JPS61274422A - Current injection type logical gate circuit using josephson effect - Google Patents

Abstract

PURPOSE:To execute the titled circuit by a wide gate current margin by connecting in series two pieces of resistances, respectively, between plural pieces of pre-stage logical gate circuits and next stage logical gate circuits, and connecting a Josephson junction between the respective connecting points and a ground. CONSTITUTION:Current injection type gate circuits 30, 31 and 32 consist of the same circuit structure as a logical gate circuit shown by an equivalent circuit (figure a). Between connecting points 37, 38 of a resistance and a ground, Josephson 35, 36 are connected. When a current inputted from the connecting points 37, 38 is denoted as Iin, and 2I0/3, (r), and R'L denote a critical current value of a junction 10, a resistance value of a resistance 16, and a resistance value of resistances 33, 34, respectively, a critical current value I1 of the junctions 35, 36 is selected so as to satisfy an expression I. When the circuit 30 is switched, an output current Iin flows into the junction 35, but by a condition of the expression I, the junction 35 is switched, the current Iin is injected from a input terminal 19, and the circuit 32 is switched. In the course of this operation, the junction 36 is in a zero voltage state by the condition of the expression I, and no leak current flows into the circuit 31. Accordingly, a gate current value can be raised to a gate current threshold value 2I0 of the time when no input current is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a current injection type logic gate circuit using the Jira Sefson effect.

(Prior art and its problems) Several circuit construction methods have been proposed for current injection logic gate circuits consisting of Josephson junctions and resistors, one example of which is published in Applied, Physics, Letters (
This is a resistance-coupled area Jisefson logic circuit shown in Applied Physics Letters, Vol. 40, No. 8, pp. 741-744.

FIG. 2 shows a circuit diagram of a conventional current injection type logic gate circuit that performs summation logic. The logic gates each have a critical current value of 2m. /3. Engineering. ,■. Three junctions with 10.
11. 12. Four resistors 13~ with the same resistance value r
16, the logic gate circuit is supplied with a gate current from a power supply current supply terminal 17, and is connected to a resistor 1.
3.15 equal parts g
◇In this state, when the input current is injected into the input terminal 19n, the junctions 11 and 12 change from a zero voltage state to a high resistance state in this order. The gate current I mainly flows through the junction IQ and the resistor 16 to ground.

At this time, when the current flowing through the junction 10 exceeds the critical current value 2I/3, the junction 10 switches to a high resistance state, the gate current flows out to the output terminal 20, and the input current Ii
n flows from the input terminal to ground through the resistor 16, thereby completing input/output separation and completing switching of the gate circuit. It can be seen that during the switching operation of the gate circuit (according to the above explanation), a current of a maximum value of tn+2Io/3 flows through the input resistor 16 immediately before the junction 10 switches.

Figure 3 shows the sum logic gate circuit in Figure 2 as a fan-in 2
．． In the figure, 21, 22, and 23 indicate the logic gate circuits connected in a fan-out 2 configuration, and 17,
19 and 20 respectively represent a power supply current supply terminal, an input terminal, and an output terminal as in FIG. Gate 21 and gate 22 are connected to line 24. Load resistance 25. The gates 23 and 22 are connected through a line 26 and a load resistor 27, respectively. Gate 21 is the input current. When switched to the stain pressure state by applying , the gate current is divided into nine equal parts as the output current, one of which is connected to the line 24. The signal flows through the resistor 25 and is input to the gate 22. As a result, the gate 22 switches to a voltage state, while the gate 23 is in a zero voltage state and the resistor 27 is connected to the input terminal 19 of the gate circuit 22 and to ground through the Josephson junction 12 of the gate circuit 23. This means that it has been done. Therefore, the currents I, , +2I flowing through the input resistor 16 during the switching operation described in the operation of the gate circuit in FIG. /3=Ig/2+2I. /3 is shunted and flows into the input resistor 16 and the load resistor 27 in a magnitude according to their resistance ratio. In a typical design, the input resistance is 1
Ratio r/rL of resistance value r of 6 and resistance value rL of load resistor 27
is about 1/1O, so during the switching operation of the gate 22, the dicarbonate Sefson junction 12K(Ig/2+2I./3)/10 of the gate 23 passes through the line 26 and passes through the line 26 to the gate 23.
A leakage current of the magnitude will flow. Since a current of magnitude /2 is already flowing through the junction 12 due to the application of the gate current Ig, in order for the dielectric junction 12 not to switch due to the leakage current, (I, /2+2I) is required. /3)/10<Io-Ig/2 It is necessary to set the gate current to Ig(1,716)0 If the gate current Ig is set to 1.7I0 or more, the leakage current When the junction 12 of the gate circuit 23 switches to a voltage state and the gate current flows concentratedly to the junction 11 of the gate 23, the junction 11 turns on.Subsequently, the gate current I
g flows concentratedly in the junction 10 of the gate 23, the junction IO is also switched to a voltage state, and the gate current Ig flows to the lines 26, 28 as the output current of the gate circuit 23. This corresponds to the fact that the gate 23 outputs an output current even though no input current is applied, and the gate circuit malfunctions. This leakage current causes the gate circuit to malfunction. If not, the gate current of the gate circuit is 2I'! Normal operation is maintained even when increased.

