Patent ID: 8917141

Claim:
An amplifier circuit for providing a radio frequency output signal having a variable signal envelope, comprising: a main amplifier device having an input and an output for outputting a first radio frequency output signal; an auxiliary amplifier device having an input and an output for outputting a second radio frequency output signal; a combiner network for combining at least a component of said first radio frequency output signal from said main amplifier device and at least a component of said second radio frequency output signal from said auxiliary amplifier device to provide a combined output signal of variable signal envelope to a load; and a signal processing circuit comprising: an input for receiving an input signal; a first output coupled to the input of the main amplifier device for providing a first radio frequency signal to be amplified by said main amplifier device; and a second output coupled to the input of the auxiliary amplifier device for providing a second radio frequency signal to be amplified by said auxiliary amplifier device; wherein said signal processing circuit comprises a non-linear processing section coupled to the input of the signal processing circuit and adapted to provide at least said second radio frequency signal with a signal envelope that has a non-linear dependency from an amplitude characteristic of the input signal; wherein: the non-linear processing section is adapted such that a degree of non-linearity of the non-linear dependency varies dependent on an amount of change per time unit of the amplitude characteristic of the input signal.