MINIATURIZED DUAL-BAND MATCHING TECHNIQUE BASED ON COUPLED-LINE TRANSFORMER FOR DUAL-BAND POWER AMPLIFIERS DESIGN

This study presents a novel miniaturized dual-band coupled-line impedance transformer. This dual-band matching technique uses the characteristics of coupled-line and dual-band stubs to realize matching arbitrary complex impedance to arbitrary complex impedance at two arbitrary uncorrelated frequencies. Especially, it satisfles the demand of dual-band matching at two relatively closed operating frequencies (n = f2=f1 • 1:2), and occupy a very small circuit area with inherent DC-Block function. The proposed synthesis approach is validated by the design and fabrication of a 30W gallium nitride (GaN)-based class-AB power amplifler (PA) for GSM and WCDMA at 1800MHz and 2140MHz. The PA's output matching network based on the proposed structure can accurately match 50› to the ideal load impedances of the transistor at two designed frequency simultaneously and has 20% and 15% bandwidth for which the re∞ection coe-cient magnitudes are less than 0.1, respectively.