Load-pull suppliers are using the PXI architecture and hardware software design tools to help customers simplify power amplifier characterization during development, pre-production, and production testing. (Source: National Instruments)
The concept of load pull may not be that clear to many Design News readers since, while it does sort of have a mechanical equivalent, it has not been talked about by this name outside of the RF amplifier design realm very much.
Load pull is the effect on the amplifier output caused by chyanges in the downstream load impedance driven by the amplifier's output power. It may often be quite nonlinear, which makes modeling a bit more challenging. Also, the effect may work in both directions, making evaluation and analysis more complex and challenging.