JPS59190722A - Josephson logical gate - Google Patents

Abstract

PURPOSE:To obtain a Josephson logical gate which has a large operation margin and small occupation area by applying an input signal current to a dual-junction superconductive quantum interferometer through a magnetic field coupled control line. CONSTITUTION:Inductance L3 and L4 of the magnetic field coupled control line LC and bias current lines Lb1 and Lb2 couple with inductance L1 and L2 of 3:1 through a magnetic field. Then, the input signal current is passed through the magnetic field coupled control line LC and then applied to the dual-junction superconductive quantum interferometer having the superconductive inductances L1 and L2. A figure shows threshold value characteristics when the L.I product of this gate is phi0. Thus, the intersections B and B' of the threshold value characteristic curve and a segment 0A are decrease and the margin becomes about + or -17% wider.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a Josephson logic gate using a two-junction superconducting quantum interferometer having a pair of Josephson junctions and a superconducting inductance.

(b) Prior art and problems Conventionally, as a logic gate with a large operating margin, T, R, Gheewala, IBM, 'J
, Res.

Develop, Vol. 24. No. 2 (1980)
CIL (Curr
ent Injection Logic) 7 Temily is known. If the allowable range of deviation in the manufacturing process from the set value of the critical current value of the Josephson junction is ±20, the operating margin of an OR gate using a three-junction superconducting quantum interferometer in the CIL family is ±26. %
Adashi, CID (Current Injection)
The AND gate using a two-junction superconducting quantum interferometer called ``Device'' has ±17 chi. Other gate families have smaller operating margins. O H-Beha et al.
7, No. 6 (1981) pp. 3423-3425.
Current Injection Device
) has an operating margin of ±33%, but it is an AND gate and not a 90R gate. By the way, the three-junction superconducting quantum interferometer, which is the OR gate of the CIL family, occupies a large area, and in the 25 μm rule, it is 50 Itm
At about 0.00 μm, the area is about five times that of 6D and CID, which limits high integration. Therefore, if the degree of integration is to be further increased, an IOR gate with a large operating margin and a small occupied area is required. Also, S1M, Far
iska ICCC (19, 80) collection of papers pp, 119
The gate described in No. 6-1201 uses the above-mentioned CID as an injection type OR gate, and although the area is small, the operating margin as an OR is small. If an attempt is made to improve this by using a current amplification circuit, the occupied area will increase, leading to an increase in power consumption and a decrease in operating margin.

Below, we will look specifically at conventional Josephson logic gates.

FIG. 1(a) shows an equivalent circuit of a CID, which is one of the two-junction superconducting quantum interferometers, and FIG. 1(b) shows its threshold characteristics when the L/shape is 1.74Φ0.

In Figure 1(a), Jl and J2 have critical current ratios of 1.
:3 Josephson junction, L++ LtH3:
1 noise inductance, and Lb is a bias current line.

In FIG. 1(b), the horizontal axis Ia is the sum of input signal currents, and the vertical axis Ib is the bias current supplied through the bias current line Lb.

Since the input signal current is injected, the fan-outs are parallel, but when the number of fan-outs is 2, as shown in Figure 1 (bl
The bias margin is between the intersection point B of the line segment OA and the threshold characteristic and the threshold point C in the unmanned signal state. In reality, it is necessary to allow a deviation of ±20% in the critical current value due to the manufacturing process, and the bias range is between B' and C', so the operating margin is only ±10 inches.

(C) Object of the Invention An object of the present invention is to provide a Josephson logic gate with a large operating margin and a small occupied area.

(d) Structure of the invention In order to achieve the above object, the present invention has a critical current ratio of l:
A bias current is supplied to a two-junction superconducting quantum interferometer having a pair of Josephson junctions and a superconducting inductance of 3, and a point dividing the conducting inductance of the two-junction superconducting quantum interference needle at a ratio of 3:1. and a control line magnetically coupled to the superconducting inductance, and the input signal current is injected into the two-junction superconducting quantum interferometer after passing through the control line.

(e> Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2(a) is a diagram showing an embodiment of the present invention.

