Patent ID: 8442460

Claim:
A method for compensating signal distortions in multiple transmitting branches entering a composite amplifier comprising the steps of: providing one or more input signals to the composite amplifier; observing an output signal from the composite amplifier for each provided input signal; deriving an error in the output signal by comparing the output signal with an ideal output signal, said error being caused by said signal distortions; deriving the individual contribution from each transmitting branch to the error by utilising a composite amplifier model, said composite amplifier model comprising information about the contribution from each constituent amplifier to the output signal for each provided input signal; and compensating the signal distortions in the transmitting branches accordingly, wherein the step of providing one or more input signals to the composite amplifier comprises providing a first input signal and a second input signal to the composite amplifier; the method further comprises: using the ideal output signal to produce a first signal and a second signal; producing a first compensation parameter and a second compensation parameter; providing the first signal to a first compensating circuit configured to distort the first signal based on the first compensation parameter, thereby producing a first distorted signal; providing the second signal to a second compensating circuit configured to distort the second signal based on the second compensation parameter, thereby producing a second distorted signal; providing the first distorted signal to a first transmission circuit comprising a first modulator, wherein the first transmission circuit is configured to use the first distorted signal and the first modulator to generate the first input signal, wherein the first input signal is a modulated signal; providing the second distorted signal to a second transmission circuit comprising a second modulator, wherein the second transmission circuit is configured to use the second distorted signal and the second modulator to generate the second input signal, wherein the second input signal is a modulated signal, and the step of producing the first and second compensation parameters comprises: (i) comparing the output signal with the ideal output signal to produce an error signal and (ii) determining the first and second compensation parameters using the error signal and the composite amplifier model.