부산대학교 도서관

We present a diplexed power amplifier (PA) architecture for achieving more than octave bandwidth with high efficiency. Two relatively narrowband single-stage PAs are connected with a contiguous diplexer-combiner network. The average efficiency across the larger than octave band is maintained with a flat gain response from 1.8 to 4 GHz. To maintain efficiency, the two transistors are biased in class B. One of the paths is turned on in each subband, and in the transition region, the two PAs power combine. In both element amplifiers, a 7-W Qorvo GaN packaged device is used to achieve approximately 35% fractional bandwidth, from 1.8 to 2.7 and 3 to 4 GHz, respectively. Averaged over the full band, the amplifier achieves an average measured power-added efficiency of 43.7%, the output power of 38.0 dBm, and the gain of 8.8 dB. Linearization using digital predistortion is demonstrated, with the benefit of reduced complexity due to the frequency isolation of the two PA branches.