Skip to main content

NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

A 4:1 transmission-line impedance transformer for broadband superconducting circuits

Published

Author(s)

Leonardo M. Ranzani, Lafe F. Spietz, Jose A. Aumentado, Zoya Popovic

Abstract

We present a 4 : 1 superconducting transmission-line impedance transformer for cryogenic applications. The device transforms 25 {Ω} in the coplanar waveguide to 6.25 {Ω} in the microstrip and is designed to operate at 20 mK. Calibrated measurements in a dilution refrigerator demonstrate a -3 dB bandwidth from 1.6 to 13 GHz. In a modified Ruthroff design, a small capacitor is integrated at the input as a direct-current block, making it suitable for biasing and matching to low-impedance active circuits, such as superconducting quantum interference device (SQUID) amplifiers.
Citation
IEEE Transactions on Applied Superconductivity
Volume
22
Issue
5

Keywords

Superconducting microwave devices, impedance matching, transformers

Citation

Ranzani, L. , Spietz, L. , Aumentado, J. and Popovic, Z. (2012), A 4:1 transmission-line impedance transformer for broadband superconducting circuits, IEEE Transactions on Applied Superconductivity, [online], https://doi.org/10.1109/TASC.2012.2202116 (Accessed October 18, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact [email protected].

Created October 1, 2012, Updated November 10, 2018
Was this page helpful?