1GP104

Digital Pre-Distortion

The SMW has to perform several iterations (level measurement and adjustment) to approach the RF output level set by the user. This process is a trade-off between speed, i.e. number of iterations and level accuracy, i.e. remaining level error. The user can therefore define the maximum number of iterations to perform. In addition, he can define the maximum allowable level error. The iteration process stops when the defined number of iterations is reached. It will stop earlier if the defined maximum level error is already reached. (If the defined number of iterations is not enough to reach the desired level error, the user needs to increase the number of iterations.)

The actual RF level parameters after DPD are displayed.

8.2.2 DPD Interaction with ET

When digital pre-distortion is used in combination with envelope tracking, the user can set if the envelope signal is calculated from the original baseband signal or from the pre-distorted baseband signal.

This selection can be made in the

“I/Q Analog Outputs” menu:

Original baseband signal

Pre-distorted baseband signal

1GP104_1E Rohde & Schwarz Envelope Tracking and Digital Pre-Distortion Test Solution for RF Amplifiers 33