Therefore, the malfunction due to the leakage current described above significantly limits the operating margin of the gate. To prevent this, the ratio between the load resistance value r1 and the input resistance r should be increased. , in order to obtain a sufficient gate output current, the product of the load resistance value r1 and the gate current must be set to a gap voltage of 7g or less, which is an amount specific to the superelectric material, and the input resistance r must be set to 7g or less. You can also lower it by 1
References Institute of Electronics and Communication Engineers Electronic Devices Study Group Materials ED83-5
As stated in No. 1, page 39, increasing the switching time of the gate significantly impairs the high-speed switching characteristics of the gate circuit using the G-Sefson effect.

(Objective of the Invention) An object of the present invention is to provide a current injection type logic gate circuit using a novel dielectric effect that eliminates the narrow gate current margin characteristic of conventional logic gate circuits.

(Structure of the Invention) According to the present invention, in a current injection type logic gate circuit using the Jime Sefson effect, in which the output terminals of a plurality of pre-stage logic gate circuits and the input terminals of a next-stage logic gate circuit are connected, A first resistor is connected to the output terminal, a second resistor is connected to the other end of the first resistor, another end of the second resistor is connected to the input terminal, and the first resistor is connected to the input terminal. resistance and the second
A current injection type logic gate circuit using the Josephson junction is obtained, characterized in that the Josephson junction is connected between the connection point of the resistor and the ground.

(Detailed Description of Configuration, Examples) The present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a current injection amount logic gate circuit using a Josephson junction, which is an example of a home base. In this embodiment, a logic gate circuit with a fan-in of 2 is assumed. Three current injection gate circuits 30 shown in the figure,
It is assumed that each of 31 and 32 has the same circuit structure as the logic gate circuit shown as an equivalent circuit in FIG. 2, for example.

A second resistor 33.34 is connected to the input terminal 19 of the logic gate circuit 32;
Josephson junction 35.3 with one end of each grounded.
6 is connected to the connection point 37.38, and the previous stage gate circuit 30.31 is connected to the connection point 37.38 via the first resistance 39.40.
output terminal is connected.

Here, if the magnitude of the input current input from each of the connection points 37 and 38 is , then the critical current value of the junction 35 and 36 is selected to satisfy . Here, 2I/3 is the critical current value of junction 10,
r is the resistance value of the resistor 16, and RL is the resistance value of the resistor 33.34. When either of the preceding gate circuits 30, 31, for example 30, switches to a voltage state, the output current flows into the junction 35. According to the above conditional expression, the magnitude of the output current I at this time is larger than the critical current value 11 of the junction 35, so the junction 35 is switched and the output current of the previous gate circuit 30 is injected from the input terminal 19. and the gate circuit 32
switching occurs. During this switching operation, the sum of the maximum currents flowing through the resistor 16 and the resistor 34 is the second
In the conventional gate shown, no current flows through resistor 34 into junction 36, so junction 36 remains at a zero voltage state. Therefore, no leakage current flows into the gate circuit 31 connected from the connection point 38 through the resistor 40.
Malfunction switching of the gate circuit 31 does not occur. Using the gate circuit of this embodiment, a network of logic gate circuits as shown in FIG. 1 can be constructed. Using a typical gate current setting value I = 1.5I, which takes operational margin into account, the bending is g.

It can be seen that the critical current value of junctions 35 and 36 should be selected.

(Effects of the Invention) As described above, if a current injection type logic gate circuit using a Josephson junction according to the present invention is used, the leakage current generated when a plurality of gate circuits is switched is the input terminal of the gate circuit. Since the leakage current is absorbed by the Josephson junction connected to the gate via a resistor, no leakage current is injected from the output side into the gate circuit in the zero voltage state in the previous stage connected to the four inputs of the gate circuit. The gate current value I of the gate circuit can be increased to the gate current threshold value m (2 I in the above embodiment) of the gate circuit when no input current is applied, and the gate current value I of the gate circuit can be increased to a value of 2 I. If you operate it in the margin, you can do it. Furthermore, in the present invention, this objective can be achieved without lowering the input resistance value, so there is no need to increase the delay time of the gate circuit.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram for explaining a network constructed from a current injection type logic gate circuit using the Josephson junction of the present invention, and Fig. 2 is a circuit diagram for explaining a conventional example of a current injection type logic gate circuit. The circuit diagram shown in FIG. 3 is a circuit diagram for explaining a network constructed from conventional current injection type logic gate circuits. 10, 11. 12...Ji1sen/junction, 13°14.15.16...Resistor, 17...Power supply current supply terminal, 18...Grounding, 19...Input terminal, 20...
- Output terminal, 21, 22. 23... Current injection type logic gate circuit, 24, 26, 28... Output line, 25. 2
7...Load resistance, 30. 31. 32... Current injection shop logic gate circuit, 33, 34, 39, 40...
Resistance, 35° 36... Jisen 7son junction, 37.38
・・・Connection point 0 Shrine Jinben 7 Shinai IK Shin 2nd Figure 3

Claims (1)

[Claims] In a current injection logic gate circuit using the Josephson effect, in which the output terminal of each of a plurality of pre-stage logic gate circuits is connected to the input terminal of the next-stage logic gate circuit,
A first resistor is connected to the output terminal, a second resistor is connected to the other end of the first resistor, another end of the second resistor is connected to the input terminal, and the first resistor is connected to the input terminal. A current injection type logic gate circuit using the Josephson effect, characterized in that a Josephson junction is connected between the connection point of the resistor and the second resistor and ground.