Optimization Design of Broadband Doherty PA Using Fragment-Type Matching Network Based on Dual-State Impedance Objective Function
Wa Kong, Yujie Zhong, Jing Xia, Xin Yu Zhou, Hongyan Fu, Weiqing Dong, Ziming Zhao, Xiao‐Wei Zhu
Abstract
In this brief, an optimization design of broadband Doherty power amplifier (DPA) is presented for the extension of bandwidth. A dual-state impedance objective function is utilized in the optimization of the carrier and peaking output matching networks (OMNs) to satisfy the load impedance constraints at back-off output power and saturation, respectively. Unlike conventional method, a novel impedance constraint strategy is proposed by employing an impedance constraint circle in Smith chart, which can more fully utilize the impedance region obtained from load-pull simulations. Moreover, to increase design flexibility, a fragment-type matching circuit is employed in the OMN optimization design together with the dual-state impedance objective function. Experimental results demonstrate a 1.2 to 2.6 GHz (74% fractional bandwidth) broadband DPA with a drain efficiency of 49.7%–53.5% measured at 6 dB back-off and a saturated output power of higher than 43 dBm.