JP2003209299A - Current amplification means using superconducting quantum interference element and current detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current amplification means having a large gain and a high current resolution, and a current detector, regarding a superconducting quantum interference element amplifier which amplifies fine current signals. <P>SOLUTION: A multi-junction superconducting quantum interference element 1 formed by parallelly connecting DC type superconducting quantum interference elements is defined as a first circuit and is connected through a transmission resistor to a second circuit. The multi-junction superconducting quantum interference element 1 is constituted by parallelly connecting N pieces of DC-SQUIDs sharing a Josephson junction and a shunt resistor between the adjacent DC- SQUIDs. The current signal detected in the multi-junction superconducting quantum interference element 1 is changed to a large current and sent to the second circuit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting amplifier that amplifies a minute current signal, and more particularly to a minute signal detector that detects with high speed and high sensitivity.

[0002]

2. Description of the Related Art FIG. 11 shows a current amplifying means using a superconducting quantum interference device constructed by using a conventional technique. The direct current type superconducting quantum interference device (DC-SQUID) 34 consisting of two Josephson junctions and SQUID inductance is used as the first circuit, and is connected to the second circuit 11 via the transfer resistance 5. DC-SQUID34 is
A superconducting loop is formed by two Josephson junctions 2 and SQUID inductance 3. The input coil 4 and the feedback-modulation coil 7 are formed on the superconducting loop and are magnetically coupled to the SQUID inductance. A shunt resistor 6 is connected in parallel with the Josephson junction 2 in order to suppress the hysteresis of the current-voltage characteristics. Also, Josephson junction 2 and SQU
To suppress the resonance that occurs between the ID inductance 3,
The damping resistor 8 is connected in parallel with the SQUID inductance 3. The first circuit, the DC-SQUID 34, converts the minute input signal Iin input from the input coil into the large current signal I
It has the function of amplifying to a. The second circuit has the function of reading the current or the function of performing further arithmetic processing. Figure 12 shows the change in the critical current value of SQUID 34 with respect to the magnetic flux Φ penetrating the superconducting ring. Bias current I to SQUID34
When input signal Iin is input with b applied, the equation
The current Ia represented by (a) is sent to the second circuit 11. At this time, the input impedance of the circuit 11 is assumed to be negligible as compared with the resistance value Ra of the transfer resistor 5 and the resistance value Rs of the shunt resistor 6.

[0003]

[Equation 1]

[0004]

[Equation 2]

[0005]

[Equation 3]

[0006]

[Equation 4]

Here, Gin is the current gain of the SQUID 34, and is represented by the mutual inductance Min between the input coil 4 and the SQUID inductance 3 and the variation I _Φ of the critical current value with respect to the magnetic flux of the SQUID 34. β is the parameter expressed by equation (d). In order to supply a large current to the second circuit, it is important to increase the current gain Gin, that is, Min, _IΦ . One way to increase Min is to use SQUID with multi-turn input coil shown in Fig. 13.

[0008]

With respect to the current amplifying means and the current detector, it is necessary to increase the gain and improve the current resolution. Increasing the gain requires expanding I _Φ and Min. The maximum current value that can be supplied to the second circuit is DC
-Change in critical current of SQUID ΔIc. The amount of change in the critical current of DC-SQUID is several tens of μA. The mutual inductance Min of the one-turn input coil is about 100 pH. In other words, in one-turn DC-SQUID, Gin is several times larger, and considering β, a larger Gin is required. Also, Min can be increased by adopting a multi-turn input coil. However, the structure of the SQUID inductance becomes large, which makes it more susceptible to the effects of magnetic flux traps.
There is a problem that the self-inductance becomes large and it is not suitable for high-speed signal measurement. A magnetic flux trap is a phenomenon in which magnetic flux quanta are trapped in a superconductor when the superconductor transitions from the normal state to the superconducting state during the cooling process. The larger the magnetic field applied to the superconductor during cooling, the more magnetic flux traps are generated, and the larger the area of the superconductor, the easier it is to be trapped. The magnetic flux trap causes deterioration of the characteristics of the superconducting device and unstable operation such as reducing the critical current of the Josephson junction.

