Bandpass Filtering Power Amplifier With Extended Band and High Efficiency

This letter presents a wideband power amplifier (PA) with high efficiency integrated filtering characteristic. A novel bandpass filtering impedance transformer was proposed, which consists of a terminated coupled line structure (TCLS) and impedance tuning network (ITN), to realize the input matching network (IMN) and output impedance matching network (OMN). To enhance the efficiency of PA, the second harmonic has also been controlled perfectly. This design method can not only provide high-selectivity bandpass responses and high efficiency but also broaden the operation band. For demonstration, a wideband filtering PA operating at 2.2 GHz with a bandwidth of 400 MHz by employing a 10-W GaN HEMTs is fabricated. Measured results show the maximum drain efficiency (DE) is 68.3%-78.4% in the design band. Meanwhile, a good filtering performance was obtained. The rejection level was larger than 52.8 and 31 dB for the lower and higher suppression bands, respectively. In addition, simulation results show that the IMD2 and IMD3 were also improved simultaneously. In particular, the IMD2 value was improved about 30-40 dB.