A Novel Power Splitting for 1.2–5.7-GHz Dual-Input Power Amplifier Using Sigmoid Function and Nonlinear Support Vector Machin

This study introduces a novel splitting function for the multimode dual-input power amplifier (PA) with the proposed optimization supported by a nonlinear support vector machine (SVM). The fabricated PA utilizes independent dual input and a broadband load-modulated output combiner, enabling the PA to operate in both Doherty and outphasing modes. The operation mode is controlled by the power ratio and the phase difference between the two inputs, which should be appropriately assigned to correspond with the operation mode. Nonlinear SVM can identify the operation mode and reduce the number of iterations to optimize the performance of the multimode dual-input PA. An input signal is converted to two input signals based on the sigmoid function, which simplifies the signal processing. The multimode dual-input PA is fabricated with 0.15- $\mu $ m GaN HEMT and achieves 28.1–31.7 dBm of average output power, 36%–56% of power added efficiency (PAE), and less than −47 dBc of ACPR over a wide bandwidth from 1.2 to 5.7 GHz.