JP2968385B2 - AC power supply circuit to Josephson element and circuit board for mounting Josephson element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit and a circuit board, and more particularly to an AC power supply circuit for a Josephson element and a circuit board for mounting the Josephson element using the AC power supply circuit.

[0002]

2. Description of the Related Art A Josephson element which operates at a high speed in a superconducting state at an extremely low temperature is provided in a container filled with liquid helium or the like. An AC power supply circuit is connected between the Josephson element and an AC power supply provided outside the container. Although the power consumption per gate in the Josephson device is small, a large amount of power is required for the entire device because there are many gates in the Josephson device. Therefore, if the diameter of the cable outside the container is increased in order to supply a large current, problems such as an increase in heat absorption or difficulty in keeping the container airtight at the joint with the cable occur. Are set to reduce the diameter, increase the voltage, and reduce the current. On the other hand, in the container, the Josephson element requires a large current. Therefore, it is necessary to amplify the current in the AC power supply circuit.

In an AC power supply circuit for a Josephson element described in Japanese Patent Publication No. 2-30208, current is amplified by a resonance circuit including an inductance formed of a superconducting thin film and a capacitor having a superconductor electrode. .

[0004]

In the conventional AC power supply circuit, it is necessary to form the supply circuit with a superconductor. Therefore, when forming a power supply circuit on a circuit board for mounting a Josephson element made of an insulating substrate, it is necessary to form the power supply circuit on the insulating substrate using thin film technology, and the AC power supply circuit is large on the upper surface of the substrate. Takes up area. As a result, the circuit board for mounting the Josephson element becomes large. Further, the AC power supply circuit formed by the superconductor has a complicated structure, and is difficult to manufacture.

An object of the present invention is to facilitate the manufacture of an AC power supply circuit for a Josephson element and to reduce the size of a circuit board for mounting the Josephson element.

[0006]

An AC power supply circuit for a Josephson element according to the first invention is a power supply circuit for supplying an AC power from a power supply to the Josephson element. This circuit includes a plurality of impedance conversion circuits formed of a resonance line having a length of a quarter of the wavelength of the power supply current and connected in a tree shape from the AC power supply toward the power supply input terminal of the Josephson element. .

According to a second aspect of the present invention, there is provided a circuit board for mounting a Josephson element, wherein an insulating base having a mounting portion for the Josephson element is provided, and AC power from an AC power source is provided to the Josephson element. And a power supply circuit. The power supply circuit is constituted by a plurality of impedance conversion circuits connected in a tree shape from the AC power supply toward the power supply input terminal of the Josephson element and formed of a resonance line having a length of a quarter of the wavelength of the power supply current. ing.

[0008]

In the AC power supply circuit according to the first and second aspects of the present invention, the current is amplified by the plurality of impedance conversion circuits connected in a tree shape, and the amplified current is supplied to the power input terminal of the Josephson element. You. Since this impedance conversion circuit has a simple configuration combining resonance lines, it is easy to manufacture. Further, when this power supply circuit is formed on a Josephson element mounting circuit board made of an insulating substrate, it is not necessary to form the circuit with a superconducting material, and the circuit can be formed in the substrate. Therefore,
The circuit board can be downsized.

[0009]

FIG. 1 shows an AC power supply circuit 1 according to one embodiment of the present invention. The AC power supply circuit 1 has an input side connected to the external AC power supply 4 and an output side connected to a plurality of power supply input terminals 13a of a Josephson element 13 described later.
It is connected to the. External AC power source 4, for example, by supplying an alternating current of 1GH _Z via a coaxial cable, internal impedance (internal resistance 5) is 50 [Omega. On the other hand, the internal impedance of the Josephson element 13 (the internal resistance 13
a) is 6.25Ω. A circuit 1 is provided for impedance matching between the two.

In the AC power supply circuit 1, λ / 4 impedance conversion circuits 6, 7 and 8, each of which has a resonance line having a length of １ of the wavelength of the power supply current, pass from the AC power supply 4 to the Josephson element 13. And are connected in a tree shape. Two first-stage impedance conversion circuits 7 are connected in parallel to the first-stage λ / 4 impedance conversion circuit 6 connected to the AC power supply 4. Further, each second-stage impedance conversion circuit 7 has two third-stage λ / 4
The impedance conversion circuits 8 are connected in parallel, and two Josephson circuits 13 are connected to each third-stage impedance conversion circuit 8. As a result, the first stage λ
The impedance of the / 4 impedance conversion circuit 6 is 25
Ω, the impedance of the second-stage λ / 4 impedance conversion circuit 7 is set to 12.5Ω, and the impedance of the third-stage λ / 4 impedance conversion circuit 8 is set to 6.25Ω.

FIG. 2 shows a specific circuit board 10 for mounting a Josephson element to which an embodiment of the present invention is applied. The circuit board 10 mainly includes an insulating substrate 11 made of mullite ceramic and an insulating layer 12 made of polyimide formed on the insulating substrate 11. A plurality of Josephson elements 13 are fixed on the insulating layer 12 by solder bumps 14.

[0012] Tungsten,
Thick film wiring conductor 1 made of high melting point metal powder such as molybdenum
5 are buried. This thick film wiring conductor 15 includes the AC power supply circuit 1 described with reference to FIG. FIG.
2 shows a part of the pattern of the thick-film wiring conductor 15. In FIG. 3, the input side end 15a of the thick-film wiring conductor 15 has 1
One end of the stage λ / 4 impedance conversion circuit 6 is connected. A second-stage λ / 4 impedance conversion circuit 7 branched from the other end of the first-stage λ / 4 impedance conversion circuit 6,
Reference numeral 7 extends in an S-shape. From the tip of each of the second-stage λ / 4 impedance conversion circuits 7, 7,
Four impedance conversion circuits 8, 8 extend. At the tip of each of the third-stage λ / 4 impedance conversion circuits 8 and 8, a pair of output-side ends 15b to which the power supply terminals of the Josephson element 13 (FIG. 2) are connected are provided.

