New De-Embedding Techniques for PCB Transmission-Line Characterization

Commercially available transmission-line characterization techniques within the PCB industry often face challenges in de-embedding of launching vias, where a long via or via stub can significantly impact the results at high frequencies. In this paper, VNA measurements with various de-embedding methods, including those that utilize only one 2X-thru calibration standard are studied. Commercial tools and a new method with an alternative algorithm are used to remove the test fixture and via from the measurement. Test boards were built with varying lengths of transmission lines, and in different routing layers. Excellent de-embedded results are achieved up to 30 GHz. The 2X-thru de-embedding methodology significantly simplified the test-fixture design, and the de-embedding procedures