A 1.7–2.5-GHz GaAs MMIC Doherty Power Amplifier With an Ultrawideband Output Network for Mobile Terminals

This letter presents an ultrawideband output network and its corresponding design methodology for integrated Doherty power amplifiers (DPAs). By eliminating the peaking output matching network and utilizing the nonfixed impedance trajectory of the post-matching network, the proposed output network significantly extends the operational bandwidth of DPA while reducing the chip area. For experimental validation, a two-stage DPA prototype is implemented using a 250-nm GaAs process, resulting in a chip area of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.3\times 1.8$ </tex-math></inline-formula> mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. The measured results demonstrate a saturation output power ranging from 34.0 to 34.5 dBm and a power-added efficiency (PAE) of 44.4%–56.9% across 1.7–2.5 GHz. At 6-dB output power back-off point, PAE maintains 33.5%–41.2%, with associated gain values of 23.1–27.3 dB. When driven by a 100-MHz 64-QAM signal with 6.5-dB peak-to-average power ratio (PAPR), the implemented design achieves an adjacent channel leakage ratio (ACLR) below −45 dBc with digital predistortion.