Method and apparatus for a nonlinear feedback control system

1. A method for pre-distorting a nonlinear device, comprising:

generating a first output signal from the nonlinear device;

detecting a first plurality of feedback data values from the first output signal;

extrapolating a current variation value from the first plurality of feedback data values;

deriving a first pre-distortion value from the first plurality of feedback data values using the current variation value;

generating a first input signal based on the first pre-distortion value; and

providing the first input signal to the nonlinear device;

extrapolation of the current variation value being bypassed by using a previous variation value if a noise level of at least one of the first plurality of feedback data values is above a threshold noise level.

2. The method for pre-distorting a nonlinear device as in claim 1 , further comprising:

generating a second output signal from the nonlinear device;

detecting a second plurality of feedback data values from the second output signal;

deriving a second pre-distortion value from the second plurality of feedback data values;

generating a second input signal based on the second pre-distortion value; and

providing the second input signal to the nonlinear device.

3. The method for pre-distorting a nonlinear device as in claim 1 , further comprising:

using an open loop pre-distortion value before detecting the first plurality of feedback data values from the first output signal;

generating an open loop input signal based on the open loop pre-distortion value; and

providing the open loop input signal to the nonlinear device.

4. The method for pre-distorting a nonlinear device as in claim 1 , wherein deriving the first pre-distortion value further comprises:

validating the first plurality of feedback data values.

5. A method for pre-distorting a nonlinear device, comprising:

generating an output signal from the nonlinear device;

detecting a plurality of feedback data values from the output signal;

extrapolating a variation value from the plurality of feedback data values if an expected output signal value is beyond a range of feedback data values already detected and if a noise level of at least one of the plurality of feedback values is below a threshold;

calculating a pre-distortion value using the variation value;

generating an input signal based on the pre-distortion value;

providing the input signal to the nonlinear device;

processing the pre-distortion value;

storing the processed pre-distortion value in a look-up-table; and

storing a feedback data value corresponding to the processed pre-distortion value in the look-up-table.

6. The method for pre-distorting a nonlinear device as in claim 5 , further comprising:

using an open loop pre-distortion value before detecting the plurality of feedback data values from the output signal;

generating an open loop input signal based on the open loop pre-distortion value; and

providing the open loop input signal to the nonlinear device.

7. The method for pre-distorting a nonlinear device as in claim 5 , further comprising:

generating an interpolated variation value if the expected output signal value is within a range of feedback data values already detected;

calculating an interpolated pre-distortion value using the interpolated variation value;

generating an interpolated input signal based on the interpolated pre-distortion value; and

providing the interpolated input signal to the nonlinear device.

8. The method for pre-distorting a nonlinear device as in claim 5 , further comprising:

discontinuing the extrapolation of the variation value and the calculation of the pre-distortion value after a desired number of the processed pre-distortion values are stored in the look-up-table;

using at least one stored processed pre-distortion value and at least one corresponding stored feedback data value to generate an interpolated input signal; and

providing the interpolated input signal to the nonlinear device.

9. The method for pre-distorting a nonlinear device as in claim 8 , further comprising:

restarting the extrapolation of the variation value and the calculation of the pre-distortion value;

wherein the pre-distortion value is used to generate the input signal.

10. A nonlinear feedback control system, comprising:

a nonlinear device having a first input and a first output and configured to generate a first output signal;

a detection stage in communication with the first output of the nonlinear device and configured to detect a first plurality of feedback data values from the first output signal;

a derivation stage in communication with the detection stage and configured to derive a first pre-distortion value from the first plurality of feedback data values, said derivation stage comprising a closed loop stage configured to extrapolate a current variation value from the first plurality of feedback data values, and calculate the first pre-distortion value using the current variation value; and

the derivation stage being in communication with the first input of the nonlinear device to generate a first input signal based on the first pre-distortion value and provide the first input signal to the nonlinear device;

extrapolation of the current variation value being bypassed by using a previous variation value if a noise level of at least one of the first plurality of feedback data values is above a threshold noise level.

11. The nonlinear feedback control system as in claim 10 , wherein the nonlinear device is a power amplifier.

12. The nonlinear feedback control system as in claim 10 , further comprising:

a reference signal stage in communication with the derivation stage;

wherein the reference signal stage includes a phase or amplitude signal.

13. The nonlinear feedback control system as in claim 10 , further comprising:

the nonlinear device having a second input and second output;

the detection stage in communication with the second output of the nonlinear device; and

the derivation stage in communication with the second input of the nonlinear device.

14. The nonlinear feedback control system as in claim 10 , wherein the derivation stage further comprises:

an open loop stage connected in parallel with the closed loop stage.

15. The nonlinear feedback control system as in claim 10 , wherein the closed loop stage further comprises:

an interpolation stage.