Design of a dual‐band power amplifier over an octave bandwidth employing dual‐band resonators

In this article, a compact dual‐band resonator is proposed for designing dual‐band power amplifiers (DBPAs). The proposed resonator has the characteristics of the band‐pass filters, suppressing the out‐of band signals. It is illustrated the proposed resonator has a simple circuit topology without sacrificing the performances of the DBPA. To verify the methodology, a high efficiency DBPA prototype operating at 1.72 and 3.48 GHz is fabricated and measured. The DBPA obtains a bandwidth of 100 and 50 MHz at the low and high frequency bands, respectively. The measurement results show that the DBPA delivers a saturation power of 43.1 and 40.8 dBm at 1.72 and 3.48 GHz, respectively. The measured drain efficiencies of the DBPA are 75.4% and 68.6% at 1.72 and 3.48 GHz, respectively. Meanwhile, when the DBPA is stimulated by a 20 MHz LTE signal with a peak to average power ratio (PAPR) of 7 dB, the measured adjacent channel leakage ratios are lower than −50 dBc at both 1.72 and 3.48 GHz after digital predistortion.