A fabrication-motivated model for improving characteristic impedance extraction

Published

February 25, 2026

Author(s)

Florian Bergmann, Nicholas Jungwirth, Nicholas Derimow, Bryan Bosworth, Meagan Papac, Eric Marksz, Tomasz Karpisz, Jerome Cheron, Vincenzo St. George, Angela Stelson, Benjamin Jamroz, Christian Long, Nathan Orloff

Abstract

The characteristic impedance and the propagation constant fully describe a transmission line. The multiline Thru-Reflect-Line algorithm provides a direct measurement of the propagation constant and corrects measurement data to a reference impedance equal to the unknown characteristic impedance. Methods to extract this characteristic impedance may use a combination of additional microwave measurements, dc measurements, and simulations. However, simulation accuracy relies on knowledge of the physical transmission line geometry. In this work, we investigated a simple fabrication-motivated model to improve the accuracy of simulation-based impedance extraction. Our model self-consistently perturbs the nominal geometry of the conductors to maximize agreement with the impedance extracted using measurement-based techniques. We tested our model by comparing its prediction of the cross-sectional geometry to scanning electron microscopy measurements. Our model enables self-consistent on-wafer impedance extraction and offers a path towards traceable on-wafer impedance.

Citation

IEEE Transactions on Microwave Theory and Techniques

Pub Type

Journals

Download Paper

Local Download

Keywords

Characteristic impedance, on-wafer, transmission lines, photolithography, distributed circuit parameters, finite-element simulations

Citation

Bergmann, F. , Jungwirth, N. , Derimow, N. , Bosworth, B. , Papac, M. , Marksz, E. , Karpisz, T. , Cheron, J. , St. George, V. , Stelson, A. , Jamroz, B. , Long, C. and Orloff, N. (2026), A fabrication-motivated model for improving characteristic impedance extraction, IEEE Transactions on Microwave Theory and Techniques, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960872 (Accessed April 8, 2026)