A study on high-efficiency short-wave AM transmitter

In a short-wave (3 to 30 MHz) high-power transmitter, the modulation section is fabricated with semiconductors, but the total semiconductor realization including the final-stage PA is difficult and has not been accomplished to date. The authors' objective is to achieve total use of semiconductors for realization of a 100-kW-class short-wave high-power transmitter. An optimal power device (MOSFET) to obtain high efficiency is selected. In addition, a circuit for realization of high efficiency and a synthesis method for excellent linearity are proposed. In the short-wave band, there is a problem of increased loss due to parasitic diodes for the digital-processing AM modulation device used in the middle-frequency range. It is shown that the method cannot be applied directly. Further, an optimum modulation format and a circuit configuration for realization of a short-wave high-efficiency AM transmitter are proposed. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(3): 33–41, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20283