Calibrating a power amplifier such as in a remote unit in a wireless distribution system (WDS)

1. A method for calibrating an amplifier, comprising:

providing a plurality of bias signal combinations to an amplifier configured to amplify an input signal to generate an output signal, wherein each of the plurality of bias signal combinations comprises a respective first bias signal and a respective second bias signal to be provided to the amplifier for controlling a first amplifier performance parameter and a second amplifier performance parameter in the output signal, respectively;

receiving a plurality of performance indication signals comprising a plurality of measurements corresponding to the plurality of bias signal combinations, respectively, wherein each of the plurality of measurements comprises the first amplifier performance parameter and the second amplifier performance parameter;

ranking the plurality of measurements;

determining a selected bias signal combination among the plurality of bias signal combinations corresponding to a selected ranked measurement among the plurality of measurements; and

controlling the amplifier to operate based on the selected bias signal combination.

2. The method of claim 1 , further comprising:

representing the respective first bias signal by a first digital word; and

representing the respective second bias signal by a second digital word.

3. The method of claim 1 , further comprising:

receiving a modulated broadband input signal, wherein the modulated broadband input signal comprises a first signal in a first signal frequency and a second signal in a second signal frequency; and

generating a modulated broadband output signal, wherein the modulated broadband output signal comprises the first signal and the second signal.

4. The method of claim 1 , further comprising:

receiving the input signal from a signal generator communicatively coupled to the amplifier; and

providing the output signal to a spectrum analyzer communicatively coupled to the amplifier and a control circuit.

5. The method of claim 4 , further comprising:

generating the plurality of measurements corresponding to the plurality of bias signal combinations, respectively;

generating the plurality of performance indication signals comprising the plurality of measurements in association with the plurality of bias signal combinations, respectively; and

providing the plurality of performance indication signals to the control circuit.

6. The method of claim 1 , further comprising controlling a third-order intermodulation (IMD3) and an adjacent channel power ratio (ACPR) in the output signal based on the respective first bias signal and the respective second bias signal.

7. A method for calibrating an amplifier, comprising:

receiving a modulated broadband input signal, wherein the modulated broadband input signal comprises a first signal in a first signal frequency and a second signal in a second signal frequency;

providing a plurality of bias signal combinations to an amplifier configured to amplify an input signal to generate an output signal, wherein each of the plurality of bias signal combinations comprises a respective first bias signal and a respective second bias signal to be provided to the amplifier for controlling a first amplifier performance parameter and a second amplifier performance parameter in the output signal, respectively;

receiving a plurality of performance indication signals comprising a plurality of measurements corresponding to the plurality of bias signal combinations, respectively, wherein each of the plurality of measurements comprises the first amplifier performance parameter and the second amplifier performance parameter;

ranking the plurality of measurements; and

determining a selected bias signal combination among the plurality of bias signal combinations corresponding to a selected ranked measurement among the plurality of measurements.

8. The method of claim 7 , further comprising generating a modulated broadband output signal, wherein the modulated broadband output signal comprises the first signal and the second signal.

9. The method of claim 8 , further comprising:

representing the respective first bias signal by a first digital word; and

representing the respective second bias signal by a second digital word.

10. The method of claim 7 , further comprising receiving the input signal from a signal generator communicatively coupled to the amplifier.

11. The method of claim 10 , further comprising providing the output signal to a spectrum analyzer communicatively coupled to the amplifier and a control circuit.

12. The method of claim 11 , further comprising:

generating the plurality of measurements corresponding to the plurality of bias signal combinations, respectively;

generating the plurality of performance indication signals comprising the plurality of measurements in association with the plurality of bias signal combinations, respectively; and

providing the plurality of performance indication signals to the control circuit.

13. The method of claim 7 , further comprising controlling a third-order intermodulation (IMD3) and an adjacent channel power ratio (ACPR) in the output signal based on the respective first bias signal and the respective second bias signal.

14. A method for calibrating an amplifier, comprising:

providing a plurality of bias signal combinations to an amplifier configured to amplify an input signal to generate an output signal, wherein each of the plurality of bias signal combinations comprises a respective first bias signal and a respective second bias signal to be provided to the amplifier for controlling a first amplifier performance parameter and a second amplifier performance parameter in the output signal, respectively;

receiving a plurality of performance indication signals comprising a plurality of measurements corresponding to the plurality of bias signal combinations, respectively, wherein each of the plurality of measurements comprises the first amplifier performance parameter and the second amplifier performance parameter;

ranking the plurality of measurements;

determining a selected bias signal combination among the plurality of bias signal combinations corresponding to a selected ranked measurement among the plurality of measurements; and

controlling a third-order intermodulation (IMD3) and an adjacent channel power ratio (ACPR) in the output signal based on the respective first bias signal and the respective second bias signal.

15. The method of claim 14 , further comprising receiving the plurality of measurements each comprising a respective IMD3 and a respective ACPR of the output signal.

16. The method of claim 14 , further comprising for each measurement among the plurality of measurements:

calculating a respective IMD3 margin between a predefined IMD3 threshold and the respective IMD3;

calculating a respective ACPR margin between a predefined ACPR threshold and the respective ACPR;

scaling the respective IMD3 margin based on a predefined IMD3 scale factor to generate a respective scaled IMD3 margin;

scaling the respective ACPR margin based on a predefined ACPR scale factor to generate a respective scaled ACPR margin;

determining a respective minimal margin corresponding to a smaller scaled margin between the respective scaled IMD3 margin and the respective scaled ACPR margin; and

storing the selected bias signal combination in association with the respective minimal margin.