JP2775824B2 - Josephson drive circuit with polarity switching - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a superconducting integrated circuit using a Josephson element, and more specifically, to inject current into a word line, a bit line, etc. of a superconducting memory integrated circuit. The present invention relates to a polarity switching type Josephson drive circuit capable of arbitrarily reversing the direction of current.

(Prior Art) FIG. 5 shows an equivalent circuit diagram for describing a conventionally known polarity switching type Josephson drive circuit (Showa 1).
(IEICE Spring National Convention 1988). A conventional technique will be described with reference to FIG.

As shown in FIG. 5, this drive circuit includes four Josephson gate circuits (J ₁ , J ₂ , J ₃ , J ₄ ) and three resistors (R ₁ , R ₂ , R ₄ ).
₃ ) and a driven line composed of a word line or a bit line of a memory cell array. In this circuit, when generating an output current in the driven line clockwise,
The input signal I _in 1 switches the Josephson gate circuits J ₁ and J ₃ to a voltage state, and the gate current I _g 1 flows through the driven line. Gate current I _g 1 flowing to the driven line flows into the ground through the Josephson gate circuit J _4. On the other hand, when an output current is generated in the driven line in the counterclockwise direction, the Josephson gate circuits J ₂ and J ₄ are switched to a voltage state by the input signal I _in 2, and the gate current _Ig 2 is changed to the driven line. Flows to The gate current I _g 2 flowing in the driven line is
It flows into the ground through the Josephson gate circuit J _3.

As described above, it is possible to realize a polarity switching type Josephson drive circuit that can inject a current into a driven line and arbitrarily invert the direction of the current by the conventional technique.

(Problems to be Solved invention) In the conventional art, in order to inject the gate current I _g 1 in the clockwise direction to the driven line by input signal I _in 1 Josephson gate circuit J ₁ voltage switched to a state, after the gate current I _g 1 flows through the Josephson gate circuit J ₃ through the resistor R _1, it is necessary to switch the Josephson gate circuit J ₃ to the voltage state. Similarly, in order to inject the gate current _Ig 2 in the counterclockwise direction into the driven line, the input signal I _in 2 switches the Josephson gate circuit J ₂ to the voltage state, and the gate current _Ig 2 after flowing in the Josephson gate circuit J ₃ through the resistor R _2, it is necessary to Josephson gate circuit J ₄ is switched to the voltage state.

Thus, in order for this drive circuit to operate, the Josephson gate circuit J ₁ , J ₃ or J ₂ , J ₄ needs to be switched twice in sequence, which is a problem in operating the circuit at high speed. There was a point. Furthermore, in the prior art, since the magnetic coupling type interferometer gate is used as the Josephson gate and the circuit, there is a problem that the gate area becomes large and miniaturization is difficult.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such a problem of the conventional polarity switching type Josephson driving circuit and to provide a polarity switching Josephson driving circuit capable of miniaturizing the circuit and operating at high speed.

(Means for Solving the Problems) According to the present invention, a first bias resistor connected between a bias supply terminal and a first terminal and a first bias resistor connected between the first terminal and the second terminal are provided. A first Josephson element; a second Josephson element connected between the second terminal and ground; a first load resistor connected between the first terminal and ground; A first input resistor connected between the first input terminal and the first input terminal; a second input resistor connected between the first terminal and the second input terminal; A second bias resistor connected between the third terminal, a third Josephson element connected between the third terminal and the fourth terminal, and a second bias resistor connected between the fourth terminal and the ground. A fourth load resistor connected between the third terminal and ground; A third input resistor connected between a terminal and the second input terminal; a fourth input resistor connected between the third terminal and the first input terminal; A first polarity switching type Josephson drive circuit, comprising: a driven line connected between fourth terminals; and a third load resistor inserted into the driven line. In the first polarity switching type Josephson drive circuit, a fifth Josephson element inserted between the first terminal and the second input resistor, the second input resistor and the fifth Josephson A first input / output isolation resistor having one end connected between elements and the other end grounded; a sixth Josephson element inserted between the second terminal and the first input resistance; One end is connected between the input resistor and the sixth Josephson element, and the other end is grounded. A second input / output isolation resistor, a seventh Josephson element inserted between the third terminal and the fourth input resistance, and a fourth Josephson element between the fourth input resistance and the seventh Josephson element. A third input / output isolation resistor having one end connected and the other end grounded, an eighth Josephson element inserted between the fourth terminal and the third input resistor, and a third input resistor. A second polarity switching type Josephson drive circuit, comprising: a fourth input / output isolation resistor having one end connected between the eighth Josephson element and the other end grounded. And in the second polarity switching type Josephson drive circuit, a series connection is made instead of the second Josephson element, the fourth Josephson element, the sixth Josephson element, and the eighth Josephson element. Multiple Josephson devices A third polarity switching type Josephson driving circuit characterized by comprising been obtained.

