Design of an efficiency-enhanced filtering power amplifier with a dual-band response and wide stopband

This article introduces an efficiency-enhanced filtering power amplifier (FPA) design that exhibits a dual-band response and excellent stopband rejection. This design effectively minimizes the need for numerous microwave components in the dual-band radio frequency front-end, leading to a smaller circuit footprint and reduced signal loss. The recommended approach entails the utilization of an output matching network (OMN), comprising a harmonic control network (HCN) and a dual-band band-pass filter (BPF) to provide dual-band impedance matchings and filtering responses simultaneously. Specifically, the HCN draws inspiration from the concept of complementary split ring resonators (CSRRs) to efficiently manage undesirable harmonic content. Additionally, the incorporation of the dual-band BPF serves the dual purpose of facilitating dual-band operation while maintaining the desired filtering characteristics. To prove the concept, a dual-band FPA was developed, utilizing a commercially available 10 W GaN HEMT. This FPA was designed to operate efficiently within two distinct frequency ranges. Our achieved findings reveal that within the lower frequency band, spanning from 1.5 to 2.1 GHz, the FPA achieves its maximum Drain Efficiency (DE) at 69.4 %. Concurrently, it demonstrates an output power reaches a notable value of 39.7 dBm at a specific frequency of 1.55 GHz. When transitioning to the upper frequency band, covering the range of 3.0 to 4.0 GHz, the FPA consistently maintains its peak DE at 80.3 %, accompanied by an output power of 42 dBm, this time at 3.6 GHz.