In the figure, L8+L4 indicates the inductance of the magnetic field coupling control line Lc, Lb++Lbz indicates the bias current line, and these have an inductance Le of 3:1.
t Magnetically coupled with Lt. Note that the same reference numerals as in other FIG. 1 indicate the same things.

As is clear from the figure, after the input signal current IB passes through the magnetic field coupling control line Lc, it is connected to the Josephson junction JI, Jt with a critical current ratio of 1=3 and the superconducting inductance Ll, L.
, into a two-junction superconducting quantum interferometer.

The L shape of such a gate is Φ. The threshold value characteristic in the case of is shown in FIG. 2(b). As is clear from this, the intersections B and B' between the threshold characteristic curve and the line segment OA decreased, and the margin widened to ±17%. In FIG. 2(a), the bias current is applied from the bias current line Lb+ or Lbt.

FIG. 3 is a diagram showing a second embodiment of the present invention, in which magnetic field coupling control lines having inductances L, L6 are further provided, and the input signal current is passed through the two control lines, and then the superconducting quantum interferometer is connected to the superconducting quantum interferometer. It is configured to be injected into

In this case, the occupied area increases, but the operating margin becomes larger than in the first embodiment.

FIG. 4 is a diagram showing a third embodiment of the present invention. In this embodiment, resistors rl and rl are provided so that the injection current is □ times the input signal current, and the level of the injection current can be adjusted by changing the rl+r2 value of the resistor rl+r3.

FIG. 5 is a diagram showing a fourth embodiment of the present invention. This embodiment aims to separate input and output, and the Josephson junction for wide isolation is connected to either position Js or J41 Js-Ja, and the isolation resistor is connected to either position rl or r21rs. be done.

FIG. 6 shows that in the fifth embodiment of the present invention, the number of inputs is 4.
Application examples of these Josephson logic gates according to the present invention will be shown below in order to perform a manual OR operation.

The gate shown in Figure 2) is simply indicated by the symbol shown in Figure 7.

Figure 8 shows resistance RT, RstX Jita Sefson junction J.

An example is shown in which a current amplification circuit CA having the following is connected.

When two outputs are taken out in parallel, the operating line on the threshold characteristic is line segment OA' in FIG. 2(b), and the next stage can be driven with a large signal current.

Note that if the number of outputs is 3, the operating line will be the line segment OA'' in Figure 2(b), and the same margin as the number of outputs of 2 without connecting the current amplifier circuit will be obtained. A configuration is shown in which a Joseon junction JIG is connected to an OR gate via resistors RT+ and RTt to perform an AND operation.

FIG. 10 shows a configuration that performs an AND operation similar to the configuration shown in FIG. 9, in which two O
As described in detail of the 0(f) invention in which R gates are connected, according to the present invention, the occupied area is small;
A Josephson logic gate with large operating margin is provided.

[Brief explanation of drawings]

FIG. 1(a) shows a conventional Josephson logic gate, FIG. 1(b) shows its threshold characteristics, and FIG.
a) is a diagram showing the first embodiment of the present invention, FIG. 2 (bl is a diagram showing its threshold characteristic, FIG. 3 is a diagram showing the second embodiment of the present invention, and FIG. 4 is a diagram showing the second embodiment of the present invention. FIG. 5 is a diagram showing a fourth embodiment of the invention, FIG. 6 is a diagram showing a fifth embodiment of the invention, and FIG. 7 is a diagram showing a fifth embodiment of the invention. , a diagram showing symbols indicating the gate of the present invention, and FIGS. 8 to 10 are diagrams each showing an application example of the gate of the present invention. In the figures, J+ and Jx are Jose7 non-junctions, Ll. L2 is superconducting inductance, Lb is bias current line,
Lc indicates a magnetic field coupling control head. Applicant: Director of the Institute of Industrial Science and Technology

Claims (1)

[Claims] A two-junction superconducting quantum interferometer having a pair of Joseph So/junction and superconducting inductance with a critical current ratio of 1:3, and a point where the superconducting inductance of the two-junction superconducting quantum interferometer is divided into 3:1. and a control An for magnetically coupling the superconducting inductance, and the input signal current is injected into the two-junction superconducting quantum interferometer after passing through the seven control lines. Characteristic Jose7/logic gate.