Further, the superconducting quantum interference device is an ultra low noise device, and its performance is generally limited by the driving circuit arranged at room temperature. Therefore, in order to improve the current resolution, it is necessary to reduce the contribution of the room temperature electronic circuit that limits its performance. In other words, it is necessary to convert to a sufficiently large voltage signal for the noise of the room temperature electronic circuit. Therefore, a large current-voltage conversion coefficient is required in the low temperature region.

[0010]

[Means for Solving the Problems] A multi-junction superconducting quantum interference device formed by connecting in parallel a direct current type superconducting quantum interference device (DC-SQUID) consisting of two Josephson junctions and a SQUID inductance Circuit and connect it to the second circuit via the transfer resistance. The multijunction SQUID1 is configured by connecting N DC-SQUIDs in parallel so that the Josephson junctions and shunt resistors are shared between adjacent DC-SQUIDs. The input coil of each DC-SQUID and the feedback-modulation coil are connected in series. The bias current Ib is
Inserted from DC-SQUID N / 2 located in the center. The second circuit has the function of reading the current or the function of further arithmetic processing. As a bias current supply method, DC-SQUID 1 and DC-SQUIDN located at both ends are applied as Ib_1 and Ib_2 evenly. Furthermore, as a method of supplying bias current, it is applied uniformly from the SQUID inductance of each DC-SQUID. Furthermore, as a method of supplying the bias current, it is applied evenly from the center of the damping resistance of each DC-SQUID. The second circuit is applied to the logic gate based on the single-flux-quantum theory (SFQ), which uses the flux quantum as an information carrier. A current detector is constructed by using the multijunction SQUID1 as the first circuit and connecting it to the second circuit, the DC-SQUID, via a transfer resistor. Moreover, the current detector is constructed by connecting the multi-junction SQUID as the first circuit and connecting the second circuit DC-SQUID to the series superconducting quantum interference device array in series through the transfer resistance. ．

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram of a current amplifying means using a superconducting quantum interference device (SQUID) showing a first embodiment of the present invention. The first is a multi-junction superconducting quantum interference device (multi-junction SQUID) 1 which is formed by connecting a plurality of DC superconducting quantum interference devices (DC-SQUID) in parallel, each consisting of two Josephson junctions and SQUID inductances. As a circuit, it is connected to the second circuit 11 via the transfer resistor 5. The multijunction SQUID1 is composed of the DC-SQUID shown in Fig. 2. DC-SQUID forms a superconducting loop by two Josephson junctions 2 and SQUID inductance 3. Input coil 4 and feedback-modulation coil 7
Is formed on the SQUID inductance 3 and magnetically coupled to the superconducting loop. A shunt resistor 6 is connected in parallel with the Josephson junction 2 in order to suppress the hysteresis of the current-voltage characteristics. Moreover, in order to suppress the resonance generated between the Josephson junction 2 and the SQUID inductance 3, the damping resistor 8 is connected in parallel with the SQUID inductance 3.
The multi-junction SQUID1 has N DC-SQs so that the adjacent DC-SQUIDs share the Josephson junction 2 and the shunt resistor 6.
It is constructed by connecting UIDs in parallel. Each DC-SQUID
The input coil and feedback-modulation coil of are connected in series. The bias current Ib is inserted from the DC-SQUID N / 2 located at the center. The first circuit, the multi-junction SQUID1, has the function of amplifying the minute input signal Iin input from the input coil into a large current signal Ia. The second circuit has the function of reading the current value or the function of performing further arithmetic processing. Here, the ratio (transmission coefficient) of Ia sent to the second circuit with respect to the input current Iin will be described.
As for the critical current value of each Josephson junction, the critical current value of the Josephson junction excluding both ends is set to be twice that of the two Josephson junctions at both ends. For each shunt resistance, the shunt resistance excluding both ends is doubled of the two shunts at both ends. Also, each SQUID inductance is assumed to be equal. A bias current Ib_N of the same magnitude is applied to each DC-SQUID. Figure 3 shows the relationship between the input current Iin and the critical current value of the multijunction SQUID1. At Min Iin / Φ0, a large change in critical current is obtained with N times the period. The operating point is fixed at the steep point A in Fig. 3 by adding a current from the feedback-modulation coil. Ic_max is applied to the bias current Ib. In that state, when the input signal In is input, the current Ia sent to the second circuit 11 is expressed by the equation (1).

