Accurate characterization of PCB transmission lines for high speed interconnect

Accurate PCB transmission-line characterization can be challenging due to the effect of test fixtures and launching vias, etc. In this paper, VNA measurements with innovative de-embedding approaches, including those that utilize only one “2X-Thru” calibration standard are studied. The 2X-Thru de-embedding method is first shown to be correlated to existing TRL calibration method. Test boards built with varying lengths of transmission lines routed on different layers were then characterized with the new de-embedding method. Excellent de-embedded results are achieved for frequencies up to 30 GHz.