SBIR-STTR Award

This project is focused on the development of a new generation of GaN-based transistors with breakdown voltages in excess of 1kV that can be used in the demonstration of power amplifiers operating at 1 GHz with power added efficiencies in excess of 90%. To achieve this performance, this project will develop new approaches to increase the breakdown voltage of GaN high electron mobility transistors, advanced epitaxial structures with minimum current collapse, and improved fabrication technology to reduce the parasitic capacitances of these devices. The device development will be closely coupled to circuit design and simulation to ensure the required record circuit-level performance.

Benefit:
This project aims to demonstrate GaN-based solid state amplifiers with record power added efficiency (>90%) at operating frequencies of 1 GHz. This performance will allow the use of GaN amplifiers in many applications where traveling wave tube amplifiers are used today, including L-band radar systems for both military and civilian applications.

Keywords:
High Electron Mobility Transistor, High Electron Mobility Transistor, GaN, Class-F Amplifier, high voltage switch, power amplifier, power electronics, L-band

The goal of Phase II of this STTR project is to optimize the GaN transistor obtained in Phase I to deliver a 100-W power amplifier with 90% power added efficiency (PAE) at 1 GHz. Emphasis will be put on optimizing output capacitances, improving gate control and further improving epitaxial wafers. We will finalize our design of power amplifier circuit module based on the improved device and our proprietary device models. Device reliability and scalability in output power will be extensively studied. Upon the completion of Phase II base period, we expect to deliver a working prototype of this ultra-high-efficiency PA assembled on a test board. The technology prototype is expected to open up the possibility to replace vacuum-tube-based power amplifiers with solid-state power amplifiers. Such a case will impact a broad range of applications including phase-array radar systems, communication systems, energy transfer modules, and imaging modules in medical equipment. At the end of this project, we will be well positioned to initiate a unique product line that leads the application of solid-state device in ultra-high efficiency power amplifiers for both military and commercial markets.

Benefit:
The proposed technology aims to use solid-state GaN transistors in ultra-high-efficiency power amplifiers, to potentially replace existing high-power vacuum-tube-based power amplifiers. There are tremendous advantages in using the proposed solid-state power amplifiers (SSPA). First of all, a system made of SSPA can be orders of magnitude smaller than a tube-based system. SSPAs can be co-packaged directly with the control electronics, whereas the external circuits of vacuum tubes can be much larger than the tube itself. For example, Figure 1 shows examples of the size comparison between vacuum tubes and packaged GaN power amplifiers. Second, the efficiency of our proposed GaN SSPA technology (>90%) is significantly higher than that of vacuum tube power amplifiers (

Keywords:
Class-F and Inverse-F amplifiers, L-band, high efficiency amplifiers, GaN transistors