volume | PIER Journals

Abstract

This study designs and experimentally validates a digitally controlled 2.45 GHz solid-state microwave power source for industrial continuous-wave operation. The source employs a cascaded laterally diffused metal oxide semiconductor (LDMOS) architecture integrating a phase-locked loop frequency synthesizer, a multi-stage driver chain, and a closed-loop digital power-control network with 0.5-dB resolution. The final-stage power amplifier (PA) is biased in deep class-AB, and a lumped-element matching network is synthesized - guided by load-pull and harmonic-impedance analysis - to realize a near-short termination at the second harmonic and reduce voltage-current overlap energy. Nonlinear device modelling and system-level analysis are used to predict efficiency and stability. Measurements show a saturated output power of 54.09 dBm, gain of 18.14 dB, and peak power-added efficiency of 61.89% under a 28-V supply. The source achieves accurate continuous-wave (CW) power regulation from 35 to 53 dBm with good thermal stability. These results indicate that combining deep class-AB biasing with second-harmonic near-short termination enables high-efficiency operation in L/S-band industrial microwave sources, and the cascaded digitally controlled architecture provides robust power management for microwave heating and plasma excitation systems.

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Mr. Zhiqi Li

Professor Dan Zhang

Dr. Yan Sun