WO2017128706A1 - 一种直读式磁通调制读出电路及方法 - Google Patents

一种直读式磁通调制读出电路及方法 Download PDF

Info

Publication number
WO2017128706A1
WO2017128706A1 PCT/CN2016/096327 CN2016096327W WO2017128706A1 WO 2017128706 A1 WO2017128706 A1 WO 2017128706A1 CN 2016096327 W CN2016096327 W CN 2016096327W WO 2017128706 A1 WO2017128706 A1 WO 2017128706A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
magnetic flux
squid
modulation
direct
Prior art date
Application number
PCT/CN2016/096327
Other languages
English (en)
French (fr)
Inventor
荣亮亮
张懿
蒋坤
王永良
伍俊
谢晓明
Original Assignee
中国科学院上海微***与信息技术研究所
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 中国科学院上海微***与信息技术研究所 filed Critical 中国科学院上海微***与信息技术研究所
Publication of WO2017128706A1 publication Critical patent/WO2017128706A1/zh

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
    • G01R33/0354—SQUIDS
    • G01R33/0356—SQUIDS with flux feedback
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment

Definitions

  • the present invention relates to the field of magnetic sensor technology, and in particular, to a direct reading flux modulation readout circuit and method.
  • Superconducting Quantum Interference Device is a highly sensitive magnetic sensor that can be used to construct superconducting magnetic sensors. It is widely used in the field of weak magnetic field detection such as biological magnetic field, earth magnetic field anomaly, very low field nuclear magnetic resonance and geophysical exploration. Its detection sensitivity has reached the level of Feite (10 -15 Tesla). SQUID magnetic sensor is an important magnetic sensor device for extreme detection and scientific research, and has high scientific research and application value.
  • SQUID works in the low frequency band (less than 10Hz), and the low frequency noise performance is an important performance indicator that determines the application effect.
  • the low frequency noise of the preamplifier and the critical current fluctuation of the SQUID chip are the main sources of noise for the low frequency noise of the SQUID magnetic sensor, which seriously restricts the application of SQUID in the field of low frequency magnetic measurement (especially for biomagnetic detection and geophysical exploration applications).
  • a method for reducing low frequency noise of a magnetic sensor based on a magnetic flux modulation technique modulates a low frequency signal to be measured at a high frequency by adding a higher frequency modulation magnetic flux to the sensor (generally about 100 kHz). Therefore, the low frequency noise segment of the preamplifier is avoided to achieve low frequency noise suppression; at the same time, the method can also effectively suppress the in-phase low frequency noise introduced by the critical current fluctuation (especially for the high temperature SQUID).
  • a transformer is introduced here between the SQUID and the preamplifier. As shown in FIG.
  • the magnetic flux modulation circuit 1 for implementing the method includes a SQUID device 11, a transformer 12, a preamplifier 13, a demodulator 14, an integrator 15, a modem signal generator 16, a feedback resistor Rf, Feedback coil Lf and resistance.
  • the SQUID device 11 is connected to the primary side of the transformer 12 via a resistor, and the secondary output of the transformer 12 is connected to the preamplifier 13.
  • the output of the preamplifier 13 is connected to the demodulator 14 for demodulation, and the demodulated output is output.
  • the magnetic flux is fed back to the SQUID device 11 through the feedback resistor Rf and the feedback coil Lf, thereby ensuring that the SQUID flux operating point does not change, and the signal modulating the magnetic flux is generated by the modem signal generator 16.
  • the feedback coil Lf is also sent to modulate the magnetic flux operating point of the SQUID, and the modem signal generator 16 also generates a synchronous demodulated signal to be sent to the demodulator 14.
  • the introduction of transformer 12 has three negative effects: (1) the SQUID output voltage signal amplitude is reduced (transformer source side load); (2) the high frequency harmonic components of the SQUID output signal are filtered out, resulting in the operating point (3)
  • the transformer itself has thermal noise.
  • the noise of the flux modulation readout circuit is not better than that of the direct readout readout circuit (especially for the large ⁇ c SQUID chip).
  • the introduction of the transformer 12 also leads to The circuit structure is more complicated and the usability is degraded.
  • an object of the present invention is to provide a direct-reading magnetic flux modulation readout circuit and method for solving the thermal noise and signal amplitude reduction brought about by the introduction of a transformer in the prior art. At the working point become smaller and other issues.
  • the present invention provides a direct reading flux modulation readout circuit, the direct read flux modulation readout circuit comprising at least:
  • a SQUID device for detecting a measured magnetic flux signal and converting it into a corresponding electrical signal output
  • a preamplifier connected to the SQUID device, for amplifying an electrical signal output by the SQUID device
  • a high pass filter coupled to the preamplifier for filtering DC output and low frequency noise of the preamplifier output
  • a modem signal generator for generating a flux modulation signal and a magnetic flux demodulation signal
  • a demodulator connected to the high pass filter and the modulation and demodulation signal generator, and demodulating an output signal of the high pass filter according to the magnetic flux demodulation signal;
  • An integrator coupled to the demodulator, integrating an output signal of the demodulator, and outputting a response voltage signal proportional to the measured magnetic flux signal;
  • a feedback module connected to the integrator and the modulation and demodulation signal generator, and the response voltage signal is modulated by the magnetic flux modulation signal and fed back to the SQUID device to lock the operating point.
  • the high pass filter comprises a capacitor connected between the preamplifier and the demodulator, and a resistor connected at one end to the capacitor output and grounded at the other end.
