (GaN), by knowing hardware difficulties for implementa- tion of high switching frequency/high-current converters to overcome layout issues, electromagnetic interfaces, thermal dissipation management, and passive component challenges, finding alternative solutions for current information is impor- tant [1], [2]. Accurate current sensing methods are among the major steps toward the WBG power converters, bringing multiple opportunities such as effective protection, control, loss calculation, and prognostics techniques [3]. Traditional resistive based methods such Shunt and R ds(on) (drain-source resistance during ON time) monitoring, due to their high loss, and temperature variation dependency, have some fundamental challenges, especially in high frequency converters [4]. In modern research of current measurements, (Hall Effect, Induction-based transducers, Rogowski coil, and Magnetore- sistance (MR) sensors) are now more focused on the investiga- tion of alternative isolated approaches for measuring the high frequency current accurately [5]. Although significant progress has been observed in recent years with the development of these sensors, they are typically limited to effective bandwidth (< 1MHz). High current MR-based sensors have superior performance at the higher frequency, but due to their relatively high costs, they have not fully developed in most of the commercial products [6]. Therefore, with significant efforts in pushing the frequency and power in WBG semiconductors (especially GaN), novel sampling techniques can still provide useful current information. In this paper, we target develop- ment a discrete design of current mirroring method to monitor the current of an active switch in boost converter at 150kHz with GaN. The current mirroring technique can be used for monitoring the power device current practically in a loss-less manner com- pared to shunt resistor method. In power electronics, current mirroring is commercialized and often known as the SenseFET approach [7]–[10]. In this approach, two Silicon-Metal Oxide Semiconductor Field Effect Transistor (Si-MOSFET)s with different resistances are connected in parallel. The one with higher resistance carries much smaller current, yet can repre- sent the current in the main branch with proportion [11]–[14]. Recently, this approach has been demonstrated for SiC and GaN devices integrated with Si MOSFET [15], [16]. However, this technique is typically non-isolated and hence, applicable for grounded devices where the common mode voltage is higher than 30V. To the best of the authors knowledge, no prior work has been published to sense the active current of Power GaN transistors using this technique. We called this technique as SenseGaN that current monitoring can be effectively used in many common converter topologies, where the active device is connected to ground; however, this method has some challenges like matching issue, temperature dependency, non- isolation limitations, which will be going to be addressed. The paper is organized into four main sections: In Section II, the methodology current monitoring with SenseGaN is described,