A differential circuit board includes a dielectric layer having a first and a second surface, a first conductor line with a first line-width, a second conductor line with a second line-width less than the first line-width, and a ground conductor. The dielectric layer has a first portion with a first thickness between the first and second surface and a second portion with a second thickness less than the first thickness between the first and second surfaces. The first conductor line is disposed on the first surface of the first portion. The second conductor line is disposed on the first surface of the second portion. The ground conductor is disposed on the second surface of the first portion and the second surface of the second portion, wherein the ground conductor overlaps with the first conductor line and the second conductor line. The first and second conductor lines are differential transmission lines.

Techniques for designing and fabricating quantum circuitry, including a coplanar waveguide (CPW), for quantum applications are presented. With regard to a CPW, a central conductor and two return conductor lines can be formed on a dielectric substrate, with one return conductor line on each side of the central conductor and separated from it by a space. The central conductor can have bridge portions that can be raised a desired distance above the substrate and base conductor portions situated between the bridge portions and in contact with the surface of the substrate; and/or portions of the substrate underneath the bridge portions of the central conductor can be removed such that the bridge portions, whether raised or unraised, can be the desired distance above the surface of the remaining substrate, and the base conductor portions can be in contact with other portions of the surface of the substrate that were not removed.

A method may include receiving a first and a second complementary signal to provide differential signaling. The method may further include providing a first conductor trace to transport the first complementary signal; providing a second conductor trace to transport the second complementary signal, the second conductor trace immediately adjacent to the first conductor trace; providing a third conductor trace to transport the first complementary signal, the third conductor trace immediately adjacent to the second conductor trace; and providing a fourth conductor trace to transport the second complementary signal, the fourth conductor trace immediately adjacent to the third conductor trace.

In photonic integrated circuits implemented in silicon-on-insulator substrates, nonconductive channels formed, in accordance with various embodiments, in the silicon device layer and/or the silicon handle of the substrate in regions underneath radio-frequency transmission lines of photonic devices can provide breaks in parasitic conductive layers of the substrate, thereby reducing radio-frequency substrate losses.

Embodiments of this application provide a balance-unbalance conversion apparatus. The apparatus includes an insulation substrate, a first microstrip, a second microstrip, and a conductive ground. The first microstrip includes a first balance signal connection section, a first impedance matching section, and an unbalance signal connecting section. The unbalance signal connecting section is configured to transmit an unbalance signal. The second microstrip includes a second balance signal connecting section, a second impedance matching section, and a ground section. The second balance signal connecting section is configured to transmit a second component of the balance signal. The ground section is configured to connect to a ground signal. The first microstrip, the second microstrip, and the conductive ground are all disposed on the insulation substrate, and a cross-sectional area of at least a part of the first microstrip and/or at least a part of the second microstrip is gradient.

An apparatus includes a signal splitter configured to receive an input signal for transmission and to split the input signal to form two or more sub-signals. The apparatus further includes a first amplifier configured to generate a first amplified sub-signal, a second amplifier configured to generate a second amplified sub-signal, a first launcher coupled to the first amplifier and to a waveguide, and a second launcher coupled to the second amplifier and to the waveguide. The first and second launchers are coupled to the waveguide such that a first radiative signal generated by the first launcher responsive to the first amplified sub-signal and a second radiative signal generated by the second launcher responsive to the second amplified sub-signal are combined in the waveguide to form a transmission signal corresponding to the input signal.

A signal transmission circuit includes a printed circuit board including a surface layer including a signal transmission path that transmits a signal, a signal line through hole that connects the signal transmission path with a signal layer arranged in an inner layer of the printed circuit board, a ground layer of the inner layer of the printed circuit board that forms a return current transmission path for the signal transmission path, and a ground through hole that is connected to the ground layer adjacent to the signal line through hole. A ground pattern including ground areas disposed with a certain distance therebetween and a side ground area connected with at least one end side of the ground areas is disposed at positions of both sides of the signal transmission path. The ground through hole is disposed to connect the ground pattern with the ground layer.

A system includes a first quantum circuit plane that includes a first qubit, a second qubit and a third qubit. A coupled-line bus is coupled between the first qubit and the second qubit. A second circuit plane is connected to the first quantum circuit plane, comprising a control line coupled to the third qubit. The control line and the coupled-line bus are on different planes and crossing over each other, and configured to mitigate cross-talk caused by the crossing during signal transmission.

A multilayer board includes a laminated insulating body, signal conductors inside the laminated insulating body and extending in a transmission direction, and ground conductors sandwiching each of the signal conductors in a lamination direction via the insulating base material layers. The multilayer board includes a parallel extending portion in which the signal conductors extend parallel and that includes signal conductors arranged separately from each other in a direction orthogonal to the transmission direction in a planar view in the lamination direction, and a signal conductor overlapping with the signal conductor in a planar view in the lamination direction and arranged separately from the signal conductor in the lamination direction. The parallel extending portion includes first and second regions arranged separately in a direction orthogonal to the transmission direction in a planar view in the lamination direction.

A multilayer substrate includes an insulator that includes a first region and a second region that is thinner than the first region, and a first signal line and a second signal line that are structured to extend across the first region and the second region. In a region in which the first signal line and the second signal line face each other, a line width of the first signal line and a line width of the second signal line are smaller in the second region than in the first region, and a distance between the first signal line and the second signal line is smaller in the second region than in the first region.