Patent ID: 8649744

Claim:
An apparatus, comprising: a digital pre-distortion circuit configured to pre-distort a digital input signal to generate a first pre-distorted digital signal and a second pre-distorted digital signal different from the first pre-distorted signal; a first amplifier branch configured to generate a first amplified signal based on the first pre-distorted digital signal; a second amplifier branch configured to generate a second amplified signal based on the second pre-distorted digital signal; and a radio-frequency (RF) circuit configured to combine the first and second amplified signals to generate a combined signal, wherein: the RF circuit is further configured to generate first and second feedback signals based on at least two of the first amplified signal, the second amplified signal, and the combined signal; the digital pre-distortion circuit is configured to generate the first pre-distorted digital signal and the second pre-distorted digital signal based on said first and second feedback signals to counteract nonlinearity in the first and second amplifier branches: and the RF circuit comprises a first transcoupler, said first transcoupler comprising: a first branch connected between an output port of the first amplifier branch and an output port of the second amplifier branch; and a second branch electromagnetically coupled to the first branch and having first and second terminals, wherein the first terminal is configured to carry the first feedback signal.