Method and apparatus for improving efficiency and distortion leakage in a wireless power amplifier
View Patent ↗A wireless communication system ( 400 ) for power amplification of an input signal includes a power amplifier ( 404 ) operable to amplify a data signal ( 405 ). An envelope generator 408 or detector is operable to determine an envelope signal ( 410 ) from the data signal. A tracking power supply or other power supply control circuit ( 409 ) is operable to control a supply voltage of the power amplifier with the envelope signal. An allocation manager ( 441 ) is operable to determine a resource block allocation within a channel for the data signal. A delay circuit ( 443 ) is operable to insert a delay ( 550 ) between the envelope signal and the data signal as a function of the resource block allocation within the channel, thereby intentionally causing unbalanced leakage about the resource block allocation. Increased leakage on one side of the allocation results in improved leakage on the other side.
1. A method for controlling a power supply voltage of a power amplifier in a power amplifier module, comprising:
determining an envelope signal based upon a data signal;
determining a resource block within a channel on which the data signal will be transmitted;
delaying one of the envelope signal or the data signal as a function of a resource block allocation within the channel; and
after the delaying, controlling a power supply of the power amplifier with the envelope signal and applying the data signal to the power amplifier to cause asymmetrical leakage about the resource block.
2. The method of claim 1 , further comprising adjusting the delaying as a function of changes to the resource block allocation within the channel.
3. The method of claim 1 , wherein the controlling further comprises controlling one of a load, bias, or supply voltage of the power amplifier with the envelope signal to improve efficiency of the power amplifier.
4. The method of claim 1 , wherein the controlling comprises applying the envelope signal to a tracking power supply of the power amplifier.
5. The method of claim 1 , further comprising determining the function of resource block allocation within the channel by accessing a look-up table.
6. The method of claim 5 , wherein the look-up table comprises a plurality of delay values, each delay value corresponding to an allocation of the resource block within the channel.
7. The method of claim 1 , wherein the delaying increases leakage within the channel and reduces leakage outside the channel.
8. The method of claim 1 , wherein the delaying increases leakage in higher frequency resource blocks and reduces leakage in lower frequency resource blocks.
9. The method of claim 1 , wherein the delaying increases leakage in lower frequency resource blocks and reduces leakage in higher frequency resource blocks.
10. The method of claim 1 , wherein the resource block comprises a transmit resource block and has associated therewith a corresponding receive resource block, wherein the delaying reduces leakage in the corresponding receive resource block and increases leakage on resource blocks other than the corresponding receive resource block.
11. A system for power amplification of an input signal, comprising:
a power amplifier operable to amplify a data signal;
an envelope detector operable to determine an envelope signal from the data signal;
a tracking power supply operable to control a supply voltage of the power amplifier with the envelope signal;
an allocation manager operable to determine a resource block allocation within a channel for the data signal; and
a delay circuit operable to insert a delay between the envelope signal and the data signal as a function of the resource block allocation within the channel, thereby causing unbalanced leakage about the resource block allocation.
12. The system of claim 11 , wherein the function of the resource block allocation within the channel comprises a measure of a closeness of the resource block allocation to an edge of the channel.
13. The system of claim 12 , wherein the unbalanced leakage comprises increased leakage within the channel and reduced leakage outside the channel.
14. The system of claim 11 , wherein the function of the resource block allocation comprises a measure of a closeness of the resource block allocation to a public safety band.
15. The system of claim 14 , wherein the unbalanced leakage comprises reduced leakage in the public safety band and increased leakage in resource blocks of the channel other than the public safety band.
16. The system of claim 11 , further comprising a memory, operable with the allocation manager, wherein the memory stores a look-up table comprising a plurality of delay values, each delay value corresponding to an allocation of one or more resource blocks within the channel.
17. A method of controlling spectral regrowth about a resource allocation within a wireless transmission channel, comprising inserting a delay between a time varying supply voltage applied to a power amplifier as a first function of a data signal to increase leakage within the wireless transmission channel and reduce leakage outside the wireless transmission channel, wherein the delay is a second function of the resource allocation within the wireless transmission channel.
18. The method of claim 17 , further comprising increasing leakage on resources of the wireless transmission channel other than those being used by the power amplifier.
19. The method of claim 17 , further comprising determining the delay by selecting a delay value from a plurality of delay values, where each delay value corresponds to a predefined allocation of the one or more resource blocks within the wireless transmission channel.