Squid with coil inductively coupled to squid via mutual inductance

A technology of inductive coupling and coil, applied in the field of DC superconducting quantum interferometer, can solve the problems of reduced voltage swing, high input capacitance and low channel resistance FET, etc.

Active Publication Date: 2012-05-30
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0017] APF includes the following disadvantages: First, the peak-to-peak voltage swing is reduced due to the APF resistor acting as an additional shunt at low frequencies
But FETs with high input capacitance and low channel resistance are hard to find because most GaAs FETS are intended for high frequency applications (H. et al., IEEE Trans. Magn. 27, 2488-2490 (1991))

Method used

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  • Squid with coil inductively coupled to squid via mutual inductance
  • Squid with coil inductively coupled to squid via mutual inductance
  • Squid with coil inductively coupled to squid via mutual inductance

Examples

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Embodiment Construction

[0037] The equivalent circuit of the SBC is shown in Figure 4: dc-SQUID 2 passes through an ideal current source ( Figure 4a ) or voltage source ( Figure 4b )1 bias. In current bias mode, the current 3 through the series connected SQUID 2 and the feedback coil 4 is constant, but the voltage across the SQUID 2 is adjusted as the external magnetic field varies. In voltage bias mode, the SQUID 2 is biased by a constant voltage and the current 3 is modulated by an external magnetic field. Feedback coil 4 is inductively coupled to SQUID 2 via mutual inductance 5 so that additional flux occurs in the SQUID loop. The arrangement order of SQUID 2 and feedback coil 4 can be exchanged.

[0038] The new component SBC has the following special characteristics:

[0039] In current bias and voltage bias modes, the voltage (current)-flux curve (eg Figure 5a shown) and the current-voltage curves become asymmetrical. Taking the voltage bias mode as an example, the SQUID-loop Ф LOOP T...

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Abstract

A SQUID Bootstrap Circuit (SBC) consists of a mutually coupled dc-SQUID and a feedback coil. The SQUID and the coil are connected in series. The feedback coil, which can be made of a superconductor or of a normal metal, can be either integrated on the SQUID chip, or be placed separately next to the SQUID. Together, both SQUID and coil form a novel two-terminal device, which will be named SBC. The invention combines the advantages of both, APF and NC and avoids certain drawbacks thereof. With the help of this new design, the current or voltage -Phi characteristics of SQUID will be asymmetric and the equivalent dynamic resistance will be changed.

Description

technical field [0001] The present invention relates to a direct current superconducting quantum interference device (dc-SQUID) with connected coils which are inductively coupled to the SQUID via mutual inductance. Background technique [0002] The superconducting quantum interference device (SQUID) is an extremely sensitive sensor that can be used to detect magnetic flux or any physical quantity that can be converted into magnetic flux. A "dc-SQUID" biased to a DC power supply consists of a superconducting loop interrupted by two (identical) Josephson junctions. The output signal of the SQUID can be detected with the help of readout electronics. The main design challenge is amplifying very small output signals without introducing noise contributions from the preamplifier. [0003] Figure 1 describes two ways to bias dc-SQUID, current bias (current bias) and voltage bias (voltage bias). In current bias mode ( Figure 1a As shown), a constant current generated by an ideal ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R33/035
CPCG01R33/0356
Inventor 张懿H-J・克劳斯N・沃尔特斯A・奥芬豪瑟谢晓明王会武王永良董慧
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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