Self-Compatible Transistors in GaN-on-Si Technology for High-Voltage Cascodes

This work presents the design and characterization of self-compatible, multistage cascode power transistor "bricks" based on AlGaN/GaN-on-Si technology, enabling modular stacking for high-voltage applications. In contrast to conventional approaches, such as super cascodes or multilevel topologies, the proposed solution is directly driven by stacked transistor segments and eliminates the need for additional components, such as gate control networks or multiple drivers with level shifting. This results in a simpler and more cost-effective configuration. Utilizing the concept of self-compatible building blocks, we demonstrate directly driven, multistage cascode devices, in which all segments share an equal structure. The critical requirement for a highly negative threshold voltage is achieved through gate insulator engineering, while device simulations confirm stable segment potentials and robust voltage sharing. Characterization reveals an ON-resistance of 250 mΩ, a maximum current of 27 A, and OFF-state blocking voltages up to 600 V per brick. The pull-down pin enables direct interconnection of brick devices, demonstrated by a prototype stack with two bricks, which is measured up to 1000 V. This modular and self-compatible approach simplifies voltage scaling and facilitates the practical, scalable implementation of high-voltage power electronic systems with reduced design complexity.