Switching characteristics of integrated GaN-on-Si half-bridge and driver circuits [article]

Stefan Mönch, Universität Stuttgart
This work examines particularities in the switching characteristics of gallium nitride (GaN) half-bridge and driver circuits, which arise from the integration on a common conductive silicon (Si) substrate, or from the operation of discrete devices on an electrically coupled Si substrate. The supposed advantages of monolithic integrated half-bridges and drivers are promising: The reduced parasitic interconnect inductance improves voltage-switching transitions. The Si carrier allows low-cost and
more » ... arge-scale fabrication. A single integrated IC simplifies the assembly compared to conventional multi-chip power modules. However, the operation of such monolithic GaN-on-Si power circuits also evokes substrate-related effects, especially at elevated operation voltages, which were previously not relevant for single low-side GaN HEMTs. On the one hand, deteriorating effects such as on-resistance increase by negative substrate biasing (back-gating) have to be considered. On the other hand, beneficial effects such as the possibility of decoupling of substrate capacitances can be exploited for reduction of switching energies and consequently increased efficiencies compared to conventional discrete GaN power transistors. Furthermore, even though the monolithic integration of a gate driver with a power transistor reduces the interconnect parasitics between the driver and the transistor, still external interconnects to decoupling capacitors are required. The monolithic integration of half-bridges and drivers thus does not fully eliminate parasitic gate-loop and power-loop inductance. Therefore, advanced assembly technologies such as PCB-embedding of GaN-based power integrated circuits should also be considered in combination with the monolithic circuit integration. First, this work provides a theoretical framework to calculate and compare the effect of substrate-capacitances on application-oriented half-bridge capacitances for different feasible substrate terminations of discrete and monolithic GaN-on-Si half-bridges. It is expla [...]
doi:10.18419/opus-11780 fatcat:py4usfsdzzbstekt427y4dkpni