N13A-T025 TITLE: Gallium Nitride (GaN)-based High Efficiency Switch/Transistor for L-Band RF Power Amplifier Applications.

TECHNOLOGY AREAS: Air Platform, Sensors, Electronics

ACQUISITION PROGRAM: PEO IWS 2.0

OBJECTIVE: Develop a Gallium Nitride (GaN)-based high efficiency switch/transistor and demonstrate a high efficiency (>90% power added efficiency) solid state RF Power amplifier for the replacement of L-band Radar vacuum electronic (VE) tube sources.

DESCRIPTION: Current Navy L-band systems utilize vacuum electronic (VE) sources for high power RF generation. Solid State power amplifiers (SSPA), through power combining, are being considered as replacements for VE sources. Highly efficient, high power SSPA's are required in order to reach improved SWaP and goals that justify the acquisition of replacement sources for the current mature VE sources. The challenge for a SSPA's is to achieve very high electrical to RF conversion efficiencies and simultaneously high output power. The device requirements are a high breakdown voltage (>1000 V) with low on-resistance to develop SSPA's that operate at high RF voltages, minimizing device periphery and output capacitance when compared to current GaN microwave devices, or Silicon and GaAs devices. This enables high efficiency SSPA's that exploit concepts such as switch-mode (Class-D,E,F) operation. A high voltage, fast switching C- to X-band device is required. Amplifiers that achieve 100 W output and greater than 90% efficiency at 1 GHz with 10% bandwidths are desired for current VE replacement concepts.

PHASE I: Provide an initial development effort that demonstrates scientific merit and feasibility of an approach to achieving a high efficiency device for switch-mode RF amplifiers at 1 GHz. The effort will demonstrate a device with a breakdown voltage greater than 1000 V, and operation at 300 volts. Measured device frequency performance shall be sufficient for the realization of various high efficiency RF amplifier topologies. Device geometry should provide scalability in operating current either through periphery or area in order to enable high net output power in an RF amplifier. Device operating parameters should be comparable to known acceptable conditions for reliable Gallium Nitride devices

PHASE II: Demonstrate a 1 GHz RF amplifier with 10% bandwidth, with 100 W output power and 90% power added efficiency, based on the Phase I device. The amplifier will be operating at a minimum supply voltage of 300 Volts. Based on the device characteristics, develop models and predict amplifier maximum operating capabilities assuming device scaling in operating current to maximize amplifier output power while maintaining greater than 90% PAE and 10% bandwidth at 300 volt operation.

PHASE III: Demonstrate the scaled device concepts identified in Phase II that the maximize RF amplifier output power while achieving a minimum of 90% PAE and 10% bandwidth. Design and demonstrate the RF amplifier in a form factor that minimizes cost, size and weight.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial radar and communications transmitters such as cellular base stations would benefit with minor design variations of the device developed in this program to accommodate frequency differences.

REFERENCES:
1. A 97.8% Efficient GaN HEMT Boost Converter With 300-W Output Power at 1 MHz, Yifeng Wu; Jacob-Mitos, M.; Moore, M.L.; Heikman, S., IEEE Electron Device Letters, Vol. 29, No. 8, Aug. 2008 Page(s):824 � 826.

2. 3000-V 4.3-milli-Ohm-cm-squared InAlN/GaN MOSHEMTs With AlGaN Back Barrier, Hyung-Seok Lee; Piedra, D.; Min Sun; Xiang Gao; Shiping Guo; T. Palacios, IEEE Electron Device Letters, Vol. 33, No. 7, July 2012 Page(s): 982 - 984