A general-purpose system for fast, automated acquisition of the S-parameters of three-port components is described, which is suitable for accurate device characterization as well as RF testing of three-port circuits in a production environment. Though based on conventional, nonrepeatable, electromechanical switches, the system achieves state of the art accuracy for on-wafer measurements by means of suitable hardware design and the application of time-domain gating. The system is applied to the characterization of MMIC (monolithic microwave IC) T-coils and single-pole double-throw (SPDT) switches. The bandwidth is now limited to 20 GHz but can be easily upgraded to 26.5 GHz by replacing one of the switches. Acquisition of the corrected S-parameters takes about 15 seconds (51 frequency points) with a HP 9000/330 controller.