  • the feedback module includes a feedback resistor and a feedback coil; one end of the feedback resistor is connected to the output end of the integrator, and the other end is connected to the feedback coil; the other end of the feedback coil is grounded, the feedback resistor And the magnetic flux modulation signal is connected between the feedback coils.
  • the flux modulation signal is a square wave signal having a duty cycle of 50%.
  • the present invention provides a readout method for the above-described direct-reading magnetic flux modulation readout circuit, and the direct-reading magnetic flux modulation readout method includes at least:
  • the working point of the SQUID device is set to jump between the first working point and the second working point by a magnetic flux modulation signal, and the changing trend of the first working point and the second working point is opposite, and the detected
  • the measured magnetic flux signal is converted into a corresponding electrical signal, and the electrical signal is amplified and subjected to high-pass filtering to filter out low-frequency noise, and isolate the DC amount, and then demodulate and integrate
  • the SQUID device is then fed back to form a SQUID flux lock loop to lock the operating point.
  • the first working point is different from the second working point by a half cycle.
  • the direct reading type magnetic flux modulation readout circuit and method of the present invention have the following beneficial effects:
  • SQUID device and readout circuit are directly connected to realize flux modulation, and noise suppression is superior; modulation frequency selection is wider, which is beneficial to signal-to-noise ratio improvement; overcomes the load effect of traditional flux modulation circuit transformer, SQUID flux voltage The curve has no attenuation.
  • a high-pass filter is introduced after the output of the preamplifier to ensure that the output bias voltage and low frequency noise of the preamplifier are isolated while the signal passes.
  • the SQUID device is matched with the preamplifier, which overcomes the bandwidth limitation problem of SQUID and transformer matching in the traditional flux modulation circuit, no loss of higher harmonic components, and less distortion of SQUID flux-voltage curve.
  • Fig. 1 is a schematic view showing the structure of a magnetic flux modulating circuit in the prior art.
  • FIG. 2 is a schematic view showing the structure of a direct reading type magnetic flux modulation readout circuit of the present invention.
  • Figure 3 shows a schematic diagram of a typical SQUID flux-voltage transfer characteristic.
  • FIG. 4 is a schematic view showing the principle of the direct reading type magnetic flux modulation reading method of the present invention.
  • the present invention provides a direct-reading magnetic flux modulation readout circuit 2
  • the direct-reading magnetic flux modulation readout circuit 2 includes at least:
  • SQUID device 21 preamplifier 22, high pass filter 23, modem signal generator 24, demodulator 25, integrator 26, feedback module 27.
  • the SQUID device is used to detect a measured magnetic flux signal and convert it into a corresponding electrical signal output.
  • the SQUID device is a superconducting ring formed by two superconducting Josephson junctions connected in parallel, and leads are terminated at both ends of the Josephson junction, and a certain bias current is applied, and the voltage across the SQUID device is induced.
  • the characteristics of the magnetic field change, the typical SQUID flux-voltage transmission characteristic curve is shown in Figure 3.
  • One end of the SQUID device is grounded, and the other end is connected to the input end of the preamplifier 22, and the detected measured magnetic flux signal is converted into a corresponding electrical signal and output to the preamplifier 22.
  • the preamplifier 22 is connected to the SQUID device to amplify an electrical signal output by the SQUID device 21.
  • the preamplifier 22 has a high input impedance, and the SQUID flux-voltage conversion coefficient is not reduced by the load effect, and the preamplifier 22 has a wide bandwidth and does not have a SQUID flux-voltage curve. Produces high harmonic distortion.
  • the high pass filter 23 is connected to the preamplifier 22 for filtering out the direct current and low frequency noise output by the preamplifier 22.
  • the specific structure of the high-pass filter 23 is not limited, and any circuit structure capable of realizing the high-pass filtering function is included.
  • the high pass filter 23 includes a capacitor C and a first resistor R1 connected between an output end of the preamplifier 22 and an input end of the demodulator 25; One end of the first resistor R1 is connected between the capacitor C and the demodulator 25, and the other end is grounded.
  • the modulation and demodulation signal generator 24 is used to generate a magnetic flux modulation signal and a magnetic flux demodulation signal.
  • the modulation and demodulation signal generator 24 respectively generates a magnetic flux modulation signal and a magnetic flux demodulation signal corresponding to the magnetic flux modulation signal.
  • the magnetic flux modulation signal is a square wave signal with a duty ratio of 50%, so that the operating point jumps between the first working point and the second working point, wherein the first working point and The trend of change in the second working point is reversed.
  • the demodulator 25 is connected to the high pass filter 23 and the modulation and demodulation signal generator 24, and outputs an output signal of the high pass filter 23 according to the magnetic flux demodulation signal 24. Perform demodulation.
  • the integrator 26 is connected to the demodulator 25, integrates an output signal of the demodulator 25, and outputs a response voltage signal Vf proportional to the measured magnetic flux signal. .
  • the feedback module 27 is connected to the integrator 26 and the modulation and demodulation signal generator 24, and the response voltage signal Vf is modulated by the magnetic flux modulation signal and fed back to the SQUID. Device 21, thereby locking the operating point.
  • the feedback module 27 includes a feedback resistor Rf and a feedback coil Lf, one end of the feedback resistor Rf is connected to the output end of the integrator 26, and the other end is connected to the feedback coil Lf, and the feedback coil Lf is another One end is grounded, and the magnetic flux modulation signal is connected between the feedback resistor Rf and the feedback coil Lf.
