An electrical filter structure for forwarding an electrical signal from a first port, e.g. P1, to a second port, e.g. P2, in a frequency selective manner, wherein the filter is a microwave filter, the electrical filter structure comprising: a plurality of pairs of an open stub and a short-circuited stub coupled electrically in parallel to a transmission line comprising a plurality of transmission line portions at a plurality of respective junctions between adjacent transmission line portions, e.g. Cross junction; and wherein the first port is connected with a first of the junctions having a first pair comprising a first open stub and a first short-circuited stub; wherein the second port is connected with a last of the junctions having a last pair comprising a last open stub and a last short-circuited stub; wherein lengths of the pair of the open stub and the short-circuited stub coupled to a same of the junctions are chosen such that electrical lengths of the open stub and short-circuited stub of the respective pairs are equal within a tolerance of +/10%.

An electronic circuit includes a band-pass filter, and at least one first circuit. The band-pass filter includes a plurality of filter resonators. Two adjacent filter resonators included in the filter resonators are mutually couplable. The first circuit includes a first qubit and a first readout resonator. The first readout resonator is couplable with the first qubit and one of the filter resonators. A passband of the band-pass filter includes a first passband and a second passband. A magnitude of a first ripple of the first passband is not more than 1/10 of a magnitude of a second ripple of the second passband.

In some aspects, a quantum information processing circuit includes a lumped-element device on the surface of a dielectric substrate. The lumped-element device can include a capacitor pad and an inductive transmission line. The capacitor pad can be capacitively coupled to another capacitor pad. The inductive transmission line can reside in an interior clearance area defined by an inner boundary of the capacitor pad. The lumped-element device can be, for example, a resonator device or a filter device. The inductive transmission line can be, for example, a meander inductor.

A waveguide structure or a printed-circuit board is formed using a plurality of unit structures which are repetitively aligned in a one-dimensional manner or in a two-dimensional manner. The unit structure includes first and second conductive planes which are disposed in parallel with each other, a transmission line having an open end which is formed in a layer different from the first and second conductive planes and positioned to face the second conductive plane, and a conductive via electrically connecting the transmission line to the first conductive plane.

A waveguide structure or a printed-circuit board is formed using a plurality of unit structures which are repetitively aligned in a one-dimensional manner or in a two-dimensional manner. The unit structure includes first and second conductive planes which are disposed in parallel with each other, a transmission line having an open end which is formed in a layer different from the first and second conductive planes and positioned to face the second conductive plane, and a conductive via electrically connecting the transmission line to the first conductive plane.

A flat cable high-frequency filter includes a dielectric substrate extending in a transmission direction of a high-frequency signal. The dielectric substrate includes dielectric layers stacked on each other. Elongated conductor patterns are provided on a flat surface of one dielectric layer which faces another dielectric layer. The conductor patterns are as wide as possible in the dielectric substrate in accordance with a desired inductance. A capacitive coupling conductor pattern opposes one conductor pattern by a predetermined area with a dielectric layer therebetween. By using a connecting conductor, the capacitive coupling conductor pattern is connected to the conductor pattern which does not oppose the capacitive coupling conductor pattern.

The present invention related to self-limiting filters, arrays of such filters, and methods thereof. In particular embodiments, the filters include a metal transition film (e.g., a VO.sub.2 film) capable of undergoing a phase transition that modifies the film's resistivity. Arrays of such filters could allow for band-selective interferer rejection, while permitting transmission of non-interferer signals.

A flat cable high-frequency filter includes a dielectric substrate extending in a transmission direction of a high-frequency signal. The dielectric substrate includes dielectric layers stacked on each other. Elongated conductor patterns are provided on a flat surface of one dielectric layer which faces another dielectric layer. The conductor patterns are as wide as possible in the dielectric substrate in accordance with a desired inductance. A capacitive coupling conductor pattern opposes one conductor pattern by a predetermined area with a dielectric layer therebetween. By using a connecting conductor, the capacitive coupling conductor pattern is connected to the conductor pattern which does not oppose the capacitive coupling conductor pattern.

A coplanar waveguide based (CPW-based) millimeter-wave (mmWave) bandpass filter is disclosed. The filter may comprise a substrate, first and second ground metal plates, an input signal transmission line and an output signal transmission line, and four half-wavelength CPW resonators. A T-slot or an I-slot is optionally embedded into each CPW resonator to improve the suppression at the upper stopband. Optionally, the filter may further comprise two T-stubs respectively connected to the first and second ground metal plates to reduce the size of the filter and generate transmission zeros in the lower stopband. Optionally, the filter may further comprise a cross-shaped dual-mode resonator in a central area of a CPW plane to increase the bandwidth of the filter. The proposed CPW-based mmWave bandpass filter(s) can achieve low passband insertion loss, high out-band suppression, miniature size, and low cost.