A digital, PXI-based active load-pull tuner to maximize throughput of a load-pull test bench

This paper presents a cost effective, digital, PXI-based active load-pull tuner architecture. This allows for significant reduction in test time, without compromising measurement quality or control. We will demonstrate for the first time, ability to compensate for the non-linear behavior of the loop amplifier within the active loop, thus moving from a proof of concept architecture to one that is applicable to real-world applications. The calibration process required for accurate reflection coefficient setting is presented, as well as analysis of the long-term reflection coefficient stability. It is shown how the RF bandwidth of the architecture can be increased through the use of up/down convertors directly in the feedback loop, with testing completed at 17GHz. A direct comparison in measurement time between passive, active open-loop and the digital architecture is also presented, showing the digital tuner as much as 14 times faster than a passive tuner for a fixed power impedance grid, using the same measurement receiver and setup.