  • the response voltage signal Vf and the magnetic flux modulation signal respectively generate a feedback current through the feedback resistor Rf and the second resistor R2, and the feedback current generates a mutual inductance Mf with the SQUID device 21 through the feedback coil Lf, and the mutual inductance Mf cancels the measured flux signal so that the entire negative feedback loop is stable and the operating point is locked.
  • the above-described direct reading type magnetic flux modulation readout circuit 2 operates as follows:
  • the working point of the SQUID device is set to jump between the first working point and the second working point by a magnetic flux modulation signal, and the changing trend of the first working point and the second working point is opposite, and the detected
  • the magnetic flux signal is converted into a corresponding electrical signal, and the electrical signal is amplified and subjected to high-pass filtering to filter out low-frequency noise, and the DC amount is isolated, and then demodulated, integrated, and fed back to the SQUID device to form a SQUID flux lock.
  • the loop thus locks the working point.
  • the magnetic flux modulation signal is a square wave signal with a duty ratio of 50%, and its high level and low power are Conversely, the amplitude of the flat is modulated by the flux modulation signal, and the operating point of the SQUID device jumps between the two operating points, the first operating point W+ and the second operating point W.
  • the measured magnetic flux signal detected by the SQUID device 21 is converted into a corresponding electrical signal, and the preamplifier 22 amplifies the electrical signal.
  • the low frequency noise in the output signal of the preamplifier 22 is then filtered by the high pass filter 23 and the amount of DC is isolated.
  • the signal output from the high pass filter 23 is then demodulated by the demodulator 25.
  • the signal output by the demodulator 25 is then integrated by the integrator 26.
  • the signal is fed back to the SQUID device 21 by the feedback module 27 to form a SQUID flux lock loop to lock the operating point.
  • a small change in the measured magnetic flux signal causes a slight change in the SQUID operating point, as shown in FIG. 4, and when the SQUID operates in two, respectively.
  • different working points first working point W+ and second working point W-
  • the changing trend of the two working points is opposite, such small changes just cancel each other out.
  • the change trend of the first working point W+ is upward
  • the change trend of the second working point W- is downward.
  • the first operating point W+ and the second operating point W- are on the SQUID flux-voltage characteristic curve.
  • the difference is half a cycle; more specifically, in the embodiment, the first operating point W+ and the second operating point W- are located at an intermediate point between the peak and the trough.
  • the direct reading type magnetic flux modulation readout circuit and method of the present invention have the following beneficial effects:
  • SQUID device and readout circuit are directly connected to realize flux modulation, and noise suppression is superior; modulation frequency selection is wider, which is beneficial to signal-to-noise ratio improvement; overcomes the load effect of traditional flux modulation circuit transformer, SQUID flux voltage The curve has no attenuation.
  • a high-pass filter is introduced after the output of the preamplifier to ensure that the output bias voltage and low frequency noise of the preamplifier are isolated while the signal passes.
  • the SQUID device is matched with the preamplifier, which overcomes the bandwidth limitation problem of SQUID and transformer matching in the traditional flux modulation circuit, no loss of higher harmonic components, and less distortion of SQUID flux-voltage curve.
  • the present invention provides a direct reading flux modulation readout circuit comprising: a SQUID device for detecting a measured magnetic flux signal; a preamplifier for amplifying an output signal of the SQUID device; filtering a DC amount and a high-pass filter for low-frequency noise; a modem signal generator for generating a flux modulation signal and a magnetic flux demodulation signal; a demodulator for demodulating an output signal of the high-pass filter according to the magnetic flux demodulation signal;
  • the output signal of the device is integrated to generate an integrator that responds to the voltage signal; and a feedback module that modulates the response voltage signal through the flux modulation signal and feeds back to the SQUID device.
  • the working point of the SQUID device is set to jump between the first working point and the second working point by a magnetic flux modulation signal, and the changing trend of the first working point and the second working point is opposite, and the detected Measuring the magnetic flux signal into a corresponding electrical signal, After the electrical signal is amplified, high-pass filtering is performed to filter out the low-frequency noise, and the DC amount is isolated, and then demodulated, integrated, and fed back to the SQUID device to form a SQUID flux lock loop to lock the operating point.
  • the direct reading flux modulation readout circuit and method of the present invention achieves isolation of the preamplifier low frequency noise and output DC bias by a high pass filter.
  • the direct-reading magnetic flux modulation readout circuit and method of the present invention avoids the use of a transformer compared to the conventional magnetic flux modulation circuit and method, and achieves suppression of low-frequency noise by magnetic flux modulation. Due to the high input impedance of the preamplifier, the SQUID flux-to-voltage conversion factor is not reduced by the load effect; the preamplifier has a wide bandwidth and does not generate high harmonic distortion to the SQUID flux voltage curve; The thermal noise problem of the transformer.
  • the direct-reading magnetic flux modulation readout circuit and method of the present invention completely solves the negative factors introduced by the transformer in the conventional magnetic flux modulation circuit, and the circuit structure is simpler and more practical. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