[0012]

[Equation 5]

[0013]

[Equation 6]

[0014]

[Equation 7]

[0015]

[Equation 8]

Here, the resistance value Ra of the transmission resistance 5 and the multi-junction
Compared with the operating resistance of SQUID (= Rs / (2N + 2)), the second circuit 1
The input impedance of 1 is assumed to be negligible. Here, Rs is the resistance value per shunt resistor 6. Gin is the current gain of SQUID1 alone, and the mutual inductance M between input coil 4 and SQUID inductance 3
Change in critical current value with respect to magnetic flux of in and multijunction SQUID1 I
It is represented by _Φ . β is the parameter expressed by Eq. (4). In this example, the large change in critical current of the multijunction SQUID is used, and a very large current gain can be obtained with respect to the input current. As a result, a large current can be transmitted to the second circuit, which is the latter stage. When a logic gate based on the Single Flux Quantum Theory (SFQ), which uses flux quanta as information carriers, is used as the second circuit, not only high-speed SFQ but also high-sensitivity and high-resolution arithmetic processing is possible. To This embodiment can be applied to a preamplifier of an A / D converter. Figure 4 (a) is a plan view showing the structure of the multi-junction SQUID. In addition, FIG. 4B shows an enlarged view of an N / 2 DC-SQUID to which the bias wiring 44 is connected. In the equivalent circuit shown in Fig. 1, each DC-SQUID is composed of one SQUID inductance. In a real device,
As shown in (a) and 4 (b), it is composed of two upper and lower SQUID inductances 3. A damping resistor 8 is connected in parallel to the upper and lower SQUID inductances. The Josephson junction 2 is formed on the SQUID inductance above. Then, the upper electrode of the Josephson junction and the lower SQUID
Inductance is Josephson junction? Connection part (contact hole) 41 of upper wiring layer, SQUID inductance?
The upper wiring layer 91 is connected through the connection portion (contact hole) 43 of the upper wiring layer.

