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 May 12, 2026)
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A 4:1 transmission-line impedance transformer for broadband superconducting circuits
Published
Author(s)
, , , 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
Pub Type
Journals
Download Paper
Keywords
Superconducting microwave devices, impedance matching, transformers
Citation
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Created October 1, 2012, Updated November 10, 2018