Optimization Design of Ultra-Wideband PA With Fragment-Type Structure Using Load Impedance Overlap and Geometrical Constraint

This article presents an optimization design method for high-efficiency, ultra-wideband power amplifier (PA). To address the challenge of frequency overlap in multioctave PA designs, a multioctave load impedance analysis method is proposed, which can effectively identify the optimal load impedance regions for the frequency bands with fundamental and harmonic frequency overlap. For maximized utilization of these load impedance regions, a novel impedance constraint strategy is proposed by employing an inscribed polygon to geometrically constrain the target load impedances. Then, a ray casting algorithm is used to determine whether the impedance obtained by the output matching network (OMN) is within the polygonal constraint region. Moreover, to increase design flexibility, a fragment-type matching circuit is employed in the OMN design using an integrated optimization simulation platform to realize fundamental and harmonic impedance matching precisely across the operational bandwidth, thereby overcoming bandwidth limitations of the conventional wideband PAs. Experimental results show that an ultra-wideband PA is realized from 10–4000 MHz (199% fractional bandwidth) with 58.0%–70.6% drain efficiency (DE) and 39.2–42.0 dBm saturated power.