The input coil 4 and the feedback-modulation coil are arranged above the SQUID inductance and magnetically coupled. In the multijunction SQUID with this configuration, a large current gain Gin can be obtained even with a one-turn input coil. Since it is not necessary to use a multi-turn coil, it can be composed of SQUID inductances with a narrow SQUID line width, and it is possible to prevent magnetic flux traps in the SQUID inductance, which causes characteristic deterioration. As a result, the current can be stably sent to the second circuit with a large current gain. Furthermore, the self-inductance of the input coil can be made smaller than that of the multi-turn coil, which is suitable for high-speed signal measurement. In this embodiment, the current-
An example of a tunnel junction type Josephson junction (for example, Nb / Al-AlOx / Nb) that produces hysteresis in voltage characteristics is shown. In addition to the tunnel junction type Josephson junction, a Josephson junction that does not cause hysteresis in current-voltage characteristics, such as the grain boundary junction type Josephson junction using YBCO superconducting thin film, can be used as a current amplification means with the same effect. can get. In this case, the shunt resistor is unnecessary. (Second Embodiment) FIG. 5 is a block diagram of a current amplifying means using a superconducting quantum interference device showing a second embodiment of the present invention. A multi-junction SQUID1 formed by connecting two Josephson junctions and a DC-SQUID consisting of SQUID inductances in parallel is used as the first circuit, and is connected to the second circuit 11 via the transfer resistance 5. The multijunction SQUID1 is composed of the DC-SQUID shown in Fig. 2. DC-SQUID consists of two Josephson junctions 2 and SQ
A UID inductance 3 forms a superconducting loop.
An input coil 4 and a feedback-modulation coil 7 are formed on the SQUID inductance 3 and magnetically coupled to the superconducting loop. Electric current
-A shunt resistor 6 is connected in parallel with the Josephson junction 2 to suppress the hysteresis of the voltage characteristics. Moreover, in order to suppress the resonance generated between the Josephson junction 2 and the SQUID inductance 3, the damping resistor 8 is connected in parallel with the SQUID inductance 3. The multijunction SQUID1 is constructed by connecting N DC-SQUIDs in parallel so that the Josephson junction 2 and the shunt resistor 6 are shared between adjacent DC-SQUIDs. The input coil of each DC-SQUID and the feedback-modulation coil are connected in series. Bias current is evenly distributed from both ends of DC-SQUID 1 and DC-SQUID N to Ib_1,
It is applied as Ib_2. The multi-junction SQUID12 has DC-
It consists of N DC-SQUIDs connected in parallel so that the SQUID Josephson junction 2 and the shunt resistor 6 are shared. The input coil of each DC-SQUID and the feedback-modulation coil are connected in series. (Third Embodiment) FIG. 6 is a block diagram of a current amplifying means using a superconducting quantum interference device showing a third embodiment of the present invention. A multi-junction SQUID1 formed by connecting two Josephson junctions and a DC-SQUID consisting of SQUID inductances in parallel is used as the first circuit, and is connected to the second circuit 11 via the transfer resistance 5. The multijunction SQUID1 is composed of the DC-SQUID shown in Fig. 2. DC-SQUID consists of two Josephson junctions 2 and SQ
A UID inductance 3 forms a superconducting loop.
An input coil 4 and a feedback-modulation coil 7 are formed on the SQUID inductance 3 and magnetically coupled to the superconducting loop. Electric current
-A shunt resistor 6 is connected in parallel with the Josephson junction 2 to suppress the hysteresis of the voltage characteristics. Moreover, in order to suppress the resonance generated between the Josephson junction 2 and the SQUID inductance 3, the damping resistor 8 is connected in parallel with the SQUID inductance 3. The multijunction SQUID1 is constructed by connecting N DC-SQUIDs in parallel so that the Josephson junction 2 and the shunt resistor 6 are shared between adjacent DC-SQUIDs. The input coil of each DC-SQUID and the feedback-modulation coil are connected in series. Bias current is D
