18 May 2006 Adaptive power amplifiers for military and commercial communications
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Architectures are discussed in which power amplifiers are able to vary their performance characteristics in response to changing output power levels, frequencies, load impedance levels and linearity constraints. Necessary elements for implementation of such systems are reviewed, including sensors to detect changes in the external environment, actuators to adapt the amplifier characteristics, and algorithms to implement the associated control functions. An example is described of a power amplifier for cell phone applications that measures the load impedance provided by the antenna and varies its output impedance match accordingly, in order to preserve output power, efficiency and linearity as the external antenna is handled. The system automatically provides output tuning for a 1W linear amplifier, and can accommodate output standing wave ratios up to 8:1. It improves output power and efficiency by x2 in representative mismatch scenarios. The insertion loss of the system is comfortably low at 0.5dB.
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Peter M. Asbeck, Peter M. Asbeck, Dongjiang Qiao, Dongjiang Qiao, } "Adaptive power amplifiers for military and commercial communications", Proc. SPIE 6232, Intelligent Integrated Microsystems, 62320T (18 May 2006); doi: 10.1117/12.669447; https://doi.org/10.1117/12.669447

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