First Comparison of Active and Passive Load Pull at W-Band

GaN W-band devices have shown remarkable power performances using passive load pull measurements. However, as the device peripheries increase to provide higher power from a single cell, the available matching range from passive load pull becomes a greater limiting factor. Switching to active load pull, the matching range can cover the entire Smith chart, given sufficient drive power. In this work, the design of a high-power W-band on-wafer active load pull is shown, along with some of the configuration choices and associated tradeoffs in system performance and flexibility. N-polar GaN HEMT devices were measured in this setup and a passive load pull system to compare and qualify the new active load pull system configuration.