JPS62115881A - Magnetic field coupling type josephson integrated circuit - Google Patents

Abstract

PURPOSE:To increase the operating margin of a circuit with less variation in magnetic field coupling degree by disposing magnetic field coupling lines of logic elements at the same position for Josephson junction when arranging the different number of magnetic field coupling lines on a Josephson junction of the same size to form different logic elements. CONSTITUTION:In the disposition of magnetic field coupling lines of 2/3 majority gates and 2-input AND gate, lower electrodes 11, 21 are formed of superconducting substance such as lead or niob, and upper electrodes 12, 22 are formed of the same substance. The 2/3 majority gates are the same as the conventional one, but the disposition of the magnetic field coupling line of the AND gate is the same as three of four magnetic field coupling lines of the 2/3 majority gate. With this disposition, the dispositions of the magnetic field coupling line of two types of gate become the same, and the disposition of the magnetic field lines at the center of the upper electrodes having good magnetic field sensitivity can be avoided to reduce the variation in the magnetic field coupling degree. The operating margin of the circuit can be also increased.

Description

[Detailed Description of the Invention] [Summary] Magnetic field coupling degree due to difference in arrangement of magnetic field coupling lines in two or more types of magnetically coupled Josephson gate elements having the same Josephson junction dimensions and different numbers of magnetic field coupling lines. In order to reduce variations in the number of magnetic field coupling lines, a magnetically coupled Josephson integrated circuit is proposed in which gate elements having different numbers of magnetic field coupling lines have the same arrangement of magnetic field coupling lines.

[Industrial application field]

The present invention relates to a magnetically coupled Josephson integrated circuit comprising two or more types of elements having the same Josephson junction dimensions and different numbers of magnetic coupling lines.

Conventionally, when creating logical product or majority decision I- in the same circuit using a Josephson logic element with a large number of magnetic field coupling lines,
Since no particular consideration is given to the arrangement of the magnetic field coupling lines, the degree of magnetic field coupling varies greatly due to differences in the arrangement of the magnetic field coupling lines, and countermeasures are desired.

[Conventional technology]

FIGS. 2(1) and 2(2) are plan views illustrating the arrangement of magnetic field coupling lines of a conventional 2/3 majority gate and a two-input AND gate, respectively.

In the figure, 11.21 is a lower electrode made of a superconducting material such as lead or niobium, 12.22 is an upper electrode made of the same superconducting material, 13.23 is a Josephson junction region, and 14.15.16.17 , and 24.25.26 are magnetic field coupling lines.

The magnetic field coupling line is concentrated at the center of the upper electrode 13.23.
Four /3 majority gates and three 2-input AND gates are provided.

One of the magnetic field coupling lines for both gates is for providing a magnetic field offset.

Offset of the magnetic field is performed by passing a direct current through this magnetic field coupling line and biasing the magnetic field to an appropriate value.

In the arrangement of the magnetic field coupling lines in this example, the degree of magnetic field coupling is different between the 2/3 majority gate and the two-input AND gate, and furthermore, in the AND gate with the magnetic field coupling line in the center, the degree of magnetic field coupling of the central magnetic field coupling line is different. is larger than the other two lines, and there is a disadvantage that the degree of magnetic coupling between the magnetic coupling lines of the same gate increases.In essence, the circuits in Figure 2 +1) and (2) have the same signal level. is input, each circuit does not have the characteristic of responding at the same level, and the operating margin becomes small.

[Problem that the invention seeks to solve]

In conventional magnetically coupled Josephson integrated circuits, which are made up of two or more types of elements with the same Josephson junction dimensions and different numbers of magnetic coupling lines, variations (differences) in the degree of magnetic coupling are large, and the operating margin of the circuit is limited. is small.

[Means for solving problems]

To solve the above problem, when different numbers of magnetic field coupling lines are arranged on Josephson junctions having the same dimensions to form different logic elements, the magnetic field coupling lines of each element are connected to each Josephson junction. This is achieved by a magnetically coupled Josephson integrated circuit according to the present invention, which is arranged in the same position as the magnetic field.

In particular, one magnetic field coupling line for magnetic field offset, three and two magnetic field coupling lines for input signals are arranged on Josephson junctions having the same dimensions, respectively, to form a 2/3 majority gate element and two input signals. When forming an AND element, two magnetic field coupling fibers are arranged symmetrically with respect to the center of each Josephson junction, and one of them is removed. The invention has great effects in integrated circuits.

[Effect]

The present invention provides a magnetically coupled Josephson integrated circuit consisting of two or more types of elements with the same Josephson junction dimensions and different numbers of magnetic coupling lines, by making the arrangement of the magnetic coupling lines the same for each element. It was experimentally confirmed that the difference in magnetic field sensitivity could be reduced, and the result was applied to logic circuits.

In particular, the magnetic field coupling cotton has a high magnetic sensitivity at the center of the joint, so it was arranged to avoid the center.

〔Example〕

FIGS. 1(1) and 1(2) are plan views illustrating the arrangement of magnetic field coupling lines of a 2/3 majority gate and a two-input AND gate, respectively, according to the present invention.

In this embodiment as well, in contrast to the conventional example shown in FIG. 2, the above combination is adopted for the circuit configuration for simplicity.