一种直读式磁通调制读出电路（2），其包括：SQUID器件(21)；对SQUID器件(21)输出信号放大的前置放大器(22)；滤除直流量和低频噪声的高通滤波器(23)；调制解调信号发生器(24)；对高通滤波器(23)的输出信号解调的解调器(25)；积分并产生响应电压信号的积分器(26)；将响应电压信号后反馈至SQUID器件(21)的反馈模块(27)；还提供了一种直读式磁通调制读出方法，其通过调制使SQUID器件(21)的工作点在两个工作点之间跳跃，两个工作点的变化趋势相反，被测信号经过放大、高通滤波、解调、积分后反馈回SQUID器件(21)，以此锁定工作点。该电路（2）通过高通滤波器（23）实现了对前置放大器（22）低频噪声和输出直流偏置的隔离；SQUID磁通-电压转换系数不会因负载效应而降低；不会对SQUID磁通电压曲线产生高次谐波失真；避免了变压器的热噪声问题；电路结构更简单，实用性更强。

Description

一种直读式磁通调制读出电路及方法 技术领域
本发明涉及磁传感器技术领域，特别是涉及一种直读式磁通调制读出电路及方法。
背景技术
超导量子干涉器件(Superconducting Quantum Interference Device，SQUID)是一种灵敏度极高的磁敏感器件，可构建超导磁传感器。广泛应用于生物磁场、地球磁场异常、极低场核磁共振及地球物理勘探等微弱磁场探测应用领域，其探测灵敏度已经达到飞特(10-15特斯拉)量级。SQUID磁传感器是极限探测、科学研究中重要的磁传感器设备，具有很高的科研和应用价值。
实际应用时，SQUID多工作于低频段(小于10Hz)，低频噪声性能是决定应用效果的重要性能指标。前置放大器的低频噪声和SQUID芯片的临界电流涨落等是SQUID磁传感器低频噪声的主要噪声来源，严重制约了SQUID在低频磁测领域的应用(尤其是生物磁探测和地球物理勘探应用)。针对该问题，目前国际上已经有专利针对SQUID磁传感器的低频噪声抑制提出了解决方案：
现有技术中公开了一种基于磁通调制技术降低磁传感器低频噪声的方法，该方法通过在传感器中加入较高频率的调制磁通，将被测低频信号调制到高频处(一般100kHz左右)，从而避开前置放大器的低频噪声段，实现低频噪声抑制；同时，该方法也可以对临界电流涨落引入的同相低频噪声的有效抑制(尤其是对高温SQUID)。为了实现良好的阻抗匹配，以降低前置放大器噪声，这里在SQUID和前置放大器中间引入了变压器。如图1所示为实现该方法的磁通调制电路1，包括SQUID器件11、变压器12、前置放大器13、解调器14、积分器15、调制解调信号发生器16、反馈电阻Rf、反馈线圈Lf以及电阻。SQUID器件11通过电阻与变压器12的原边相连接，变压器12的副边输出接入到前置放大器13，前置放大器13的输出接入解调器14中进行解调，解调后的输出接入积分器15积分后通过反馈电阻Rf和反馈线圈Lf将该磁通反馈回SQUID器件11中，从而保证SQUID磁通工作点不变化，调制磁通的信号由调制解调信号发生器16产生，经过电阻衰减后同样送入反馈线圈Lf，对SQUID的磁通工作点进行调制，同时，调制解调信号发生器16也产生同步的解调信号送入解调器14中。变压器12的引入产生了三个负面影响：(1)SQUID输出电压信号幅度降低(变压器源边负载)；(2)SQUID输出信号的高频谐波成分被滤除，导致工作点处的
Figure PCTCN2016096327-appb-000001
变小；(3)变压器本身存在热噪声，因此，磁通调制读出电路的噪声并不比直读式读出电路好(尤其是 对于大βc的SQUID芯片)，此外，变压器12的引入也导致电路结构更复杂，实用性下降。
发明内容
鉴于以上所述现有技术的缺点，本发明的目的在于提供一种直读式磁通调制读出电路及方法，用于解决现有技术中变压器的引入带来的热噪声、信号幅度降低、工作点处的
Figure PCTCN2016096327-appb-000002
变小等问题。
为实现上述目的及其他相关目的，本发明提供一种直读式磁通调制读出电路，所述直读式磁通调制读出电路至少包括：
SQUID器件，用于检测被测磁通信号并转化为相应的电信号输出；
前置放大器，与所述SQUID器件相连，对所述SQUID器件输出的电信号进行放大；
高通滤波器，与所述前置放大器相连，用于滤除所述前置放大器输出的直流量和低频噪声；
调制解调信号发生器，用于产生磁通调制信号和磁通解调信号；
解调器，与所述高通滤波器及所述调制解调信号发生器相连，根据所述磁通解调信号对所述高通滤波器的输出信号进行解调；
积分器，与所述解调器相连，对所述解调器的输出信号进行积分，并输出与所述被测磁通信号成比例的响应电压信号；
反馈模块，与所述积分器及所述调制解调信号发生器相连，将所述响应电压信号通过所述磁通调制信号调制后反馈至所述SQUID器件，以此锁定工作点。
优选地，所述高通滤波器包括连接于所述前置放大器和所述解调器之间的电容，以及一端连接于所述电容输出端、另一端接地的电阻。
优选地，所述反馈模块包括反馈电阻及反馈线圈；所述反馈电阻的一端连接所述积分器的输出端，另一端连接所述反馈线圈；所述反馈线圈的另一端接地，所述反馈电阻及所述反馈线圈之间连接所述磁通调制信号。
