GaN Technology for GPS L-band Space Power Amplification

ABSTRACT:Linearizer Technology, Inc. (LTI) and its space hardware organization Linear Space Technology, LLC (LST) propose to produce an L-band GaN high power amplifier (HPA) exceeding GPS requirements with the highest possible power added efficiency (PAE) for use in space.Minimizing HPA cost is a primary design parameter.LST has significant experience with flight HPAs and has 100 linearizers and HPAs in orbit.LTI/LST has demonstrated its ability to provide a UHF space PA with the highest PAE reported in the literature.LTI/LSTs work at UHF has shown that the key factors to achieving high efficiency aredevice selection and circuit topology.Its UHF PA required a higher linearity than specified for GPS.However, GPS still needs some linearity.Even small improvements in space can be important.LTI/LST will use its expertise in linearization to give its HPA design a PAE advantage.It has designed an L-band HPA meeting power and PAE goals using U.S. made Gallium Nitride (GaN) devices.In Phase I, LTI/LST exploited its GaN HPA experience to produce a demonstration HPA exceeding design goals.LTI/LST will use its knowledge of space hardware to insure a qualifiable design.In Phase II, LTI/LST will design and fabricate a space-qualified HPA.BENEFIT:Highly efficient high power amplifiers (HPAs) are needed for the transmission from satellites of GPS signals at L-Band.Present transmissions require relatively low linearity (AM/PM < 2.5 dB/deg.) but a high power (400 watts).The proposed HPA will take advantage of recent technical advances in solid-state device efficiency resulting from the introduction of space-qualified Gallium Nitride (GaN) HEMTs.Linearizer Technology, Inc. with its space hardware organization Linear Space Technology, LLC (LTI/LST) will use linearization to gain an advantage in power added efficiency (PAE) over non-linearized HPAs.Linearization will also allow the proposed HPA to function efficiently with new modulation formats under consideration that will require higher linearity.LTI/LST will use its relatively small size and the 300 plus years of spacecraft manufacturing experience of its staff to control costs.Its Phase I demonstration HPA has met or exceeded all design goals, and offers the following features:Flight qualified GaN power HEMTs selected for highest efficiencyPredistortion linearization for improved AM/PM performance resulting PAE advantage and ability to efficiently operate with potential future modulations.Commandable saturated power over a 5 dB rangeCommon packaging design that allows operation at GPS L1, L2 or L5 frequenciesCommand and control electronics with proven radiation hardnessSurface-mount architecture with stripline combiners providing sufficient multipactor tolerance