Amplifying device
The present invention concerns a composite amplifier and a method for controlling the amplitude of a composite amplifier in a node of a wireless communication system. The composite amplifier comprises a first amplifier and a second amplifier that are arranged to be connected via an output combiner network to a load. The method comprises decomposing an input signal into a first signal component and a second signal component. Further, the method comprises differentiating the amplitude on the first signal component from the amplitude on the second signal component. the differentiation is made such that the aggregated efficiency of the composite amplifier is increased. The present invention also concerns a radio transmission device comprising a composite amplifier.
1. Method for controlling an amplitude of a composite amplifier in a node of a wireless communication system, said composite amplifier comprising a first amplifier and a second amplifier that are arranged to be connected via an output combiner network to a load, the method comprising:
decomposing an input signal into a first signal component and a second signal component,
phase shifting at least one of the first signal component and the second signal component to generate first and second phase differentiated signal components;
differentiating an amplitude of the first and second phase differentiated signal components to generate first and second phase-amplitude differentiated signal components;
generating a pre-distortion signal responsive to a difference between amplitudes of the first and second phrase-amplitude differentiated signal components;
combining the pre-distortion signal with each of the first and second phase-amplitude differentiated signal components to generate first and second compensated signal components; and
supplying the first compensated signal component to the first amplifier and the second compensated signal component to the second amplifier.
2. Method according to claim 1 , further comprising:
combining the first compensated signal component and the second compensated signal component to form an output signal.
3. Composite amplifier for use in a node of a wireless communication system, said composite amplifier comprising:
a control unit configured to decompose an input signal into a first signal component and a second signal component, to phase shift at least one of the first signal component and the second signal component to generate first and second phase differentiated signal components, to differentiate an amplitude of the first and second phase differentiated signal components to generate first and second phase-amplitude differentiated signal components, to generate a pre-distortion signal responsive to a difference between amplitudes of the first and second phase-amplitude differentiated signal components, and to combine the pre-distortion signal with each of the first and second phase-amplitude differentiated signal components to generate first and second compensated signal components;
a first amplifier that is connected to amplify the first compensated signal component;
a second amplifier that is connected to amplify the second compensated signal component; and
an output combiner network configured to combine the amplified first and second compensated signal components for supply to a load.
4. Radio transmission device comprising:
at least one composite amplifier that comprises:
a control unit configured to decompose an input signal into a first signal component and a second signal component, to phase shift at least one of the first signal component and the second signal component to generate first and second phase differentiated signal components, to differentiate an amplitude of the first and second phase differentiated signal components to generate first and second phase-amplitude differentiated signal components, to generate pre-distortion signal responsive to a difference between amplitudes of the first and second phase-amplitude differentiated signal components, and to combine the pre-distortion signal with each of the first and second phase-amplitude differentiated signal components to generate first and second compensated signal components;
a first amplifier that is connected to amplify the first compensated signal component;
a second amplifier that is connected to amplify the second compensated signal component; and
an output combiner network configured to combine the amplified first and second compensated signal components for supply to a load.
5. Radio transmission device according to claim 4 ,where the radio transmission device is a wireless access point, and the load comprises an antenna of the wireless access point.
6. A radio transmission device according to claim 4 ,where the radio transmission device is a wireless terminal, and the load comprises an antenna of the wireless terminal.