更优选地，所述磁通调制信号为占空比为50％的方波信号。
为实现上述目的及其他相关目的，本发明提供一种上述直读式磁通调制读出电路的读出方法，所述直读式磁通调制读出方法至少包括：
通过磁通调制信号将SQUID器件的工作点设定在第一工作点及第二工作点之间跳跃，所述第一工作点及所述第二工作点的变化趋势相反，将检测到的被测磁通信号转化为相应的电信号，对该电信号放大后进行高通滤波以滤除低频噪声，并隔离直流量，然后经解调、积分 后反馈回所述SQUID器件，形成SQUID磁通锁定环路以此锁定工作点。
优选地，所述第一工作点与所述第二工作点相差半个周期。
如上所述，本发明的直读式磁通调制读出电路及方法，具有以下有益效果：
1、SQUID器件与读出电路直接连接实现了磁通调制，噪声抑制更优越；调制频率选择更宽，有利于信噪比提升；克服了传统磁通调制电路变压器的负载效应，SQUID磁通电压曲线无衰减。
2、在前置放大器输出后引入高通滤波器，保证信号通过的同时，隔离了前置放大器的输出偏置电压和低频噪声。
3、避免了变压器的使用，可选择的磁通调制频率范围更宽，针对低频信号的采集，可以采用更低的调制频率，避免切换暂态效应对磁通调制的影响；避免变压器存在的热噪声问题。
4、SQUID器件与前置放大器匹配，克服了传统磁通调制电路中SQUID与变压器匹配存在的带宽限制问题，高次谐波分量无损失，SQUID磁通-电压曲线失真更小。
附图说明
图1显示为现有技术中的磁通调制电路的结构示意图。
图2显示为本发明的直读式磁通调制读出电路的结构示意图。
图3显示为典型SQUID磁通-电压传输特性曲线示意图。
图4显示为本发明的直读式磁通调制读出方法的原理示意图。
元件标号说明
1     磁通调制电路
11    SQUID器件
12    变压器
13    前置放大器
14    解调器
15    积分器
16    调制解调信号发生器
2     直读式磁通调制读出电路
21    SQUID器件
22    前置放大器
23    高通滤波器
24    调制解调信号发生器
25    解调器
26    积分器
27    反馈模块
具体实施方式
以下通过特定的具体实例说明本发明的实施方式，本领域技术人员可由本说明书所揭露的内容轻易地了解本发明的其他优点与功效。本发明还可以通过另外不同的具体实施方式加以实施或应用，本说明书中的各项细节也可以基于不同观点与应用，在没有背离本发明的精神下进行各种修饰或改变。
请参阅图2～图4。需要说明的是，本实施例中所提供的图示仅以示意方式说明本发明的基本构想，遂图式中仅显示与本发明中有关的组件而非按照实际实施时的组件数目、形状及尺寸绘制，其实际实施时各组件的型态、数量及比例可为一种随意的改变，且其组件布局型态也可能更为复杂。
如图2所示，本发明提供一种直读式磁通调制读出电路2，所述直读式磁通调制读出电路2至少包括：
SQUID器件21、前置放大器22、高通滤波器23、调制解调信号发生器24、解调器25、积分器26、反馈模块27。
如图2所示，所述SQUID器件用于检测被测磁通信号并转化为相应的电信号输出。
具体地，所述SQUID器件由两个超导约瑟夫森结并联构成的一个超导环，在约瑟夫森结的两端引出端子，加载一定的偏置电流，SQUID器件两端的电压将具有随其感应磁场发生变化的特性，典型的SQUID磁通-电压传输特性曲线如图3所示。所述SQUID器件的一端接地，另一端连接所述前置放大器22的输入端，将检测到的被测磁通信号转化为相应的电信号后输出到所述前置放大器22。
如图2所示，所述前置放大器22与所述SQUID器件相连，对所述SQUID器件21输出的电信号进行放大。
具体地，所述前置放大器22为高输入阻抗，SQUID磁通-电压转换系数不会因负载效应而降低，同时所述前置放大器22的带宽较宽，不会对SQUID磁通-电压曲线产生高次谐波失真。
如图2所示，所述高通滤波器23与所述前置放大器22相连，用于滤除所述前置放大器22输出的直流量和低频噪声。
具体地，所述高通滤波器23的具体结构不限，任意能实现高通滤波功能的电路结构均包括在内。在本实施例中，所述高通滤波器23包括电容C和第一电阻R1，所述电容C连接于所述前置放大器22的输出端和所述解调器25的输入端之间；所述第一电阻R1的一端连接于所述电容C和所述解调器25之间、另一端接地。
如图2所示，所述调制解调信号发生器24用于产生磁通调制信号和磁通解调信号。
具体地，所述调制解调信号发生器24分别产生磁通调制信号及与之所述磁通调制信号向对应的磁通解调信号。在本实施例中，所述磁通调制信号为占空比为50％的方波信号，以此使工作点在第一工作点及第二工作点之间跳变，其中第一工作点及第二工作点的变化趋势相反。
如图2所示，所述解调器25与所述高通滤波器23及所述调制解调信号发生器24相连，根据所述磁通解调信号24对所述高通滤波器23的输出信号进行解调。
如图2所示，所述积分器26与所述解调器25相连，对所述解调器25的输出信号进行积分，并输出与所述被测磁通信号成比例的响应电压信号Vf。
