Conductus, Inc.

Chien-Fu Shih

Yongming Zhang

Brian H Moeckly

Dawei Zhang

Guo-Chun Liang

Ji-Fuh Liang

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

The present invention provides for a method and apparatus to control non-adjacent cross-coupling in a micro-strip filter. In instances of weak cross-coupling, such as a filter circuit on a high dielectric constant substrate material (e.g., LaAIO with dielectric constant of 24), a closed loop is used to inductively enhance the cross-coupling. The closed loop increases the transmission zero levels. For strong cross-coupling cases, such as a filter circuit on a lower dielectric constant substrate material (e.g., MgO with dielectric constant of 9.6), a capacitive cross-coupling cancellation mechanism is introduced to reduce the cross-coupling. In the latter instance, the transmission zero levels are moved down.

Microstrip filter cross-coupling control apparatus and method

The present invention provides for a super-narrow band filter using frequency dependent L-C components. The invention utilizes a frequency dependent L-C circuit with a positive slope k for the inductor values as a function of frequency. The positive k value allows the realization of a very narrow-band filter.

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Sunnyvale, CA, United States of America

Chien-Fu Shih