(Embodiment) FIG. 1 is an equivalent circuit diagram for explaining an embodiment of the first aspect of the present invention.

The first embodiment uses a Josephson device (J ₁ , J ₂ , J ₃ , J ₄ )
And bias resistors (R _B1 , R _B2 ) and input resistors (R _I1 , R _I2 , R _I3 , R
_I4) and the load resistor _{(R L1, R L2, R} L3) and composed of a driven line made of a memory cell array.

The operating principle of the polarity switching type Josephson drive circuit of the first embodiment is as follows.

Bias current from bias supply terminal B is bias resistance
Through R _B1 Josephson device J ₁ and J _2, bias resistor R
In a state of being supplied to the Josephson device J ₃ and J ₄ through _B2, the input signal is inputted from the input terminal I _n1 is Josephson device J ₂ and J ₃ is switched to the voltage state, flows through the bias resistor R _B1 Most of the bias current flowed into the driven line including the memory cell array. On the other hand, most of the bias current flowing through the bias resistor _RB2 flows to the ground through the load resistor _RL2 . Therefore, even flow into the Josephson device J ₄ through a bias current load resistor R _L3 that has flowed to the driven line, Josephson device J ₄
Already not switch voltage state for a state of not being biased, current flows into the Josephson device J ₄ flows to the ground. By the above operation, the driving current can be injected in the clockwise direction into the driven line including the memory cell. Similarly, it is possible when the input signal is inputted from the input terminal I _n2 Josephson device J ₁ and J ₄ are switched to the voltage state, to inject a driving current to the driven line in a counterclockwise direction.

Here, if the superconducting critical current values of the Josephson junctions J ₁ , J ₂ , J ₃ , and J ₄ are I ₁ , I ₂ , I ₃ , and I ₄ , the following conditions must be satisfied.

I ₁ = I ₃ , I ₂ = I ₄ , I ₁ ≧ I _{2 As} described above, the circuit of the present embodiment is a circuit in which the Josephson elements J ₂ and J ₃ or J ₁ and J ₄ are simultaneously switched once. , High-speed operation is possible. Further, since the function of the gate formed of the magnetic coupling type interferometer used in the conventional technique is performed by one Josephson element, the circuit can be miniaturized.

FIG. 2 is an equivalent circuit diagram for explaining an embodiment of the present invention.

In the second embodiment, the Josephson devices (J ₁ , J ₂ , J ₃ , J ₄ ,
J ₅ , J ₆ , J ₇ , J ₈ ), bias resistors (R _B1 , R _B2 ), input resistors (R _I1 , R _I2 , R _I3 , R _I4 ), and load resistors (R _L1 , R _L2 , R _L3) ), Input / output isolation resistors (R _d1 , R _d2 , R _d3 , R _d4 ) and a driven line composed of a memory cell array.

The operating principle of the polarity switching type Josephson drive circuit of the second embodiment is as follows.

