Envelope tracking measurements are used to evaluate the improvements of power efficiency and output signal performance after using envelope tracking. For a PA, envelope tracking and digital pre-distortion can be used together. In this example, only envelope tracking is applied to the PA under test using PXI VSA/VSG/M320xA AWG. From concept of view, it is similar to envelope tracking done with bench top instruments. The only difference is the hardware used in this example.
The whole measurement process includes the following three parts.