Conductus, Inc.

Brian H Moeckly

Yongming Zhang

Chien-Fu Shih

Theodore H Geballe

Kookrin Char

An apparatus for providing dynamic and remote tuning of a cryo-cooled bandpass filter is disclosed. The device includes resonator element and a voltage sensitive element as part of the capacitance in a narrow band filter circuit. A varactor such as a GaAs varactor may be used. Alternatively, a capacitor having a voltage-sensitive dielectric such as SrTiOmay be used. A computer may be connected to the varactor to provide for automated tuning. The voltage-sensitive capacitor may be integral with the resonator element. The invention provides for remote and dynamic tuning of a narrow bandpass filter while located within its sealed cryo-cooled environment.

Varactor tuning for a narrow band filter having shunt capacitors with different capacitance values

A method and apparatus for providing dynamic and remote tuning of a cryo-cooled bandpass filter is disclosed. The device includes resonator element and a voltage sensitive element as part of the capacitance in a narrow band filter circuit. A varactor such as a GaAs varactor may be used. Alternatively, a capacitor having a voltage-sensitive dielectric such as SrTiOmay be used. A computer may be connected to the varactor to provide for automated tuning. The voltage-sensitive capacitor may be integral with the resonator element. The invention provides for remote and dynamic tuning of a narrow bandpass filter while located within its sealed cryo-cooled environment.

Varactor tuning for a narrow band filter including an automatically controlled tuning system

Varactor tuning for a narrow band filter

A conductor suitable for use in oxide-based electronic devices and circuits is disclosed. Metallic oxides having the general composition AMO.sub.3, where A is a rare or alkaline earth or an alloy of rare or alkaline earth elements, and M is a transition metal, exhibit metallic behavior and are compatible with high temperature ceramic processing. Other useful metallic oxides have compositions (A.sub.1-x A'.sub.x)A'.sub.2 (M.sub.1-y M'.sub.y).sub.3 O.sub.7-.delta. or (A.sub.1-x A'.sub.x).sub.m (M.sub.1-y M'.sub.y).sub.n O.sub.2m+n, where 0.ltoreq.x, y.ltoreq.1 and 0.5.ltoreq.m, n.ltoreq.3, A and A' are rare or alkaline earths, or alloys of rare or alkaline earths, A' and A' are alkaline earth elements, alloys of alkaline earth elements, rare earth elements, alloys of rare earth elements, or alloys of alkaline earth and rare earth elements, and M and M' are transition metal elements or alloys of transition metal elements. The metallic oxides grow epitaxially on oxide superconductors as well as on substrates and buffer layers commonly used for growth of oxide superconductors. The oxide superconductors can also be grown epitaxially on these metallic oxides. Vastly improved performance of superconductor-normal-superconductor (SNS) junctions in high temperature superconductor materials are obtained when the normal material is a metallic oxide of the type disclosed. In the preferred embodiment, the conducting oxide CaRuO.sub.3 is used as the normal material in an SNS junelion with YBa.sub.2 Cu.sub.3 O.sub.7-.delta. as superconductor. A dc superconducting quantum interference device (SQUID) functioning at 77K fabricated with this type of junction exhibits large modulation and low noise.

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Palo Alto, CA, United States of America

Brian H Moeckly