Circuit and a method for generating a radio frequency signal

1. A circuit for generating a radio frequency signal, comprising:

an amplifier configured to generate the radio frequency signal based on a baseband signal,

a power supply configured to generate a variable supply voltage based on a control signal indicating a desired supply voltage, and to supply the variable supply voltage to the amplifier, and

an envelope tracking circuit configured to generate the control signal based on a compensation factor corresponding to a bandwidth of the baseband signal to compensate for a bandwidth dependent gain of the power supply, and to supply the control signal to the power supply.

2. The circuit of claim 1 , wherein the envelope tracking circuit is configured to:

generate a first control signal for a first bandwidth of the baseband signal, and supply the first control signal to the power supply; and

generate a second control signal for a higher second bandwidth of the baseband signal, and supply the second control signal to the power supply, the second control signal indicating a higher desired supply voltage than the first control signal.

3. The circuit of claim 1 , wherein the envelope tracking circuit comprises a signal analysis unit configured to calculate the bandwidth of the baseband signal.

4. The circuit of claim 3 , wherein the radio frequency signal is a radio frequency signal for Long Term Evolution communications comprising a number of allocated resource blocks, and wherein the signal analysis unit is configured to calculate the bandwidth of the baseband signal based on the number of allocated resource blocks.

5. The circuit of claim 3 , wherein the envelope tracking circuit further comprises:

a gain unit configured to generate an amplified signal by modifying an amplitude of a signal related to the baseband signal by a gain factor; and

a digital-to-analog conversion unit configured to generate the control signal for the power supply based on the amplified signal,

wherein the gain unit is configured to adjust the gain factor based on the signal bandwidth of the baseband signal.

6. The circuit of claim 5 , wherein the signal related to the baseband signal comprises information on a magnitude of the baseband signal.

7. The circuit of claim 1 , wherein the envelope tracking circuit is further configured to generate the control signal based on a frequency of the radio frequency signal.

8. The circuit of claim 7 , wherein the radio frequency signal is a radio frequency signal for Long Term Evolution communications comprising a plurality of allocated resource blocks at different frequencies of the radio frequency signal, and wherein the envelope tracking circuit is configured to generate the control signal based on a frequency related to the different frequencies of the plurality of allocated resource blocks.

9. The circuit of claim 8 , wherein the frequency related to the different frequencies of the plurality of allocated resource blocks is a center frequency of the different frequencies of the plurality of allocated resource blocks.

10. The circuit of claim 1 , wherein the envelope tracking circuit is further configured to generate the control signal based on an average value of the supply voltage during a predefined time interval.

11. The circuit of claim 10 , wherein the envelope tracking circuit is configured to generate a control signal indicating a lower desired supply voltage than the instantaneous control signal, if the average value of the supply voltage is higher than a reference value for the supply voltage.

12. The circuit of claim 11 , wherein the reference value for the supply voltage is different for different output power levels of the amplifier.

13. The circuit of claim 1 , wherein the envelope tracking circuit is configured to generate a further control signal based on the bandwidth of the baseband signal, and wherein the circuit further comprises a pre-distortion circuit configured to supply, to the amplifier, a modified baseband signal based on the further control signal.

14. The circuit of claim 1 , wherein the envelope tracking circuit is further configured to generate the control signal based on a power of the baseband signal.

15. A control circuit for controlling a power supply supplying a variable supply voltage to an amplifier, the amplifier generating a radio frequency signal based on a baseband signal, wherein the control circuit is configured to mitigate a bandwidth dependent gain variation of the power supply by generating a control signal based on a compensation factor corresponding to a bandwidth of the baseband signal, and supplying the control signal to the power supply.

16. A method for generating a radio frequency signal depending on a baseband signal using an amplifier, comprising:

generating a control signal for a power supply based on a compensation factor corresponding to a bandwidth of the baseband signal to compensate for a bandwidth dependent gain of the power supply;

supplying the control signal to the power supply;

generating a variable supply voltage based on the control signal using the power supply; and

supplying the variable supply voltage to the amplifier,

wherein the control signal indicates a desired supply voltage.

17. The method of claim 16 , wherein generating the control signal for the power supply and supplying the control signal to the power supply comprises:

generating a first control signal for the power supply for a first bandwidth of the baseband signal;

supplying the first control signal to the power supply;

providing a second control signal for the power supply for a higher second bandwidth of the baseband signal, the second control signal indicating a higher desired supply voltage than the first control signal; and

supplying the second control signal to the power supply.

18. The method of claim 16 , wherein the method further comprises calculating the bandwidth of the baseband signal.

19. The method of claim 18 , wherein the radio frequency signal is a radio frequency signal for Long Term Evolution communications comprising a number of allocated resource blocks, and wherein calculating the bandwidth of the baseband signal comprises calculating the bandwidth of the baseband signal based on the number of allocated resource blocks.

20. The method of claim 16 , wherein generating the control signal is further based on a power of the baseband signal.

21. The method of claim 16 , wherein generating the control signal further comprises generating the control signal based on a frequency of the radio frequency signal.

22. The method of claim 21 , wherein the radio frequency signal is a radio frequency signal for Long Term Evolution communications comprising a plurality of allocated resource blocks at different frequencies of the radio frequency signal, and wherein generating the control signal further comprises generating the control signal based on a frequency related to the different frequencies of the plurality of allocated resource blocks.

23. The method of claim 16 , wherein providing the control signal further comprises generate the control signal based on an average value of the supply voltage during a predefined time interval.

24. The method of claim 16 , wherein the method further comprises:

generating a further control signal for a pre-distortion circuit based on the bandwidth of the baseband signal, and

supplying, to the amplifier, a modified baseband signal based on the further control signal using the pre-distortion circuit.

25. A method for controlling a power supply supplying a variable supply voltage to an amplifier, the amplifier generating a radio frequency signal based on a baseband signal, wherein the method comprises mitigating a bandwidth dependent gain variation of the power supply by generating a control signal based on a compensation factor corresponding to a bandwidth of the baseband signal and supplying the control signal to the power supply.