CPC H03F 1/42 (2013.01) [H03F 3/245 (2013.01); H03F 2200/09 (2013.01); H03F 2200/36 (2013.01); H03F 2200/451 (2013.01)] | 20 Claims |
1. An amplifier, comprising:
an amplifier core circuit configured to amplify a radio frequency signal and having a first output and a second output;
a transformer coupled to the amplifier core circuit, the transformer having a primary winding and a secondary winding, the primary winding being coupled to the first output and the second output of the amplifier core circuit, the secondary winding being coupled to an output node of the amplifier; and
a variable resistance circuit coupled in parallel with the primary winding,
wherein the output node is coupled to an input of another amplifier, and
wherein the amplifier comprises a driver amplifier in a transmit path of a user terminal, the other amplifier comprises a power amplifier in the transmit path, and the transformer comprises a balun configured to convert differential signaling in the driver amplifier into a single-ended output, the single-ended output being coupled to a single-ended input of the power amplifier.
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