Amplifier

Abstract

There is provided an amplifier for combining outputs of a plurality of amplifying circuits to generate an amplifier output. The amplifier includes a first amplifying circuit for operating a first amplifying device in class-AB, wherein the first amplifying circuit is one among the plurality of the amplifying circuits; a second amplifying circuit for operating a second amplifying device in class-B or class-C, wherein the second amplifying circuit is one among the plurality of the amplifying circuits; and a summing node at which an output of the first amplifying circuit is combined with an output of the second amplifying circuit via a first impedance transformer containing a transmission line of an electrical length other than λ/4. The second amplifying device is connected to the summing node via an output matching circuit and a second impedance transformer containing a transmission line.

1 - 3 . (canceled) 
   
   
       4 . An amplifier comprising:
 a divider for dividing an input signal of the amplifying circuit into at least two divided signals;   a first preamplifier for amplifying one of the divided signals and a second preamplifier for amplifying another of the divided signals;   a carrier amplifying circuit for amplifying an output of the first preamplifier;   a peak amplifying circuit for amplifying an output of the second preamplifier if the output of the second preamplifier is higher than a threshold level; and   a Doherty combiner for combining an output of the carrier amplifying circuit with an output of the peak amplifying circuit.   
   
   
       5 - 9 . (canceled) 
   
   
       10 . The amplifier of  claim 4 , wherein the first and the second preamplifier includes at least one cascaded amplifier, respectively.