Experimental Studies of Envelope Elimination and Restoration HF Power Amplifier Characteristics with Narrow-band Matched Load
Oleg V. Varlamov, A. V. Grebennikov
Abstract
This article demonstrates experimental studies characteristics of the envelope elimination and restoration (EER) 300 W HF power amplifier (PA) operating with narrow-band matched load. The narrow-band high-Q antenna circuit model with an inductance Q-factor equal to 360 was calculated and manufactured. Experimental studies of EER PA have shown that the narrow-band load mismatch, in comparison with the wideband one, leads to a more significant distortion of the amplified signal. To ensure regulatory requirements for out-of-band emissions, it is permissible for the EER PA to operate at a narrow-band load with VSWR <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> = 1.5 for "soft" mask and not more than VSWR <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> = 1.13 for "strict" mask. To ensure the modulation error ratio (MER) of 30dB, accepted as some standards, the narrow-band load must provide a VSWR <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> <1.57.