A large winding-ratio planar transformer with an optimized geometry for SQUID ammeter

Juho Luomahaara (Corresponding Author), Mikko Kiviranta, Juha Hassel

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8 Citations (Scopus)


We present a new multiturn gradiometric transformer design. The transformer has a winding ratio of 1284:2 and is composed of a coplanar primary and secondary to overcome the problem of parasitic resonances typically related to planar input circuits with large winding ratios. When applied with a superconducting quantum interference device (SQUID), a highly sensitive current detector down to 25 fA Hz−1/2 is demonstrated. The device characterization yields a coupling coefficient of 0.39 for the transformer.
Original languageEnglish
Article number035006
Number of pages4
JournalSuperconductor Science and Technology
Issue number3
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed


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