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AM-FM transmitter power amplifier using class-BC

  • US 5,570,062 A
  • Filed: 10/12/1994
  • Issued: 10/29/1996
  • Est. Priority Date: 10/12/1994
  • Status: Expired due to Term
First Claim
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1. A power amplifier circuit for efficiently generating an output signal into a load at more than one alternative power level, comprising:

  • at least two amplifying means, each having optimum efficiency at different power output levels;

    drive signal means, coupled to the at least two amplifying means, for selectively activating any one of the at least two amplifying means and for deactivating all amplifying means that have not been selected for activation, whereinthe activated amplifying means generates the output signal to be supplied to the load; and

    selection is based on amplitude of a modulating signal having a frequency that is slower than that of a carrier signal being supplied as an input to the power amplifier circuit; and

    coupling means, coupled to each of the at least two amplifiers and to the load, for coupling the at least two amplifying means to the load in a manner such that signal power flowing from the activated amplifying means to the load is not impeded by the deactivated amplifying means.

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