Predistortion circuit, method for generating a predistorted baseband signal, control circuit for a predistortion circuit, method to determine parameters for a predistortion circuit, and apparatus and method for predistorting a baseband signal

1. A predistortion circuit for a wireless transmitter, the predistortion circuit comprising:

a signal input configured to receive a baseband signal; and

a predistorter comprising a plurality of predistortion sub-circuits, each predistortion sub-circuit configured to perform corresponding predistortion computations, the predistorter configured to generate a predistorted baseband signal using the baseband signal and a predistorter configuration, wherein the predistorter configuration is selected from among a first predistorter configuration and a second predistorter configuration by selectively activating a corresponding unique combination of predistortion sub-circuits based at least on which one of an Average Power Tracking Mode and an Envelope Tracking mode is a current operating mode of a power amplifier of the wireless transmitter.

2. The predistortion circuit of claim 1 , wherein the first predistorter configuration performs a first predistortion function and wherein the second predistorter configuration performs a second predistortion function.

3. The predistortion circuit of claim 1 , wherein:

a first number of predistortion sub-circuits are active in the first predistorter configuration; and

a second number of predistortion sub-circuits are active in the second predistorter configuration.

4. The predistortion circuit of claim 3 , wherein the second number is higher than the first number.

5. The predistortion circuit of claim 3 , wherein:

the first number of predistortion sub-circuits are configured to operate at a first rate;

the second number of predistortion sub-circuits are configured to operate at a second rate; and

the second rate is higher than the first rate.

6. The predistortion circuit of claim 5 , further comprising:

a sample rate converter configured to match an output of the first number of predistortion sub-circuits to the second rate to generate a rate matched output of the first number of predistortion sub-circuits.

7. The predistortion circuit of claim 6 , further comprising:

a combination circuit configured to combine an output of the second number of predistortion sub-circuits and the rate matched output of the first number of predistortion sub-circuits.

8. The predistortion circuit of claim 1 , further comprising:

a configuration handling circuit configured to select the predistorter configuration further based on an operating characteristic of the wireless transmitter.

9. The predistortion circuit of claim 8 , wherein the operating characteristic comprises at least one of an output power range, a peak-to-average power ratio of the baseband signal, a modulation scheme used to generate the baseband signal, or a matching condition of an antenna.

10. The predistortion circuit of claim 8 , wherein the operating characteristic comprises at least one of a transmit bandwidth, a transmit band, a transmit frequency range within the transmit band, a number of transmit clusters in a frequency domain, a frequency separation between the transmit clusters, or a bandwidth of each transmit cluster.

11. The predistortion circuit of claim 8 , wherein the operating characteristic comprises an acceptable spectral mask.

12. The predistortion circuit of claim 8 , wherein the configuration handling circuit further comprises:

an input interface configured to receive a feedback signal depending on an output of the power amplifier, wherein the configuration handling circuit is further configured to select the predistorter configuration further based on the feedback signal.

13. A method for generating a predistorted baseband signal for a wireless transmitter, the method comprising:

selecting a predistorter configuration from among a first predistorter configuration and a second predistorter configuration by selectively activating a corresponding unique combination of predistortion sub-circuits from a plurality of predistortion sub-circuits based at least on which one of an Average Power Tracking Mode and an Envelope Tracking mode is a current operating mode of a power amplifier of the wireless transmitter, wherein each predistortion sub-circuit performs corresponding predistortion computations; and

generating the predistorted baseband signal using a baseband signal and the selected predistorter configuration.

14. The method of claim 13 , further comprising:

performing a first predistortion function in the first predistorter configuration; and

performing a second predistortion function in the second predistorter configuration.

15. The method of claim 13 , further comprising:

using a first number of predistortion sub-circuits in the first predistorter configuration; and

using a second number of predistortion sub-circuits in the second predistorter configuration.

16. The method of claim 15 , further comprising:

operating the first number of predistortion sub-circuits at a first rate; and

operating the second number of predistortion sub-circuits at a second rate;

wherein the first rate is higher than the second rate.

17. The method of claim 16 , further comprising:

matching an output of the first number of predistortion sub-circuits to the second rate to generate a rate matched output of the first number of predistortion sub-circuits.

18. The method of claim 17 , further comprising:

combining an output of the second number of predistortion sub-circuits and the rate matched output of the first number of predistortion sub-circuits.

19. The method of claim 15 , wherein the second number is higher than the first number.

20. The method of claim 13 , further comprising:

selecting the predistorter configuration further based on an operating characteristic of the wireless transmitter.