TECHNOLOGY AREAS: Air Platform, Sensors, Electronics

ACQUISITION PROGRAM: PMA 265 F/A-18 Hornet, ACAT I

OBJECTIVE: Develop a GaN power amplifier for the quadrature Linear Amplification Using Non-Linear Component (LINC) architecture in the UHF through L-Band frequency range to support navy aircraft communication systems.

DESCRIPTION: Military aircraft communication systems require high linearity and high efficiency amplifiers to handle non-constant complex waveforms. To meet the growing demands of airborne networking, higher performing power amplifiers are needed to meet the Navy's communication requirements. Recent advances in linear power amplifier architectural design, using LINC, have shown improvements in both linearity and efficiency (size, weight and power)[1]. The quadrature (QUAD) LINC architecture utilizes (Laterally-diffused metal oxide semiconductor) LDMOS transistors. LDMOS transistors, when compared to ideal switches, exhibit a noise floor on the quadrature modulators of -150 dBc/Hz. However a broadband noise floor of -170 dBc/Hz is required to meet the noise requirement of the power amplifier system. Despite the success of LINC, the linearity and efficiency of these devices could further be improved.

Gallium Nitride (GaN) transistors are more advantageous as switching devices for the Class D power amplifiers due to their higher power density, higher efficiency, and improved linearity. GaN device technology today provides up to 100 W devices with 60 V breakdown voltage and ft of several GHz, thereby supporting the mobile high efficiency waveforms in the L-band.

The integration of the GaN (e.g. custom MMICS or comparable devices) will provide improved performance of the QUAD LINC architecture. Key parameters of interest are: linearity, efficiency, duty cycle, weight, dimensions, two-tone intermodulation distortion (IMD), fifth order IMD, broadband noise, spurious emissions, noise power ratio, harmonics, instantaneous bandwidth, stability, and automatic power recovery.

PHASE I: Define the technical requirements for the UHF to L-Band power amplifier. Demonstrate the capability of the power amplifier by using computer simulation, analysis, or experimental results.

PHASE II: Demonstrate the push pull QUAD LINC power amplifier architecture in a laboratory environment. Demonstrate that the architecture will meet the performance objectives.

PHASE III: Develop test plans and procedures to evaluate the Quad LINC power amplifier architecture. Demonstrate the operation of the Quad LINC power amplifier architecture in an Unmanned Aerial Vehicle (UAV) and/or F-18 aircraft operating on an active network.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: New highly efficient linear amplifiers will support all spectrums of communications, from radios to cell phones to wireless networks.

REFERENCES:
1. Hegazi, Gamal M., Chu , Thanh T., and Groshong, Richard A., "Improved LINC Power Transmission Using a Quadrature Outphasing Technique", IEEE IMS 2005.

2. Sundstrom, L., "Spectral sensitivity of LINC transmitters to quadrature modulator misalignments:, Vehicular Technology, IEEE Transactions on Volume 49, Issue 4, July 2000 Page(s):1474 - 1487.

KEYWORDS: Power Amplifier; Communications; Linearity; Efficiency; Solid State; Airborne

TPOC: (301)995-8751
2nd TPOC: (301)342-9094

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