Wideband doherty amplifier circuit having a constant impedance combiner

摘要

A three way wideband Doherty amplifier circuit includes a first peaking amplifier operable to turn on at a first power level, a second peaking amplifier operable to turn on at a second power level below the first power level and a main power amplifier operable to turn on at all power levels. The main power amplifier has a high impedance load modulated state when the first and second peaking amplifiers are turned off. The three way wideband Doherty amplifier circuit further includes a constant impedance combiner connected to an output of each amplifier. The constant impedance combiner has a characteristic impedance which matches the impedance of the main amplifier in the high impedance load modulated state with or without an output matching device connecting the main amplifier output to the constant impedance combiner, as viewed from the output of the main amplifier.