It is applied uniformly from the SQUID inductance of C-SQUID. (Fourth Embodiment) FIG. 7 is a block diagram of a current amplifying means using a superconducting quantum interference device showing a third embodiment of the present invention. A multi-junction SQUID1 formed by connecting two Josephson junctions and a DC-SQUID consisting of SQUID inductances in parallel is used as the first circuit, and is connected to the second circuit 11 via the transfer resistance 5. The multijunction SQUID1 is composed of the DC-SQUID shown in Fig. 2. DC-SQUID consists of two Josephson junctions 2 and SQ
A UID inductance 3 forms a superconducting loop.
An input coil 4 and a feedback-modulation coil 7 are formed on the SQUID inductance 3 and magnetically coupled to the superconducting loop. Electric current
-A shunt resistor 6 is connected in parallel with the Josephson junction 2 to suppress the hysteresis of the voltage characteristics. Moreover, in order to suppress the resonance generated between the Josephson junction 2 and the SQUID inductance 3, the damping resistor 8 is connected in parallel with the SQUID inductance 3. The multijunction SQUID1 is constructed by connecting N DC-SQUIDs in parallel so that the Josephson junction 2 and the shunt resistor 6 are shared between adjacent DC-SQUIDs. The input coil of each DC-SQUID and the feedback-modulation coil are connected in series. Bias current is D
It is applied evenly from the center of the damping resistance of the C-SQUID. In this embodiment, the Baice current lines applied to each DC-SQUID can be integrated into one line. Therefore, it becomes easy to supply the bias current from the room temperature electronic circuit. (Fifth Embodiment) FIG. 8 is a block diagram of a current detector using a superconducting quantum interference device according to a fifth embodiment of the present invention.
The multijunction SQUID1 shown in the first embodiment is used as the first circuit, and is connected to the second circuit, the DC-SQUID31, via the transfer resistor 5. Further, the multi-junction SQUID1 and DC-SQUID31 are driven by the room temperature drive circuit 34. The first circuit DC-SQUID31 is a multi-junction
It has the function of converting the current detected and amplified by SQUID1 into voltage. DC-SQUID31 consists of two Josephson junctions 12 and SQU
A superconducting loop is formed by the ID inductance 13.
An input coil 14 and a feedback-modulation coil 17 are formed on the superconducting loop and magnetically coupled to the SQUID inductance. Furthermore, the input coil and feedback-modulation coil are magnetically coupled to the SQUID inductance. The shunt resistor 16 has a Josephson junction to suppress the hysteresis of the current-voltage characteristics.
It is connected in parallel with 12. Also, Josephson junction 12
A damping resistor 18 is connected in parallel with the SQUID inductance 13 in order to suppress the resonance that occurs between the SQUID inductance 13. Multi-junction SQUID1 and DC-SQUID31
Is driven by the room temperature drive circuit 33 and outputs the input current Iin as a voltage signal Vout. In the present embodiment, a room temperature drive circuit uses a Flux locked loop circuit having a function of linearizing a DC-SQUID having periodicity in magnetic flux-critical current characteristics and magnetic flux-voltage characteristics and expanding a measurement range. Here, the driving method of the current detector is explained. Multi-junction SQ
Figure 3 shows the relationship between the input current Iin of UID1 and the critical current value. The operating point is fixed at the steep point A in Fig. 3 by adding a current from the feedback-modulation coil. The bias current is I
Apply c_max. In that state, when the input signal In is input, the current Ia sent to the DC-SQUID 31 is expressed by equation (1). Here, it is assumed that the input impedance of the second circuit 11 is negligible compared with the resistance value Ra of the transfer resistance 5 and the operating resistance (= Rs / (2N + 2)) of the multijunction SQUID. Here, Rs is the resistance value per shunt resistor 6.
On the other hand, Fig. 9 shows the magnetic flux-voltage characteristics of DC-SQUID31. Return-
An offset current Im is added from the modulation coil 17 and bias is applied to point B where the magnetic flux-voltage is steep. The current-voltage sensitivity (gain) Ga of DC-SQUID is expressed by Eq. (5). Also, assuming that the characteristic voltage noise of the DC-SQUID is SV_s and the input conversion voltage noise of the drive circuit is Ve, the current noise In_a when converted to the current flowing in the input coil is expressed by equation (7). Multi-junction array 1
And the total gain Gt of DC-SQUID31 is expressed by equation (8).

