Thermal management optimization of a GaN SBD limiter via multiphysics co-simulation

Background GaN Schottky barrier diode (SBD) limiters suffer from limiting level drift induced by the self-heating effect under high-power electromagnetic pulse (EMP) irradiation, which severely degrades the power limiting performance and reliability of receiver front-ends. Conventional single-substrate thermal management schemes only cool the bottom layer of the chip, failing to mitigate heat accumulation on the chip surface, and thus cannot effectively suppress the limiting level drift under continuous high-power injection.

Objective This paper aims to quantitatively reveal the internal correlation among the anode temperature rise, on-resistance variation, and limiting level drift of GaN SBD limiters, and to propose a dual-side heat dissipation optimization scheme to restrain thermal-induced limiting level drift.

Methods An electrothermal model of the GaN SBD is established, and a multi-domain co-simulation coupling electromagnetic fields, circuits, and thermal fields is carried out for the limiter. The temperature distribution and electrical characteristics of devices with different substrate materials and surface heat dissipation structures are comparatively analyzed.

Results Simply adopting a high-thermal-conductivity substrate achieves only a limited temperature reduction and fails to eliminate upper-layer heat accumulation. By using a SiC substrate combined with diamond bonding on the chip surface, the anode temperature drops from 651 K to 396 K, and the limiting level is reduced by 2.39 dB (from 26.43 dBm to 24.04 dBm).

Conclusion The proposed multiphysics collaborative simulation framework and dual-side heat dissipation structure can effectively suppress the thermal drift of the limiting level. This design strategy provides an important reference for the engineering design of high-power GaN SBD limiters applied in high-power electromagnetic protection systems.