it refers to,
Digital Predistortion Control (DPD) (AD9375 only)
The DPD is a feature available on the AD9375 that enables users to achieve higher power amplifier (PA) efficiency while still meeting adjacent channel leakage ratio (ACLR) requirements in the Tx signal chain for compliance with 3GPP and European Telecommunications Standards Institute (ETSI) standards for LTE and other technologies. The DPD works on the principle of predistorting the Tx data to cancel distortion caused by PA compression.
For more details please consult the AD9371/AD9375 System Development User Guide UG-992
Could you point me to the UG-992 document?