[0018]

[Equation 9]

[0019]

[Equation 10]

[0020]

[Equation 11]

[0021]

[Equation 12]

The output voltage Vs of the DC-SQUID 31 changes according to the input current Iin. In the room temperature drive circuit 33, calculations such as amplification and integration are performed. The room temperature drive circuit 33 is designed so that the sum of the magnetic flux that is multijunction SQUID coupled by the input current Iin and the feedback-modulation coil that is multijunction SQUID coupled is always kept constant.
The feedback current If is supplied to the feedback-modulation coil of the multijunction SQUID1 from. As a result, the room temperature drive circuit 33 outputs the output signal Vout proportional to the input current Iin. In this embodiment, DC-S
Since QUID31 functions as a low noise current-voltage converter, improvement in sensitivity can be expected. If the characteristic current noise of the multi-junction array is SI_s, the total current resolution In_in is given by equation (9).

[0023]

[Equation 13]

(Sixth Embodiment) FIG. 10 shows a sixth embodiment of the present invention.
The block diagram of the electric current detector using the superconducting quantum interference element which shows an Example is shown. First, the multi-junction SQUID1 shown in the first embodiment is used.
The second circuit is connected to the series-connected superconducting quantum interference device array (series SQUID array) via the transfer resistance 5. Series SQUID array 32 is a multi-junction SQU
It has the function of converting the current detected and amplified by ID1 into voltage. Multi-junction SQUID1 and DC-SQUID32 are room temperature drive circuits 33
It is connected to and outputs the input current Iin as a voltage signal Vout. The serial SQUID array 32 is composed of multiple DC-SQUIDs and can be obtained by connecting them in series. Each DC-SQUID is
A superconducting loop is formed by the two Josephson junctions 22 and the SQUID inductance 23. An input coil 24 and a feedback-modulation coil 27 are formed on the superconducting loop and are magnetically coupled to the SQUID inductance. A shunt resistor 26 is connected in parallel with the Josephson junction 22 to suppress the hysteresis of the current-voltage characteristics. Moreover, in order to suppress the resonance generated between the Josephson junction 22 and the SQUID inductance 13, the damping resistor 28 is used to suppress the resonance.
It is connected in parallel with 3. Input coil of each DC-SQUID,
And the feedback-modulation coil is connected in series. Multi-junction S
QUID1 and DC-SQUID31 are driven by the room temperature drive circuit 33, and output the input current Iin as the voltage signal Vout.
In the present embodiment, the room temperature drive circuit has a function of linearizing a SQUID having periodicity in the magnetic flux-critical current characteristic and the magnetic flux-voltage characteristic and having a function of expanding the measurement range.
It uses op circuit. The driving method of the current detector is the same as in the fifth embodiment. SQUID arrays provide very large modulation voltages. As a result, a large gain Ga is obtained.
As can be seen from equation (9), a large Ga reduces the noise contribution of the room temperature electronic circuit. In this embodiment, very high current resolution can be provided.

[0025]

EFFECTS OF THE INVENTION By using a multijunction superconducting quantum interference device (multijunction SQUID) formed by connecting DC superconducting quantum interference devices (DC-SQUIDs) in parallel as a current amplifier, By utilizing the large change in critical current, a very large current gain can be obtained for the input current. As a result, a large current can be transmitted to the second circuit, which is the latter stage. In addition, as the second circuit, the single flux quantum theory (SF
When a logic gate based on Q) is used, not only high-speed SFQ formation but also high-sensitivity and high-resolution arithmetic processing is possible. This embodiment can be applied to a purine amplifier of an A / D converter. Furthermore, in the multijunction SQUID, a large current gain can be obtained even with a one-turn input coil. Therefore, the SQUID inductance can be configured with a narrow line width, and the magnetic flux trap in the SQUID inductance, which causes characteristic deterioration, can be prevented. As a result, the current can be stably sent to the second circuit with a large current gain. It is suitable for high-speed signal detection because the self-inductance of the input coil can be reduced. The multi-junction SQUID1 is the first circuit, and the second circuit is the DC-SQUID via the transfer resistance.
By configuring a current detector by connecting to
-Since SQUID31 functions as a low noise current-voltage converter, improved sensitivity can be expected. In addition, the multi-junction SQUID is the first circuit, and the second circuit DC-
By constructing a current detector by connecting a plurality of SQUIDs connected in series to a superconducting quantum interference device array (series SQUID array), a very large modulation voltage is applied to the subsequent series SQUID array, and a large gain is obtained. Ga is obtained. As a result, very high current resolution can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of current amplification means using a superconducting quantum interference device according to a first embodiment.

[Fig. 2] DC-SQUID constituting a multi-junction superconducting quantum interference device
Equivalent circuit diagram of.

FIG. 3 shows the change in the critical current with respect to the input current Iin of the multijunction superconducting quantum interference device.

4A is a plan view showing the structure of a multijunction superconducting quantum interference device, and FIG. 4B is an enlarged view of a part thereof.

