The patented RAPID load-pull concept employs the latest in PXI test instrumentation. The technique employs a ‘quasi closed loop’ approach, this approach maintains the speed of a closed loop active load-pull system but removes the inherent stability issues that limit their application. Here the output signal from the device is fed to a circulator, and passed to the PXI chassis where the signal is down-converted, modified to set the desired impedance, unconverted and then injected back to test device to set an invariant impedance. As there is feedback any change in the device output, such as a change in drive level, this is automatically compensated for in the feedback signal. The result is extremely fast impedance changes and a super fast calibration process.
The impedance is presented by taking the b2 output from the device and using the control and calibration information, presenting back to the device the modified a2 wave.
The RAPID solution can be added to a standard Active or Hybrid load pull system to enable ultra fast measurements to be undertaken.