Design of a multi‐octave power amplifier using broadband load‐pull X‐parameters

Abstract

AbstractThe design of a multi‐octave power amplifier (PA) based on a broadband load‐pull X‐parameter model is described for the first time in this work. A 10‐W GaN package transistor is employed for model X‐parameter model extraction. Once the model is extracted, it is compared with the equivalent circuit model provided from the device manufacturer, and it is found that the X‐parameter model accuracy is comparable to that of the original circuit model. In particular, the X‐parameter model can accurately determine the areas of the load Smith chart leading to optimal output power and drain efficiency, essential considerations for extracting maximum device performance. A Chebyshev low‐pass architecture is utilized for both the input and the output matching network designs. Finally, a multi‐octave bandwidth PA, from 0.6 to 2.3 GHz, is designed. Simulation results of the broadband X‐parameter model and the measured results of the realized PA are compared, with a high fidelity match evident, thus demonstrating the efficacy of the design procedure of multi‐octave PA with broadband X‐parameters. The output power of the realized PA across the operating frequency band remains between 39.51 and 42.41 dBm, while the drain efficiency remains above 60%, reaching as high as 73% around 2 GHz. The gain of the PA is greater than 11 dB over the complete frequency band.