An Integrated GaN Overcurrent Protection Circuit for Power HEMTs Using SenseHEMT

GaN power high-electron-mobility transistors (HEMTs), with their fast switching transients and poor overcurrent tolerance, require overcurrent protection (OCP) circuits that can respond in under
$\text{0.5}\, \mu \text{s}$
. Monolithically integrating digital and analog circuits with GaN power devices is enabled by recent advancements in high-voltage GaN integrationplatforms. Thus, integrated OCP designs can be used to reduce the protection response time, the area penalty, and the assembly complexity. This work presents the first fully integrated, senseHEMT-based GaN OCP integrated circuit (IC) with an adjustable current limit and programmable blanking time, suitable for a wide range of power applications. The IC, implemented on a 200-V GaN-on-Silicon-on-Insulator (GaN-on-SOI) process, contains a power HEMT with a senseHEMT for current sensing, a totem-pole-based gate driver, an analog comparator, and a set of logic circuits to enable high-speed closed-loop OCP. The fabricated design is tested in both a clamped switching setup and a 12–48 V boost converter. The minimum OCP response time is estimated to be 36 ns with
$dI_{D}/dt\geq \text{30}\,\text{A}/\mu \text{s}$
, one of the fastest amongst state-of-the-art OCP circuits for GaN.