Doherty power amplifier for radio-frequency applications

A wireless device comprising:

• a transmitter circuit configured to generate a signal;
• a power amplifier configured to amplify the signal, and including a carrier amplifier having first and second differential amplification cells with outputs coupled by a primary loop of a carrier transformer, and a peaking amplifier having first and second differential amplification cells with outputs coupled by a primary loop of a peaking transformer, the power amplifier further including a combiner having a quarter-wave circuit implemented between a first end of a secondary loop of the carrier transformer and a first end of a secondary loop of the peaking transformer, the quarter-wave circuit configured such that the carrier and peaking amplifiers are presented with a desired impedance when both of the carrier and peaking amplifiers are turned on, and the carrier amplifier is presented with an impedance that is approximately twice the desired impedance when the carrier amplifier is turned on and the peaking amplifier is turned off, the power amplifier further including an output node implemented at a second end of the secondary loop of the carrier transformer;
• and
• an antenna in communication with the output node of the power amplifier and configured to support transmission of the amplified signal.