High-Power 20-100-MHz Linear and Efficient Power-Amplifier Design

This paper presents modeling and analysis of the realization of high-power broadband RF power amplifiers (PAs) and power combiners. In the scope of the study, a model is proposed for a transmission line with a ferrite core, which is the basic building block for the transmission line transformers (TLTs) used in broadband high-power amplifiers and power combiner/divider networks as a building block. Simulated performances of the designed networks using the proposed model possess high conformity with the empirical performance of the corresponding realized networks. Therefore, broadband TLT networks with low insertion loss, high power-handling capability, and low return loss are realized. RF power combiner/divider networks with wide frequency bandwidth and high isolation are also implemented. By using class-B biased pushpull network topology, a linear and wideband RF PA is realized with high drain efficiency at high output power levels. In order to broaden the operating frequency range of the indicated amplifier, a novel technique for TLT utilization that matches the output impedance of the RF power transistor in wideband is proposed and realized. Measurement results satisfy the design specifications.