Bias current from bias supply terminal B is bias resistance
Through R _B1 Josephson device J ₁ and J _2, bias resistor R
In a state of being supplied to the Josephson device J ₃ and J ₄ through _B2, the input signal is inputted from the input terminal I _n1 Josephson device J ₂ and J ₃ and J ₅ and J ₆ and J ₇ is a voltage state Switch and
Most of the bias current flowing through the bias resistor _RB1 flows into the driven line including the memory cell array.
On the other hand, most of the bias current flowing through the bias resistor _RB2 flows to the ground through the load resistor _RL2 . Therefore, the bias current flowing into the driven line becomes the load resistance R
Also flows into the Josephson device J ₄ through _L3, without switching to voltage state for Josephson device J ₄ is already state of not being biased, current flows into the Josephson device J ₄ flows to the ground. On the other hand, the input signal input from the input terminal I _n1, after Josephson device J ₆ and J ₇ is switched to the voltage state, flows to the ground through the output isolation resistor R _d1 and R _d4, respectively. Therefore, the input signal can be completely separated from the output signal.

By the above operation, in the state where the input and output are separated,
A driving current can be injected in a clockwise direction into a driven line including a memory cell. Similarly, when the input signal is inputted from the input terminal I _n2 Josephson device J ₁ and J ₄ and J ₅
J ₇ and J ₈ is switched to the voltage state, it can be injected drive current to a driven line in the counterclockwise direction in a state where the input and output separation was worn.

Here, similarly to the first embodiment, Josephson junctions J ₁ , J
_{If the} superconducting critical current values of ₂ , J ₃ and J ₄ are I ₁ , I ₂ , I ₃ and I ₄ , the following conditions must be satisfied.

I ₁ = I ₃ , I ₂ = I ₄ , I ₁ ≧ I _{2 As} described above, the second embodiment has the same effect as the first embodiment, and has an input / output separation function. A polarity switching type Josephson drive circuit can be realized.

FIG. 3 is an equivalent circuit diagram for explaining an embodiment of the third aspect of the present invention.

In the third embodiment, Josephson devices (J ₁ , J ₂₁ , J ₂₂ , J ₃ ,
J ₄₁ , J ₄₂ ), bias resistors (R _B1 , R _B2 ), and input resistors (R _I1 ,
R _I2 , R _I3 , R _I4 ), load resistors (R _L1 , R _L2 , R _L3 ) and a driven line composed of a memory cell array.

The third embodiment, in the first embodiment, same as the circuit obtained by replacing the Josephson device J ₂ and Josephson devices J ₂₁ and J ₂₂ and J ₄₁ and J ₄₂ to J ₄ a are respectively connected two series It is. The operating principle of the circuit is the same as in the first embodiment. The operating time of the circuit can be evaluated by Li / V, where L is the inductance of the driven line composed of the memory cell array, V is the driving voltage, and i is the driving current (output current). The drive voltage V is determined by a voltage generated when the Josephson element switches to a voltage state. Therefore, in this embodiment, by connecting two Josephson elements in series, a drive voltage twice as large as that of the first embodiment is generated, and the operation time can be shortened.

In this embodiment, two Josephson elements are connected in series. However, by using three or more Josephson elements connected in series, the driving voltage can be further increased and high-speed operation can be performed.

As described above, according to the third embodiment, it is possible to realize a polarity switching type Josephson drive circuit having the same effects as the first embodiment and capable of operating at a higher speed.

FIG. 4 is an equivalent circuit diagram for explaining an embodiment of the third aspect of the present invention.

In the fourth embodiment, a Josephson device (J ₁ , J ₂₁ , J ₂₂ , J ₃ ,
J ₄₁ , J ₄₂ , J ₅ , J ₆₁ , J ₆₂ , J ₇ , J ₈₁ , J ₈₂ ), bias resistors (R _B1 , R _B2 ), and input resistors (R _I1 , R _I2 , R _I3 , R _I4 ) And load resistances (R _L1 , R _L2 , R _L3 ), input isolation resistances (R _d1 , R _d2 , R _d3 , R _d4 ), and a driven line composed of a memory cell array.

The fourth embodiment is different from the second embodiment in that Josephson elements (J ₂₁ , J ₂₂ ) in which _two Josephson elements J ₂ and J ₄ , J ₆ and J ₈ are respectively connected in series, and (J ₄₁ And _J42 ) and ( _J61 , J
₆₂ ) and ( _J81 and _J82 ). The operation principle of the circuit is the same as in the second embodiment.

