BROADBAND HIGH EFFICIENCY RF POWER AMPLIFIER DESIGN BASED ON MODIFIED CLASS-J APPROACH WITH APPLICATIONS USING GAN HEMT TECHNOLOGY

2021-9-29
Koç, Murat
RF power amplifiers have been the essential elements of any transmit/receive block. Especially in the transmit chain, some applications require high RF power, such as radar, jammer, telecommunication signals targeting a wide range of coverage. High power requirements in RF broadcast mean high supply power to feed RF PA. The efficiency parameter of a high-power transmission system becomes an issue due to heating problems and performance degradation depending on rising temperatures. The heating problem is commonly solved using active cooling plants. Cooling plants add extra cost demanding discrete power supplies and considerable amount of design labor. With these problems at hand, industrial and academic environments have turned to look for more efficient amplifier topologies. In this thesis, modified class-J schemes proposed to enhance operating bandwidth are studied. A modification called "normalized resistive-reactive class-J" (NRRCJ) approach is proposed. Detailed parametric analysis is presented. The effects of parameters in governing equations are discussed. A related engineering design procedure is demonstrated with an ultra-broadband GaN PA. Prototype PA operating at 400-3200 MHz capable of at least 10 W saturated output power is fabricated. Measured efficiency values of %53 - %69.8 are obtained at saturated output power. The average efficiency is calculated as %62.45. The measurement results, theoretical aspects, and expectations are compared. It is shown that the resistive termination of harmonics in a systematic way makes it possible to achieve a broadband and relatively high efficiency performance, simultaneously. The final prototype achieves remarkable compatibility with a practical RF system, compared with similar examples in the literature, in terms of size, gain, efficiency, output power and operating frequency band.

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Citation Formats
M. Koç, “BROADBAND HIGH EFFICIENCY RF POWER AMPLIFIER DESIGN BASED ON MODIFIED CLASS-J APPROACH WITH APPLICATIONS USING GAN HEMT TECHNOLOGY,” M.S. - Master of Science, Middle East Technical University, 2021.