FIG. 5 is a current amplification means using a superconducting quantum interference device according to the second embodiment.

FIG. 6 is a current amplification means using a superconducting quantum interference device showing a third embodiment.

FIG. 7 is a current amplification means using a superconducting quantum interference device showing a fourth embodiment.

FIG. 8 is a configuration diagram of a current detector using a superconducting quantum interference device showing a fifth embodiment.

FIG. 9: Magnetic flux-voltage characteristics of DC-SQUID.

FIG. 10 is a configuration diagram of a current detector using a series superconducting quantum interference device array according to a fifth embodiment.

FIG. 11 is a current amplification means using a superconducting quantum interference device showing a conventional example.

FIG. 12 shows the change in critical current with respect to the input current Iin of DC-SQUID.

FIG. 13 is a plan view showing the configuration of a DC-SQUID having a multi-loop coil.

[Explanation of symbols]

1 ... Multi-junction superconducting quantum interference device 2, 12, 22 ... Josephson junction 3, 13, 23 ... SQUID inductance 4, 14, 24 ... Input coil 5 ... Transfer resistance 6, 16, 26 ... Shunt resistors 7, 17, 27 ... Feedback-modulation coils 8, 18, 28 ... Damping resistors 9, 91 ... Upper wiring layer 11 ... Second circuits 31, 34・ ・ ・ DC-SQUID 32 ・ ・ ・ Series superconducting quantum interference device array (series SQUID
Array) 33 ... Room temperature driving circuit 41 ... Josephson junction-connection part of upper wiring layer (contact hole) 42 ... SQUID inductance-connection part of resistance layer (contact hole) 43 ... SQUID inductance- Connection part of upper wiring layer (contact hole) 44 ... Bias wiring

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiichi Tanaka             1-8 Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture             Ceremony Company SII RDI Center             Within (72) Inventor Tatsuji Ishikawa             1-8 Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture             Ico Instruments Co., Ltd. (72) Inventor Kazuo Kane             1-8 Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture             Ico Instruments Co., Ltd. F-term (reference) 2G017 AA05 AD34                 2G025 AA00 AB05 AC04                 4M113 AA04 AA14 AA25 AC08 AC33                       AD21 CA31

Claims (7)

