Integrated Filtering Class-F Power Amplifier Based on Microstrip Multimode Resonator
Li‐Heng Zhou, Xin Yu Zhou, Wing Shing Chan, Jing Zhou Pang, Derek Ho
Abstract
Filtering power amplifiers (PAs) combine two functions into one circuit and 2-order cascaded structure with two transmission poles (TPs) is the most common form. Multiple TPs can extend bandwidth and minimize in-band ripple. However, more resonators are required for traditional topologies, resulting in large size with high loss. A microstrip filtering Class-F is proposed based on the couple-line multimode impedance transformer (IT) in this paper. Four TPs are created by using only a single resonator. Lengths of the drain bias stub and coupled feed line are carefully chosen to meet the requirement for Class-F operation. The fabricated multimode filtering Class-F PAs is measured at 3.6 GHz for 5G applications. Maximum gain at saturation is 12 dB with output power P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">out</inf> >38.5 dBm. Maximum power added efficiency (PAE) is 63%, while the effective bandwidth is 400 MHz under the condition of PAEs > 50%.