A thin-film wiring conductor 16 made of copper or niobium is formed inside the insulating layer 12. The thin-film wiring conductor 16 mainly forms a signal wiring, and a portion thereof is connected to the thick-film wiring conductor 15 to supply power to the Josephson element 13. Next, the manufacture of the Josephson element mounting circuit board 10 shown in FIG. 2 will be described.

The insulating substrate 11 is formed from a plurality of ceramic green sheets. The ceramic green sheet is obtained by adding a suitable binder (organic solvent) to a raw material powder such as mullite, silica, calcia, magnesia and the like to form a slurry, which is formed into a sheet by a well-known doctor blade method. After these ceramic green sheets are subjected to appropriate punching, a metal paste composed of a high melting point metal powder such as tungsten or molybdenum is printed and applied by a screen printing method. next,
A ceramic green sheet laminate is formed by laminating a plurality of ceramic green sheets, and about 1 mm in a reducing atmosphere.
By baking at a temperature of 600 ° C., the insulating substrate 11 including the thick-film wiring conductor 15 inside is formed.

The insulating layer 12 is formed by photolithography including a step of applying a photosensitive polyimide paste on the insulating substrate 11 by a spin coating method. The thin-film wiring conductor 16 is formed by applying a physical vapor deposition method such as sputtering or vacuum vapor deposition so as to form a multilayer in the insulating layer 12, and is formed into a predetermined pattern by photolithography. The Josephson element 13 is fixed on the insulating layer 12 via the solder bump 14. With this solder bump 14,
The thin-film wiring conductor 16 and the Josephson element 13 are connected.

In the above manufacturing method, the insulating substrate 11
The internal thick-film wiring conductor 15 is manufactured by a conventionally well-known method of forming a ceramic substrate, and thus is easy to manufacture. In addition, the AC power supply circuit 1 shown in FIG. 3 has a simple configuration in which the impedance conversion circuits 6, 7, and 8 each formed of a resonance line are combined, and therefore, is extremely easy to manufacture. Further, since the AC power supply circuit 1 is formed inside the insulating substrate 11 in the form of the thick-film wiring conductor 15 of FIG.
1, the area occupied by the AC power supply circuit 1 can be reduced, and as a result, the circuit board 1
0 can be reduced in size.

Next, the operation will be described. The power supplied from the external AC power supply 4 is a high voltage and a low current. This current is amplified by the first-stage λ / 4 impedance conversion circuit 6, the second-stage λ / 4 impedance conversion circuit 7, and the third-stage λ / 4 impedance conversion circuit 8 of the AC power supply circuit 1, and is amplified by the Josephson element 13 Supplied to

Here, the impedance (50Ω) of the external AC power supply 4 is set to 25Ω by the first-stage λ / 4 impedance conversion circuit 6, and the second-stage λ / 4 impedance conversion circuit 7
To 12.5Ω and 6.25Ω in the third-stage λ / 4 impedance conversion circuit 8, and the impedance of the Josephson element 13 and the impedance of the supplied power finally match.

Since the signal line composed of the thin-film wiring conductor 16 is arranged separately from the thick-film wiring conductor 15 that is the AC power supply circuit 1, crosstalk to the signal line by the AC power supply circuit 1 is prevented. Is done. Other Embodiments (a) In the above embodiment, the impedance conversion circuits are arranged in a three-stage tree shape, but may be configured in any number of stages. (B) In the above embodiment, the impedance conversion circuit is λ
Although a / 4 line length has been used, an impedance conversion circuit that causes resonance at another line length may be used.

[0020]

In the AC power supply circuits according to the first and second aspects of the present invention, the current is amplified by a plurality of impedance conversion circuits connected in a tree shape, and impedance matching can be achieved. In addition, since the impedance conversion circuit has a simple configuration in which the resonance lines are combined, it is easy to manufacture and the circuit board can be reduced in size.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram of an AC power supply circuit as one embodiment of the present invention.

FIG. 2 is a partially cutaway side view of a circuit board for mounting a Josephson element as one embodiment of the present invention.

FIG. 3 is a partial plan view showing a pattern of the AC power supply circuit of FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 AC power supply circuit 4 External AC power supply 6 First-stage λ / 4 impedance conversion circuit 7 Second-stage λ / 4 impedance conversion circuit 8 Third-stage λ / 4 impedance conversion circuit 10 Circuit board for mounting Josephson element 11 Insulating substrate 12 Insulating layer 13 Josephson element 15 Thick film wiring conductor

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) H01L 39/22 H03K 17/92 H03K 19/195 H01L 39/00 H01L 39/24

Claims (2)

(57) [Claims] 1. A power collector connected from the AC power supply to the tree
A circuit for supplying AC power to a Josephson element, wherein a plurality of impedance conversion circuits each including a resonance line having a length of a quarter of the wavelength of the current are connected to the Josephson element. 2. A plurality of impedance conversion circuits each having a resonance line having a length of a quarter of the wavelength of a power supply current and connected in a tree shape from an AC power supply toward a Josephson element. A circuit board for mounting a Josephson element, wherein the circuit board is configured on an insulating base having a mounting portion.