如图2所示，所述反馈模块27与所述积分器26及所述调制解调信号发生器24相连，将所述响应电压信号Vf通过所述磁通调制信号调制后反馈至所述SQUID器件21，以此锁定工作点。
具体地，所述反馈模块27包括反馈电阻Rf及反馈线圈Lf，所述反馈电阻Rf的一端连接所述积分器26的输出端，另一端连接所述反馈线圈Lf，所述反馈线圈Lf的另一端接地，所述反馈电阻Rf及所述反馈线圈Lf之间连接所述磁通调制信号。所述响应电压信号Vf及所述磁通调制信号分别通过所述反馈电阻Rf及第二电阻R2产生反馈电流，反馈电流通过所述反馈线圈Lf与所述SQUID器件21产生互感Mf，所述互感Mf抵消所述被测磁通信号，使得整个负反馈回路稳定，工作点被锁定。
如图2～图4所示，上述直读式磁通调制读出电路2的工作原理如下：
通过磁通调制信号将SQUID器件的工作点设定在第一工作点及第二工作点之间跳跃，所述第一工作点及所述第二工作点的变化趋势相反，将检测到的被测磁通信号转化为相应的电信号，对该电信号放大后进行高通滤波以滤除低频噪声，并隔离直流量，然后经解调、积分后反馈回所述SQUID器件，形成SQUID磁通锁定环路以此锁定工作点。
具体地，如图4所示，所述磁通调制信号为占空比为50％的方波信号，其高电平与低电 平的幅值相反，受所述磁通调制信号的调制，所述SQUID器件的工作点在第一工作点W+及第二工作点W-这两个工作点之间跳跃。将SQUID器件21检测到的被测磁通信号转化为相应的电信号，所述前置放大器22对该电信号放大。然后通过所述高通滤波器23将所述前置放大器22输出信号中的低频噪声滤除，并隔离直流量。然后经所述解调器25对所述高通滤波器23输出的信号进行解调。再藉由所述积分器26对所述解调器25输出的信号进行积分。通过反馈模块27将信号反馈回所述SQUID器件21，形成SQUID磁通锁定环路以此锁定工作点。当所述直读式磁通调制读出电路2处于锁定状态下时，被测磁通信号的微小变化会导致SQUID工作点发生微小的变动，图4所示，而当SQUID分别工作于两个不同的工作点(第一工作点W+及第二工作点W-)时，且这两个工作点的变化趋势相反时，这种微小的变动正好相互抵消。在本实施例中，所述第一工作点W+的变化趋势向上，所述第二工作点W-的变化趋势向下。为了确保所述第一工作点W+及所述所述第二工作点W-变化的斜率相同，所述第一工作点W+与所述第二工作点W-在SQUID磁通-电压特性曲线上相差半个周期；更具体地，在本实施例中，所述第一工作点W+及所述第二工作点W-位于波峰和波谷的中间点。
如上所述，本发明的直读式磁通调制读出电路及方法，具有以下有益效果：
1、SQUID器件与读出电路直接连接实现了磁通调制，噪声抑制更优越；调制频率选择更宽，有利于信噪比提升；克服了传统磁通调制电路变压器的负载效应，SQUID磁通电压曲线无衰减。
2、在前置放大器输出后引入高通滤波器，保证信号通过的同时，隔离了前置放大器的输出偏置电压和低频噪声。
3、避免了变压器的使用，可选择的磁通调制频率范围更宽，针对低频信号的采集，可以采用更低的调制频率，避免切换暂态效应对磁通调制的影响；避免变压器存在的热噪声问题。
4、SQUID器件与前置放大器匹配，克服了传统磁通调制电路中SQUID与变压器匹配存在的带宽限制问题，高次谐波分量无损失，SQUID磁通-电压曲线失真更小。
综上所述，本发明提供一种直读式磁通调制读出电路，包括：检测被测磁通信号的SQUID器件；对SQUID器件的输出信号进行放大的前置放大器；滤除直流量和低频噪声的高通滤波器；产生磁通调制信号和磁通解调信号的调制解调信号发生器；根据磁通解调信号对高通滤波器的输出信号进行解调的解调器；对解调器的输出信号进行积分，产生响应电压信号的积分器；以及将响应电压信号通过磁通调制信号调制后反馈至SQUID器件的反馈模块。通过磁通调制信号将SQUID器件的工作点设定在第一工作点及第二工作点之间跳跃，所述第一工作点及所述第二工作点的变化趋势相反，将检测到的被测磁通信号转化为相应的电信号，对该 电信号放大后进行高通滤波以滤除低频噪声，并隔离直流量，然后经解调、积分后反馈回所述SQUID器件，形成SQUID磁通锁定环路以此锁定工作点。本发明的直读式磁通调制读出电路及方法通过高通滤波器实现了对前置放大器低频噪声和输出直流偏置的隔离。并且通过调整器件参数，可以实现SQUID和前置放大器的噪声和阻抗的良好匹配。本发明的直读式磁通调制读出电路及方法相较于传统磁通调制电路及方法避开了变压器的使用，实现磁通调制对低频噪声的抑制。由于前置放大器为高输入阻抗，SQUID磁通-电压转换系数不会因负载效应而降低；前置放大器带宽较宽，不会对SQUID磁通电压曲线产生高次谐波失真；同时也避免了变压器的热噪声问题。总体而言，本发明的直读式磁通调制读出电路及方法完全解决了传统磁通调制电路中变压器引入的负面因素，同时电路结构更简单，实用性更强。所以，本发明有效克服了现有技术中的种种缺点而具高度产业利用价值。
上述实施例仅例示性说明本发明的原理及其功效，而非用于限制本发明。任何熟悉此技术的人士皆可在不违背本发明的精神及范畴下，对上述实施例进行修饰或改变。因此，举凡所属技术领域中具有通常知识者在未脱离本发明所揭示的精神与技术思想下所完成的一切等效修饰或改变，仍应由本发明的权利要求所涵盖。

