A concise high-efficiency broadband parallel-circuit Class-E power amplifier

An analysis of a single-ended high-efficiency broadband parallel-circuit (PC) Class-E power amplifier (PA) with a single reactance compensation technique (RCT) and low-pass (LP) Chebyshev impedance transformer is first presented under low supply voltage. Analysis of the gate and drain voltage allows to determine the required optimum voltage values for the expected PA design objectives. Derivation and design procedure of the broadband matching network (MN) is provided, which can effectively filter out higher order harmonics and reduce circuit complexity. In addition, the load adaptability for this PA is studied, achieving higher than 67.87% drain efficiency (DE) in the case of load mismatch. A PC Class-E PA based on NMOS transistor is designed and implemented to validate the analysis over a frequency band of 7–9.4 MHz. Experimental results show that the PA delivers 36.48–38.83 dBm output power with a DE of 84.91% to 86.91%, as well as achieves 83.98% to 86.28% power-added efficiency (PAE), 19.48–21.83 dB gain with a low supply voltage of 12 V. It is also demonstrated that the experimental results exhibit good agreement with the simulation results, which prototype the radio frequency identification transmitter with broadband high-efficiency and system compactness. To the author's knowledge, this study represents the first approach to design broadband PC Class-E PA under low supply voltage for Internet of Things (IoT) applications at HF frequency band, such as electronic article surveillance (EAS) system.