A $W$-Band On-Wafer Active Load–Pull System Based on Down-Conversion Techniques

Abstract

A new W-band active load-pull system is presented. It is the first load-pull system to implement a 94 GHz load by means of an active loop exploiting frequency conversion techniques. The active loop configuration demonstrates a number of advantages that overcome the typical limitations of W-band passive tuners or conventional active open-loop techniques in a cost-effective way: load reflection coefficients Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> as high as 0.95 in magnitude can be achieved at 94 GHz, thus providing a nearly full coverage of the Smith chart. Possible applications of the setup include technology assessment, large-signal device model verification at sub-terahertz frequencies, and W-band monolithic microwave integrated circuit design and characterization. The availability of direct and accurate load-pull measurements at W-band should prove an asset in the development of sub-terahertz integrated circuits. First measurements performed on high-performance InP double heterojunction bipolar transistors and GaN high electron-mobility transistors are presented.