Claims (6)

  1. 一种直读式磁通调制读出电路，其特征在于，所述直读式磁通调制读出电路至少包括：
    SQUID器件，用于检测被测磁通信号并转化为相应的电信号输出；
    前置放大器，与所述SQUID器件相连，对所述SQUID器件输出的电信号进行放大；
    高通滤波器，与所述前置放大器相连，用于滤除所述前置放大器输出的直流量和低频噪声；
    调制解调信号发生器，用于产生磁通调制信号和磁通解调信号；
    解调器，与所述高通滤波器及所述调制解调信号发生器相连，根据所述磁通解调信号对所述高通滤波器的输出信号进行解调；
    积分器，与所述解调器相连，对所述解调器的输出信号进行积分，并输出与所述被测磁通信号成比例的响应电压信号；
    反馈模块，与所述积分器及所述调制解调信号发生器相连，将所述响应电压信号通过所述磁通调制信号调制后反馈至所述SQUID器件，以此锁定工作点。
  2. 根据权利要求1所述的直读式磁通调制读出电路，其特征在于：所述高通滤波器包括连接于所述前置放大器和所述解调器之间的电容，以及一端连接于所述电容输出端、另一端接地的电阻。
  3. 根据权利要求1所述的直读式磁通调制读出电路，其特征在于：所述反馈模块包括反馈电阻及反馈线圈；所述反馈电阻的一端连接所述积分器的输出端，另一端连接所述反馈线圈；所述反馈线圈的另一端接地，所述反馈电阻及所述反馈线圈之间连接所述磁通调制信号。
  4. 根据权利要求1或3所述的直读式磁通调制读出电路，其特征在于：所述磁通调制信号为占空比为50％的方波信号。
  5. 一种如权利要求1～4任意一项所述的直读式磁通调制读出电路的读出方法，其特征在于：所述直读式磁通调制读出方法至少包括：
    通过磁通调制信号将SQUID器件的工作点设定在第一工作点及第二工作点之间跳跃，所述第一工作点及所述第二工作点的变化趋势相反，将检测到的被测磁通信号转化为相应的电信号，对该电信号放大后进行高通滤波以滤除低频噪声，并隔离直流量，然后经解调、积分后反馈回所述SQUID器件，形成SQUID磁通锁定环路以此锁定工作点。
  6. 根据权利要求5所述的直读式磁通调制读出方法，其特征在于：所述第一工作点与所述第二工作点相差半个周期。
PCT/CN2016/096327 2016-01-29 2016-08-23 一种直读式磁通调制读出电路及方法 WO2017128706A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201610066331.4A CN105676152A (zh) 2016-01-29 2016-01-29 一种直读式磁通调制读出电路及方法
CN201610066331.4 2016-01-29

Publications (1)

Publication Number Publication Date
WO2017128706A1 true WO2017128706A1 (zh) 2017-08-03

Family

ID=56303093

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2016/096327 WO2017128706A1 (zh) 2016-01-29 2016-08-23 一种直读式磁通调制读出电路及方法

Country Status (2)

Country Link
CN (1) CN105676152A (zh)
WO (1) WO2017128706A1 (zh)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105676152A (zh) * 2016-01-29 2016-06-15 中国科学院上海微***与信息技术研究所 一种直读式磁通调制读出电路及方法
CN110632423B (zh) * 2019-09-26 2021-05-11 中国科学院上海微***与信息技术研究所 一种低温物性测试***及装置
CN111208452A (zh) * 2019-11-07 2020-05-29 中国计量大学 一种用于多铁性磁传感器的直读式读出***
CN111398880A (zh) * 2019-11-22 2020-07-10 中国计量大学上虞高等研究院有限公司 一种用于多铁性磁传感器的负反馈式读出***
CN111413652A (zh) * 2019-11-22 2020-07-14 中国计量大学上虞高等研究院有限公司 一种基于负反馈结构的宽工作区间多铁性磁传感器

