A fully analog two-way sequential GaN power amplifier with 40% fractional bandwidth

In this paper, we report a two-way sequential power amplifier (SPA) using GaN HEMTs. The proposed fully analog SPA delivers P_sat of approximately 40dBm over 2-3 GHz covering 40% fractional bandwidth. The design consists of a 3dB input coupler, a main amplifier, a peak amplifier, and a 10dB output coupler for power combining.

After proper designing and optimizing these critical wideband couplers in terms of both phase and amplitude alignment, the measured final SPA shows 45% to 61% drain efficiency (DE) at 35dBm (5dB backoff) output from 2.1 to 2.9 GHz under CW stimulus. A complete set of SPA with analog RF input and output network is demonstrated.

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