| CPC H03F 1/0211 (2013.01) [H03F 1/0261 (2013.01); H03F 1/0288 (2013.01); H03F 1/223 (2013.01); H03F 1/3205 (2013.01); H03F 1/3217 (2013.01); H03F 1/56 (2013.01); H03F 3/193 (2013.01); H03F 3/195 (2013.01); H03F 3/21 (2013.01); H03F 3/211 (2013.01); H03F 3/26 (2013.01); H03F 3/265 (2013.01); H03F 3/3028 (2013.01); H03F 2200/222 (2013.01); H03F 2200/387 (2013.01); H03F 2200/451 (2013.01); H03F 2200/534 (2013.01); H03F 2200/541 (2013.01); H03F 2200/555 (2013.01)] | 11 Claims |

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1. An amplifier comprising:
a main branch amplifier having a first input terminal and a first output terminal, the main branch amplifier biased to operate in class AB; and
an auxiliary branch amplifier having a second input terminal and a second output terminal, the auxiliary amplifier biased to operate in class C, wherein one branch is a constant current-biased branch, and another branch is a voltage biased branch, with the branches connected in cascode configuration to form a load modulated amplifier with a load connected to be driven from the auxiliary amplifier output terminal under all signal conditions so that the load connected to the auxiliary amplifier output terminal appears at the main branch amplifier output when an input signal power level is below a predetermined power level.
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