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

摘要

The 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.