In the present embodiment, by connecting two Josephson elements in series, a drive voltage twice as large as that of the second embodiment is generated, and the operating time is increased for the reason described in the section of the third embodiment. Can be shortened.

In this embodiment, as in the third embodiment, two Josephson elements are connected in series. However, by using three or more Josephson elements connected in series, the drive voltage can be further increased to achieve high-speed operation. Becomes

As described above, according to the fourth embodiment, it is possible to realize a polarity switching type Josephson drive circuit having the same effects as the second embodiment and capable of operating at a higher speed.

(Effect of the Invention) As described above, according to the present invention, it is possible to realize a polarity switching type Josephson drive circuit capable of miniaturizing a circuit and operating at high speed.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram for explaining an embodiment of the polarity switching type Josephson drive circuit according to the first aspect of the present invention. FIG. 2 is an equivalent circuit diagram for explaining an embodiment of the polarity switching type Josephson drive circuit according to the second aspect of the present invention. FIG. 3 is an equivalent circuit diagram for explaining an embodiment of the polarity switching type Josephson drive circuit according to the third aspect of the present invention. FIG. 4 is an equivalent circuit diagram for explaining an embodiment of the polarity switching type Josephson drive circuit according to the third aspect of the present invention. FIG. 5 is an equivalent circuit diagram for explaining a conventional polarity switching type Josephson drive circuit. 1 to 4, J ₁ , J ₂ , J ₃ , J ₄ , J ₅ , J ₆ , J ₇ , J ₈ ,
J ₂₁ , J ₂₂ , J ₄₁ , J ₄₂ , J ₆₁ , J ₆₂ , J ₈₁ , J ₈₂ ...... Josephson element, R _L1 , R _L2 , R _L3 ... Load resistance, R _I1 , R _I2 , R _I3 , R _I4 …… Input resistance, R _d1 , R _d2 , R _d3 , R _d4 …… Input / output separation resistance. In FIG. 5, J ₁ , J ₂ , J ₃ , J ₄ ... Josephson gate circuits, R ₁ , R ₂ , R ₃ .

Claims (3)

(57) [Claims] A first bias resistor connected between a bias supply terminal and a first terminal; a first Josephson element connected between the first terminal and a second terminal; 2
A second Josephson element connected between the first terminal and the ground, a first load resistor connected between the first terminal and the ground, and a connection between the second terminal and the first input terminal. A first input resistor, a second input resistor connected between the first terminal and the second input terminal, and a second bias connected between the bias supply terminal and a third terminal. A resistor, a third Josephson element connected between the third terminal and the fourth terminal, a fourth Josephson element connected between the fourth terminal and the ground, A second load resistor connected between a terminal and ground;
A third input resistor connected between the input terminals of
A fourth input resistor connected between the second input terminal and the first input terminal; a driven line connected between the second terminal and the fourth terminal; and a fourth input resistor inserted into the driven line. And a third load resistor. 2. The polarity switching type Josephson drive circuit according to claim 1, wherein a fifth Josephson element inserted between said first terminal and said second input resistance, and said second input resistance and A first input / output isolation resistor having one end connected between the fifth Josephson elements and the other end grounded, and a sixth Josephson inserted between the second terminal and the first input resistor A second input / output isolation resistor having one end connected between the first input resistance and the sixth Josephson element and the other end grounded; the third terminal and the fourth input resistance; A seventh Josephson element inserted between the fourth element and the fourth element;
A third input / output isolation resistor having one end connected between the input resistor and the seventh Josephson element and the other end grounded, and a third input / output isolation resistor inserted between the fourth terminal and the third input resistor. And a fourth input / output isolation resistor having one end connected between the third input resistance and the eighth Josephson element and the other end grounded. Switching type Josephson drive circuit. 3. The polarity switching type Josephson drive circuit according to claim 1, wherein said second Josephson element, said fourth Josephson element, said sixth Josephson element, and said eighth A polarity switching type Josephson drive circuit, comprising a plurality of Josephson elements connected in series instead of the Josephson elements.