Superconductive SQUID offset reversal front-end circuit based on three end transformer and adjusting method thereof

A front-end circuit and transformer technology, applied in the direction of the magnitude/direction of the magnetic field, using superconducting devices for magnetic field measurement, etc., can solve problems such as changes in operating points, increased SQUID noise, and distortion of square wave bias current waveforms

Active Publication Date: 2014-03-12
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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AI Technical Summary

Problems solved by technology

However, the inductance of the primary side of the transformer will cause the waveform distortion of the square wave bias current, which will cause the SQUID operating point to change and increase the output noise
Especially when the bias inversion frequency is high, the distortion is more serious. At the same time, the long connecting line between the readout circuit and the SQUID will also cause the distortion of the AC square wave bias current, which will also increase the SQUID noise

Method used

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  • Superconductive SQUID offset reversal front-end circuit based on three end transformer and adjusting method thereof
  • Superconductive SQUID offset reversal front-end circuit based on three end transformer and adjusting method thereof

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Embodiment Construction

[0019] The substantive features and remarkable progress of the present invention will be further clarified through the description in conjunction with the accompanying drawings.

[0020] refer to figure 1 , The three-terminal transformer is the core of the front-end circuit, and the two primary sides 1, 2 and secondary side 3 of the three-terminal transformer are wound on the same magnetic ring. One primary side 1 of the three-terminal transformer is connected in series with resistor 6 to form a SQUID branch, and the other primary side 2 of the three-terminal transformer is connected in series with potentiometer 8 to form a waveform compensation branch, and one end of the secondary side of the transformer is grounded. , and the other end is connected to the preamplifier 5 .

[0021] After the output signals of the square wave signal generator 10 and the compensation signal generator 11 are synthesized by the adder 9 , they are connected to the SQUID branch through the bias ad...

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Abstract

The invention discloses a SQUID front-end circuit based on a three end transformer and an adjusting method thereof. The three end transformer is formed by three groups of coils which are winded on a same magnet ring. Primary sides (1), (2) of the three end transformer are used to realize SQUID magnetic flux signal transmission and square wave offset waveform compensation. A secondary side is mainly used to output a signal. Through adding synthetic waveform in SQUID parallel branch, the SQUID can be offset to be an ideal square wave offset current. The compensation branch can be used to compensate an offset carrier wave of an input preamplifier. The invention also provides the adjusting method of the front-end circuit. A main idea is low frequency adjusting-high frequency usage. The method comprises the following steps: offset current adjusting, working point determination, synthetic waveform adjusting, waveform compensation and high-frequency fine tuning.

Description

technical field [0001] The invention relates to a superconducting SQUID bias inversion front-end circuit, in particular to a three-terminal transformer in the front-end circuit. Background technique [0002] Superconducting quantum interference device (SQUID) is a magnetically sensitive device with extremely high sensitivity, which can realize the measurement of extremely weak magnetic signals (fT magnitude). According to different bias modes, the readout circuit can be divided into constant current bias and voltage bias, and currently the current bias readout circuit is widely used. The current bias can be DC or AC. When the SQUID is AC biased (that is, the bias is reversed), the preamplifier noise and low-frequency noise caused by critical current fluctuations (especially high-temperature SQUID) can be suppressed. In the bias current inversion circuit, the AC bias current generates a voltage drop through the SQUID, and is input to the input terminal of the preamplifier to...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R33/035
Inventor 荣亮亮王永良董慧王会武谢晓明江绵恒
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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