High Linearity-High Efficiency Power Amplifiers Based on Digital Signal Processing Techniques and Wide Bandgap Devices

The goal of this project is the development of effective signal processing and circuits for high power amplifiers and transmitter modules for DoD wireless communication airborne and ground systems. Future base stations require wide bandwidth, high power, high voltage, wide dynamic range, excellent linearity, and high power efficiency. This research is critical to airborne and ground base station applications used for both mobile voice communication links and higher data rate multi-media mobile data communication links. Such systems have high bandwidth efficiency stemming from complex modulation and wide spreading bandwidth, but as a consequence must employ high dynamic range, high bandwidth amplifiers. The amplifiers must also have low power consumption, which dictates operation in saturation for peak efficiency. These requirements oppose each other, and require advanced approaches to realize improved performance.BENEFITS: This research has strategic relevance for today's wireless communication industry. In order to insure electromagnetic compatibility of the shared radio spectrum, the DoD must enforce strict limitations on both RF power and RF bandwidth. The military is then forced to make maximum use of the permitted power and spectrum for capacity, coverage, and quality of service. Hence, high linearity with complex modulation schemes must be employed at the power amplifier. Both high linearity requirements and next generation modulation schemes yield high power RF amplifiers with only 8% to 16% power efficiency using today's technology. One of the goals of this research is to improve high power RF amplifier efficiency to over 50% in next generation system. A multi-band frequency and multi-sector ground based Naval radio base station consumes 4000W to 5000W of power from its -48V DC power input. More than half of this power is consumed by the RF high power amplifiers. The RF power amplifiers are also the least reliable component in the base station due to the high operating temperatures created by their high heat dissipation. Another 4000 to 5000W is consumed by the AC to DC power system and air conditioning system. Furthermore, large banks of lead-acid batteries are used to back up the system. The proposed research could result in greater 50% reduction in heat produced by the base station. Consequently, focusing on the power amplifier will reduce power consumption, improve reliability, reduce system cost, reduce battery count, and reduce size and weight for the entire radio base station. The goal of this program - developing breakthrough performance improvement in high power amplifiers for the wireless communication systems - will benefit the E2 Advanced Hawkeye - and more generally the NAVAIR telecommunication sector.