The analysis of, and derivation of design equations for, a class-B balanced single-endeddual-fed distributed amplifier is presented. This approach allows efficient combining of FET outputpower without multi-way power combiners, has a good port match, and is easy to design as thegate and drain transmission lines are uniform. The design method ensures that all FETs areoptimally used and the efficiency is comparable to that of a conventional single-transistor class-Bpower amplifier using the same FET type. The design method was applied to a class-B four-FETbalanced single-ended dual-fed distributed amplifier designed to operate at 1.8GHz. Large-signalmeasurements revealed 8% downward shift of the centre frequency. The measured output powerand drain efficiency was consistent with the simulations. The efficiency of the amplifier wascomparable to a conventional single-transistor class-B power amplifier using the same type of FET.
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