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Reduction of undesired harmonic components

  • US 4,811,422 A
  • Filed: 12/22/1986
  • Issued: 03/07/1989
  • Est. Priority Date: 12/22/1986
  • Status: Expired due to Term
First Claim
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1. The method of reducing the power of undesired radio frequency (rf) harmonics produced by a transmitter incorporating a highest power power amplifier comprising the following steps:

  • (a) amplifying a desired rf signal, to a selected power level in the highest power power amplifier whereby said amplified signal may contain undesired rf harmonically related components.(b) coupling the amplifier to an output terminal so as to provide a first, main path for the desired signal and all associated harmonics, said path attenuating the associated harmonics by at least 6 db,(c) providing an alternate path from the amplifier to the output for at least the harmonics that are above the harmonics that are above an acceptable level in the first path,(d) controlling the phase of the harmonics referred to in step (c) so as to cause them to reach the output terminal substantially 180 degrees out of phase with each corresponding harmonic from the first path, and(e) amplifying the harmonics of step (d) so as to cause them to reach the output terminal substantially equal in amplitude to the corresponding harmonics from the first path, thereby substantially attenuating said harmonics when they combine at the output terminal.

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