[Claims] 1. A superconducting quantum interference device which uses a multi-junction superconducting quantum interference device in which a plurality of direct current type superconducting quantum interference devices are connected in parallel as a current amplifier and which transfers a current to a second circuit via a transfer resistor. Is a current amplification means using the DC-type superconducting quantum interference device having two Josephson junctions and an S
A superconducting loop is formed by the QUID inductance, and an input coil for signal input magnetically coupled to the superconducting loop, a feedback-modulation coil, and a Josephson junction are connected in parallel to suppress hysteresis of current-voltage characteristics. The multi-junction superconducting quantum interference device is provided with a shunt resistor and a damping resistor connected in parallel with the SQUID inductance in order to suppress resonance generated between the Josephson junction and the SQUID inductance. The superconducting quantum interference device is constructed by connecting in parallel so as to share the Josephson junction and shunt resistance, and the input coil and feedback-modulation coil of each DC type superconducting quantum interference device are connected in series. The bias current of the multijunction superconducting quantum interference device is the superconductivity inserted from the DC-SQUID located in the center. Current amplification means using quantum interference device. 2. A superconducting quantum interference device which uses a multijunction superconducting quantum interference device in which a plurality of direct current type superconducting quantum interference devices are connected in parallel as a current amplifier and which transfers a current to a second circuit via a transfer resistor. Is a current amplification means using the DC-type superconducting quantum interference device having two Josephson junctions and an S
The QUID inductance forms a superconducting loop,
The input coil for signal input magnetically coupled to the superconducting loop, the feedback-modulation coil, the shunt resistance connected in parallel with the Josephson junction to suppress the hysteresis of the current-voltage characteristics, the Josephson junction and the SQUID inductance. The multi-junction superconducting quantum interference device is provided with a SQUID inductance and a damping resistor connected in parallel in order to suppress resonance that occurs between the direct current superconducting quantum interference devices. And a shunt resistor connected in parallel so as to share the input coil of each DC type superconducting quantum interference device and the feedback-modulation coil in series, and a bias of the multijunction superconducting quantum interference device. For the current, use the superconducting quantum interference devices that are evenly inserted from the two DC superconducting quantum interference devices located at both ends. Current amplification means. 3. A superconducting quantum interference device which uses a multijunction superconducting quantum interference device in which a plurality of direct current type superconducting quantum interference devices are connected in parallel as a current amplifier, and which transfers a current to a second circuit via a transfer resistor. Is a current amplification means using the DC-type superconducting quantum interference device having two Josephson junctions and an S
The QUID inductance forms a superconducting loop,
The input coil for signal input magnetically coupled to the superconducting loop, the feedback-modulation coil, the shunt resistance connected in parallel with the Josephson junction to suppress the hysteresis of the current-voltage characteristics, the Josephson junction and the SQUID inductance. The multi-junction superconducting quantum interference device is provided with a SQUID inductance and a damping resistor connected in parallel in order to suppress resonance that occurs between the direct current superconducting quantum interference devices. And a shunt resistor connected in parallel so as to share the input coil of each DC type superconducting quantum interference device and the feedback-modulation coil in series, and a bias of the multijunction superconducting quantum interference device. For the current, use a superconducting quantum interference device that is evenly inserted from the SQUID inductance of each DC superconducting quantum interference device. Current amplifying means is. 4. A superconducting quantum interference device which uses a multi-junction superconducting quantum interference device in which a plurality of direct current type superconducting quantum interference devices are connected in parallel as a current amplifier and which transfers current to a second circuit via a transfer resistor. Is a current amplification means using the DC-type superconducting quantum interference device having two Josephson junctions and an S
The QUID inductance forms a superconducting loop,
The input coil for signal input magnetically coupled to the superconducting loop, the feedback-modulation coil, the shunt resistance connected in parallel with the Josephson junction to suppress the hysteresis of the current-voltage characteristics, the Josephson junction and the SQUID inductance. The multi-junction superconducting quantum interference device is provided with a SQUID inductance and a damping resistor connected in parallel in order to suppress resonance that occurs between the direct current superconducting quantum interference devices. And a shunt resistor connected in parallel so as to share the input coil of each DC type superconducting quantum interference device and the feedback-modulation coil in series, and a bias of the multijunction superconducting quantum interference device. The current is a superconducting quantum interference element that is evenly inserted from the center of the damping resistor of each DC superconducting quantum interference device. Current amplification means using a child. 5. A preamplifier for current amplification for arithmetic processing of the multijunction superconducting quantum interference device, wherein a logic gate based on a single flux quantum theory (SFQ) using a flux quantum as an information carrier is connected as the second circuit. 5. A current amplification means using a superconducting quantum interference device according to any one of claims 1 to 4, characterized by: 6. A superconducting loop is formed by two Josephson junctions and a SQUID inductance as the second circuit of the current amplifying means using the superconducting quantum interference device according to claim 1. , An input coil connected to the transfer resistance magnetically coupled to the superconducting loop, and a current
-A shunt resistor connected in parallel with the Josephson junction in order to suppress the hysteresis of the voltage characteristics, and a DC resistance with a damping resistor connected in parallel with the SQUID inductance in order to suppress the resonance that occurs between the Josephson junction and the SQUID inductance. Detector using a superconducting quantum interference device, characterized by comprising a current read-out means consisting of a quantum quantum interference device and a room temperature drive circuit. 7. An input coil connected to the transfer resistance is provided as the second circuit of the current amplifying means using the superconducting quantum interference device according to claim 1, and is connected in series. A current detector using a superconducting quantum interference device, comprising a series-connected superconducting quantum interference device array composed of a plurality of DC superconducting quantum interference devices, and a current reading means composed of a room temperature driving circuit.