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

An optical fiber-based wireless distribution system (WDS), comprising:

• a plurality of cables including at least one optical communications medium;
• and
• a plurality of remote units comprising optical-to-electrical converters and configured to:
• receive and convert a plurality of downlink digital communications signals into a plurality of downlink radio frequency (RF) communications signals for distribution to client devices;
• and
• receive a plurality of uplink RF communications signals from the client devices and convert the plurality of uplink RF communications signals into a plurality of optical uplink digital communications signals;
• wherein at least one selected remote unit among the plurality of remote units comprises a power amplifier calibration circuit, the power amplifier calibration circuit comprising:
• a power amplifier comprising a signal input, a signal output, a first bias signal input, and a second bias signal input, wherein the power amplifier is configured to:
• receive an input signal having a first power at the signal input;
• receive a first bias signal at the first bias signal input;
• receive a second bias signal at the second bias signal input;
• amplify the input signal to generate an output signal having a second power higher than the first power at the signal output;
• and
• control a first power amplifier performance parameter and a second power amplifier performance parameter in the output signal based on the first bias signal and the second bias signal;
• and
• a control circuit configured to:
• provide a plurality of bias signal combinations to the power amplifier, 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 first bias signal input and the second bias signal input of the power amplifier, respectively;
• receive 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 power amplifier performance parameter and the second power amplifier performance parameter;
• rank the plurality of measurements based on a ranking criterion;
• and
• determine a selected bias signal combination among the plurality of bias signal combinations corresponding to a selected ranked measurement among the plurality of measurements.

A communications system, comprising:

• a plurality of remote units comprising optical-to-electrical converters and configured to:
• convert a plurality of downlink digital communications signals into a plurality of downlink radio frequency (RF) communications signals;
• and
• receive a plurality of uplink RF communications signals and convert the plurality of uplink RF communications signals into a plurality of uplink digital communications signals;
• and
• a central unit configured to:
• distribute the plurality of downlink digital communications signals to the plurality of remote units;
• and
• receive the plurality of uplink digital communications signals from the plurality of remote units,
• wherein the central unit comprises at least one electrical-to-optical converter configured to convert the plurality of downlink digital communications signals into optical signals;
• wherein at least one selected remote unit among the plurality of remote units comprises a power amplifier calibration circuit, the power amplifier calibration circuit comprising:
• a power amplifier comprising a signal output, a first bias signal input, and a second bias signal input, wherein the power amplifier is configured to:
• receive an input signal having a first power;
• receive a first bias signal at the first bias signal input;
• receive a second bias signal at the second bias signal input;
• amplify the input signal to generate an output signal having a second power higher than the first power at the signal output;
• and
• control a first power amplifier performance parameter and a second power amplifier performance parameter in the output signal based on the first bias signal and the second bias signal;
• and
• a control circuit configured to:
• provide a plurality of bias signal combinations to the power amplifier, 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 first bias signal input and the second bias signal input of the power amplifier, respectively;
• receive 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 power amplifier performance parameter and the second power amplifier performance parameter;
• rank the plurality of measurements based on a predefined ranking criterion;
• and
• determine a selected bias signal combination among the plurality of bias signal combinations corresponding to a selected ranked measurement among the plurality of measurements.