Power amplifier

1. A power amplifier comprising:

at least a first amplifier circuit comprising an output port;

at least a second amplifier circuit comprising an output port;

at least a coupler comprising a first and a second input port and a first and a second output port, the first input port of the coupler being coupled with the output port of the first amplifier circuit and the second input port of the coupler being coupled with the output port of the second amplifier circuit; and

a switch comprising at least one input terminal and at least two output terminals, the input terminal of the switch being coupled with the first output port of the coupler, each of the output terminals of the switch being connected with a separate terminal impedance, the separate terminal impedances having different impedance values.

2. The power amplifier according to claim 1 , wherein one of the separate terminal impedances is a nominal terminal impedance having 50 Ohm and another one of the separate terminal impedances is a non-nominal terminal impedance.

3. The power amplifier according to claim 2 , wherein the impedance value of the non-nominal terminal impedance is substantially lower than the impedance value of the nominal terminal impedance.

4. The power amplifier according to claim 3 , wherein the impedance value of the non-nominal terminal impedance is less than 5 Ohm.

5. The power amplifier according to claim 2 , wherein the impedance value of the non-nominal terminal impedance is substantially higher than the impedance value of the nominal terminal impedance.

6. The power amplifier according to claim 5 , wherein the impedance value of the non-nominal terminal impedance is higher than 1 kOhm.

7. The power amplifier according to claim 1 , comprising a further coupler comprising a first and second input port and a first and second output port, the first output port of the further coupler being coupled with an input port of the first amplifier circuit, the second output port of the further coupler being coupled with an input port of the second amplifier circuit, the first input port of the further coupler being coupled with an input port of the power amplifier, and the second input port of the further coupler being coupled with a terminal impedance.

8. The power amplifier according to claim 7 , comprising a further switch comprising at least an output port and at least a first and a second input port, the output port of the further switch being coupled with the second input port of the further coupler, and each of the input terminals being connected with a separate terminal impedance, the separate terminal impedances having different impedance values.

9. The power amplifier according to claim 8 , wherein one of the separate terminal impedances is a nominal terminal impedance having 50 Ohm and another one of the separate terminal impedances is a non-nominal terminal impedance.

10. The power amplifier according to claim 1 , further comprising at least an amplifier control switch, the amplifier control switch being coupled with at least with one of the first and second amplifier circuits for selectively activating the respective amplifier circuits.

11. The power amplifier according to claim 1 , wherein the coupler is a branch-line coupler.

12. A power amplifier comprising:

at least a first amplifier circuit comprising an input port;

at least a second amplifier circuit comprising an input port;

at least a coupler comprising a first and a second input port and a first and a second output port, the first output port of the coupler being coupled with the input port of the first amplifier circuit, the second output port of the coupler being coupled with the input port of the second amplifier circuit, and the first input port of the coupler being coupled with an input port of the power amplifier; and

a switch comprising at least one output terminal and at least two input terminals, the output terminal of the switch being coupled with the second input port of the coupler, and each of the input terminals of the switch being connected with a separate terminal impedance, the separate terminal impedances having different impedance values.

13. The power amplifier according to claim 12 , wherein one of the separate terminal impedances is a nominal terminal impedance having 50 Ohm and another one of the separate terminal impedances is a non-nominal terminal impedance.

14. The power amplifier according to claim 13 , wherein the impedance value of the non-nominal terminal impedance is substantially lower than the impedance value of the nominal terminal impedance.

15. The power amplifier according to claim 14 , wherein the impedance value of the non-nominal terminal impedance is less than 5 Ohm.

16. The power amplifier according to claim 13 , wherein the impedance value of the non-nominal terminal impedance is substantially higher than the impedance value of the nominal terminal impedance.

17. The power amplifier according to claim 16 , wherein the impedance value of the non-nominal terminal impedance is higher than 1 kOhm.

18. The power amplifier according to claim 12 , comprising a further coupler comprising a first and second input port and a first and second output port, the first input port of the further coupler being coupled with an output port of the first amplifier circuit, the second input port of the further coupler being coupled with an output port of the second amplifier circuit, the second output port of the further coupler being coupled with an output port of the power amplifier.

19. The power amplifier according to claim 18 , comprising a further switch comprising at least one input terminal and at least two output terminals, the input terminal of the further switch being coupled with the first output port of the further coupler, and each of the output terminals of the further switch being connected with a separate terminal impedance, the separate terminal impedances having different impedance values.

20. The power amplifier according to claim 19 , wherein one of the separate terminal impedances is a nominal terminal impedance having 50 Ohm and another one of the separate terminal impedances is a non-nominal terminal impedance.

21. The power amplifier according to claim 12 , further comprising at least one amplifier control switch coupled with at least one of the first and second amplifier circuits for selectively activating the respective amplifier circuits.

22. The power amplifier according to claim 21 , wherein the coupler is a branch-line coupler.

23. A power amplifier comprising:

a first amplifying means for amplifying a signal;

a second amplifying means for amplifying a signal;

a coupling means comprising a first and a second output port, and for combining the signals amplified by the first and second amplifying means at the second output port of the coupling means; and

a switching means coupled to the first output port of the coupling means, and for selectively coupling the first output port of the coupling means with separate terminal impedances.

24. The power amplifier according to claim 23 , wherein the first and second amplifier means are selectively operable.

25. A method for operating a power amplifier comprising the steps of:

splitting an input signal to provide at least two split signals;

amplifying each of the split signals by at least two amplifier circuits;

combining the amplified split signals by a coupler at an output port of the coupler, wherein another output port of the coupler is coupled with a nominal terminal impedance; and

reducing the output power of the power amplifier by:

deactivating one of the two amplifier circuits;

disconnecting the nominal terminal impedance from the another output port of the coupler; and

connecting a non-nominal terminal impedance having an impedance value being different from the impedance value of the nominal terminal impedance with the another output port of the coupler.