In the figure, 11.21 is a lower electrode made of a superconducting material such as lead or niobium, 12.22 is an upper electrode made of the same superconducting material, 13.23 is a Josephson junction region, and 14.15.16.17 , and 248, 25A, 2
68 is a magnetic field coupling line.

The 273 majority gate in Figure 1 (1) is the same as the conventional example in Figure 2 (1), but the arrangement of the magnetic field coupling lines of the AND gate in Figure 1 (2) has been changed to the four 273 majority gates. It is made the same as three of the magnetic field coupling wires.

Furthermore, in FIG. 1(2), the lowermost magnetic field coupling line is removed, but any other line may be removed.

By adopting this arrangement, the arrangement of the magnetic field coupling lines of the two types of gates is the same, and it is possible to avoid arranging the magnetic field coupling lines in the center of the upper electrode, where the magnetic field intensity is particularly good. It is possible to reduce variations in the circuit and increase the operating margin of the circuit.

FIG. 3 is a cross-sectional view along the line 8 to explain the structure of the Josephson device.

In the figure, reference numeral 1 denotes a tunnel junction made of a thin alumina layer or the like, which is formed between a lower electrode 21 and an upper electrode 22 each made of a superconducting material to form a Josephson junction.

2 is a thick insulating layer that defines the area 23 of the Josephson element.

The magnetic field coupling lines 24A, 25A, 26A are the upper electrode 22
is formed on top of the insulating layer 3 with an insulating layer 3 interposed therebetween.

Next, a full adder will be described as an example of a circuit configured with the different types of gates explained in the above example.

FIGS. 4(1) and 4(2) are circuit diagrams of a full adder using current flip-flops using Josephson elements.

FIG. 4(1) shows a sum signal generating circuit, and FIG. 4(2) shows a carry signal generating circuit.

As an example of configuring a full adder with a current flip-flop consisting of a superconducting loop, consider the sum signal S.

, carry signal C, , can be realized by the following logic.

Sn = An (B,, Cn-+ "Bn Cn-+
)+An(Bh Cn-11-B,,c,-,>.

Cn = AII Bn + C1N-1 (All + B
n).

So -, = A, , B, ten. -1 (τn + ■n).

Here, All, BI are input signals, and C, , -1 are carry signals from the previous stage.

The sum signal S7 can be constructed from a logical sum and an AND gate according to the above logic.

The carry signal C7 can be realized according to the above logic, but in order to reduce the number of circuit stages, it can be realized with one stage of 2/3 majority gate.

That is, the 2/3 majority gate has input signals A1, B7,
and 2 of the 3 inputs of carry signals C,, -+ from the previous stage
If one or more are "1", the carry signal c7 becomes "1".

In the figure, each loop is a current flip-flop with a Josephson junction in each branch.

The x mark indicates a Josephson junction (referred to as JJ), and the arrow and U-shaped symbol indicate a magnetic field coupling line, to which the above input signal is applied.

In this case, the 2-input AND gate and the 273 majority vote gate are the threshold values of all magnetic field coupling lines [the limit value of the control current (current flowing through the magnetic field coupling lines) that allows superconducting current to flow through the Josephson junction] Since it is desired that the two parts be the same, the structure shown in FIG. 1 according to the present invention was adopted.

〔Effect of the invention〕

As explained in detail above, according to the present invention, in a magnetically coupled Josephson integrated circuit consisting of two or more types of elements having the same Josephson junction dimensions and different numbers of magnetic coupling lines, variations in the degree of magnetic coupling can be achieved. is small, and the circuit operating margin is large.

[Brief explanation of drawings]

Figure 1 (1) and (2) are 2 and '3 according to the present invention, respectively.
A plan view illustrating the arrangement of the magnetic field coupling lines of the majority gate and the two-input AND gate. Figures 2 (1) and (2) are the magnetic field coupling lines of the conventional 2/3 majority gate and the two-input AND gate, respectively. Figure 3 is a cross-sectional view taken along line 8 in Figure 1 to explain the structure of the Josephson element. Figures 4 (1) and (2) show a current free knob flop using the Josephson element. FIG. 3 is a circuit diagram of the full adder used. In the figure, 11.21 is the lower electrode, 12.22 is the upper electrode, 13.23 is the Josephson junction region, 14.15.16.17.24A, 25A, 2
6A is a magnetic field coupling line. Patent applicant: Director of the Agency of Industrial Science and Technology Tatsu Todoroki Conventional f111t
Z-Yoru-kai 1 Hunun 2

Claims (2)

[Claims] (1) When arranging different numbers of magnetic field coupling lines on Josephson junctions having approximately the same dimensions to form different logic elements, the magnetic field coupling lines of each element are connected to each Josephson junction. A magnetically coupled Josephson integrated circuit characterized by being arranged at the same position. (2) One magnetic field offset magnetic field coupling line and two input signal magnetic field coupling lines are arranged on Josephson junctions having approximately the same dimensions to form a 2/3 majority gate element, and 2 When forming the input AND gate element,
The magnetic field coupling according to claim 1, characterized in that two magnetic field coupling lines are provided symmetrically with respect to the center of each Josephson junction, and one of the magnetic coupling lines is arranged except for one. Type Josephson integrated circuit.