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0499980A (ja) * 1990-08-18 1992-03-31 Mitsubishi Electric Corp 超伝導磁力計
JPH04268471A (ja) * 1991-02-22 1992-09-24 Seiko Instr Inc 高感度磁場検出装置
US6448767B1 (en) * 2000-06-16 2002-09-10 Honeywell International, Inc. Fast flux locked loop
US20030016010A1 (en) * 2001-07-19 2003-01-23 Hitachi, Ltd. Apparatus for measuring a magnetic field
JP2004157092A (ja) * 2002-11-08 2004-06-03 Japan Science & Technology Agency Ｓｑｕｉｄの温度制御装置および方法
CN102353911A (zh) * 2011-08-31 2012-02-15 中国科学院上海微***与信息技术研究所 基于扰动补偿的环境场下高灵敏度磁测量装置及实现方法
CN102426343A (zh) * 2011-08-31 2012-04-25 中国科学院上海微***与信息技术研究所 基于squid偏置电压反转的读出电路及低频噪声的抑制方法
CN103389478A (zh) * 2012-10-31 2013-11-13 中国科学院上海微***与信息技术研究所 一种基于超导磁传感器的数字化实时磁场补偿装置及方法
CN105676152A (zh) * 2016-01-29 2016-06-15 中国科学院上海微***与信息技术研究所 一种直读式磁通调制读出电路及方法

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0499980A (ja) * 1990-08-18 1992-03-31 Mitsubishi Electric Corp 超伝導磁力計
JPH04268471A (ja) * 1991-02-22 1992-09-24 Seiko Instr Inc 高感度磁場検出装置
US6448767B1 (en) * 2000-06-16 2002-09-10 Honeywell International, Inc. Fast flux locked loop
US20030016010A1 (en) * 2001-07-19 2003-01-23 Hitachi, Ltd. Apparatus for measuring a magnetic field
JP2004157092A (ja) * 2002-11-08 2004-06-03 Japan Science & Technology Agency Ｓｑｕｉｄの温度制御装置および方法
CN102353911A (zh) * 2011-08-31 2012-02-15 中国科学院上海微***与信息技术研究所 基于扰动补偿的环境场下高灵敏度磁测量装置及实现方法
CN102426343A (zh) * 2011-08-31 2012-04-25 中国科学院上海微***与信息技术研究所 基于squid偏置电压反转的读出电路及低频噪声的抑制方法
CN103389478A (zh) * 2012-10-31 2013-11-13 中国科学院上海微***与信息技术研究所 一种基于超导磁传感器的数字化实时磁场补偿装置及方法
CN105676152A (zh) * 2016-01-29 2016-06-15 中国科学院上海微***与信息技术研究所 一种直读式磁通调制读出电路及方法

Also Published As

Publication number Publication date
CN105676152A (zh) 2016-06-15

Similar Documents

Publication Publication Date Title
WO2017128706A1 (zh) 一种直读式磁通调制读出电路及方法
CN203629593U (zh) 用于光纤传感微弱信号的检测电路
CN102426343B (zh) 基于squid偏置电压反转的读出电路及低频噪声的抑制方法
Xie et al. A voltage biased superconducting quantum interference device bootstrap circuit
EP2780732B1 (en) Dc squid based rf magnetometer operating at a bandwidth of 200 mhz and higher and method of operating
CN202614920U (zh) 一种基于巨磁阻抗相位响应的磁传感器
CN106199465B (zh) 一种双级超导量子干涉器放大装置、方法及squid磁传感器
CN111413654A (zh) 一种降低隧道磁电阻传感器噪声的***及方法
CN108693486A (zh) 一种基于amr传感器的微弱低频磁信号检测方法和***
CN109870664A (zh) 一种磁场测量***及测量方法
CN104950275B (zh) 超导量子干涉器磁传感器的性能测试装置及方法
CN110672916A (zh) 一种开启式数字化直流电流测量装置
JP2002148322A (ja) 超伝導量子干渉素子を用いた信号検出器およびその測定方法
US9453891B2 (en) Magnetic field detection device
Caputo et al. Superconducting quantum interference filters as absolute magnetic field sensors
Reich et al. Experimental study of a hybrid single flux quantum digital superconducting quantum interference device magnetometer
CN104569867B (zh) 超导量子干涉传感组件及所适用的超导量子干涉传感器
CN114675064A (zh) 一种高精度双量程磁通门电流传感器
CN209803221U (zh) 一种电流采样电路结构及装置
Zhang et al. A SQUID gradiometer module with wire-wound pickup antenna and integrated voltage feedback circuit
Hong et al. Flux modulation scheme for direct current SQUID readout revisited
JP2537129B2 (ja) 狭帯域ｆｌｌ回路
RU2539726C1 (ru) Феррозондовый магнитометр и способ измерения компонент индукции магнитного поля при помощи векторной компенсации
Thomasson et al. High slew rate large bandwidth integrated dc SQUID magnetometer for NMR applications
CN109407156B (zh) 全频段磁传感器

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 16887583

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 16887583

Country of ref document: EP

Kind code of ref document: A1