Direct sampling for digital pre-distortion calibration

A multiple input multiple output (MIMO) transceiver configured for digital pre-distortion (DPD) calibration, the MIMO transceiver comprising:

• a first communication chain configured to generate a first signal at a first frequency, the first communication chain comprising a first pre-distorter circuit configured to accept first pre-distortion parameters to pre-distort signals and a first power amplifier (PA) configured to amplify the signals of the first communication chain;
• a DPD calibration chain configured to receive the first signal at the first frequency, the DPD calibration chain comprising:
• a data converter configured to perform operations comprising:
• sampling the first signal at the first frequency using a sampling rate based on a baseband frequency, the baseband frequency being lower than the first frequency;
• and
• generating a sample signal at the baseband frequency based on the sampling of the first signal;
• and
• a buffer configured to buffer the sample signal at the baseband frequency;
• a DPD circuit configured to calibrate the first pre-distortion parameters based on the buffered sample signal to compensate for non-linearity in amplification provided by the first PA of the first communication chain;
• and
• a second communication chain configured to transmit a second signal at the first frequency, the second communication chain comprising:
• a second pre-distorter circuit configured to accept second pre-distortion parameters to pre-distort signals;
• and
• a second PA configured to amplify the signals of the second communication chain;
• wherein the DPD calibration chain is further configured to receive a combined signal that includes the first signal and the second signal at the first frequency;
• and
• wherein the DPD circuit is further configured to:
• isolate the first signal and the second signal from the combined signal;
• and
• calibrate the second pre-distortion parameters based on the second signal to compensate for non-linearity in amplification provided by the second PA of the second communication chain.

A multiple input multiple output (MIMO) transceiver configured for digital pre-distortion (DPD) calibration, the MIMO transceiver comprising:

• a first communication chain configured to generate a first signal at a first frequency, the first communication chain comprising a first pre-distorter circuit configured to accept first pre-distortion parameters to pre-distort signals and a first power amplifier (PA) configured to amplify the signals of the first communication chain;
• a DPD calibration chain configured to receive the first signal at the first frequency, the DPD calibration chain comprising:
• a data converter configured to perform operations comprising:
• sampling the first signal at the first frequency using a sampling rate based on a baseband frequency, the baseband frequency being lower than the first frequency;
• and
• generating a sample signal at the baseband frequency based on the sampling of the first signal;
• and
• a buffer configured to buffer the sample signal at the baseband frequency;
• a DPD circuit configured to calibrate the first pre-distortion parameters based on the buffered sample signal to compensate for non-linearity in amplification provided by the first PA of the first communication chain;
• and
• a second communication chain configured to transmit a second signal at the first frequency, the second communication chain comprising:
• a second pre-distorter circuit configured to accept second pre-distortion parameters to pre-distort signals;
• and
• a second PA configured to amplify the signals of the second communication chain;
• wherein:
• the DPD calibration chain is further configured to receive the second signal at the first frequency;
• the DPD circuit is further configured to calibrate the second pre-distortion parameters based on the second signal to compensate for non-linearity in amplification provided by the second PA of the second communication chain;
• and
• the MIMO transceiver further comprises a chain selector circuit configured to selectively provide a control signal to the first communication chain and the second communication chain, the control signal indicating which of the first communication chain and the second communication chain are to generate corresponding signals.

A multiple input multiple output (MIMO) transceiver configured for digital pre-distortion (DPD) calibration, the MIMO transceiver comprising:

• a first communication chain configured to generate a signal at a first frequency, the first communication chain comprising a pre-distorter circuit configured to accept pre-distortion parameters to pre-distort signals and a power amplifier (PA) configured to amplify the signals of the first communication chain;
• a DPD calibration chain configured to receive the signal at the first frequency, the DPD calibration chain comprising:
• a data converter configured to perform operations comprising:
• sampling the signal at the first frequency using a sampling rate based on a baseband frequency, the baseband frequency being lower than the first frequency;
• and
• generating a sample signal at the baseband frequency based on the sampling of the signal;
• and
• a buffer configured to buffer the sample signal at the baseband frequency;
• and
• a DPD circuit configured to calibrate the pre-distortion parameters based on the buffered sample signal to compensate for non-linearity in amplification provided by the PA of the first communication chain;
• wherein the DPD circuit is further configured to compare a value of a power level of the buffered sample signal to a value of a power level of an expected signal, the pre-distortion parameters being calibrated based on a difference between the values of the power levels of the buffered sample signal and the expected signal.