A direct coupled dc squid readout electronics

Abstract

The present application relates to a kind of direct coupling DC SQUID readout electronics, including gradiometer antenna and SQUID sensor, the gradiometer antenna is superconducting contact with the input coil of SQUID sensor, and form superconducting flux transformer with it, the output of the SQUID sensor is connected with the input of conversion amplifier, the output of the conversion amplifier is connected with the input of integrator, the SQUID sensor is connected with the output of bias voltage module, the output of the integrator is analog output terminal, the output of the integrator is connected with the input of feedback gain module, the output of the feedback gain module is connected with feedback coil, the feedback coil is connected with SQUID sensor inductance.The present application makes output voltage more linear.

Description

Technical Field

[0001] This invention relates to the field of SQUID detection, and more particularly to a direct-coupled DC SQUID readout electronic device. Background Technology

[0002] Magnetic sensors based on superconducting quantum interference devices (SQUIDs) are currently the most sensitive magnetic sensors known. Low-temperature superconducting SQUIDs have a sensitivity better than 10 femtoseconds, while high-temperature superconducting SQUIDs have a sensitivity better than 100 femtoseconds. SQUID magnetic sensors are important high-end application sensors, widely used in fields such as biomagnetism, geophysical exploration, and extremely low-field nuclear magnetic resonance (NMR) for detecting weak magnetic fields, possessing high scientific research and application value. The magnetic flux quantum is a physical constant: Фo = 2.07 x 10⁻⁶. -15 Wb. Since Фο is a very small value, this determines the SQUID's high sensitivity to magnetic flux, and thus its high sensitivity to magnetic fields. The relationship between magnetic flux and magnetic field (B) is determined by a simple formula: Ф=B×S, where S is the area through which the magnetic flux penetrates. The SQUID's critical current depends on the magnetic flux. If a bias current passes through the SQUID and exceeds the critical current, a voltage appears on the SQUID, the value of which depends on the magnetic flux within the SQUID. ΔV is the maximum change in voltage across the SQUID under the influence of magnetic flux. The voltage on the SQUID exhibits a periodic dependence on changes in magnetic flux. δV is called the SQUID modulation depth (or voltage oscillation). This dependence is used to construct the readout electron in magnetic field measurements. Due to the small aperture area (ring area) of the SQUID, Ф=B×S, a large magnetic field is required to generate the desired magnetic flux within the small area of ​​the SQUID, necessitating a circuit that is resistant to interference and has a stable output. Summary of the Invention

[0003] To address the aforementioned technical problems, the purpose of this invention is to provide a directly coupled DC SQUID readout electronic device.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A direct-coupled DC SQUID readout electronics includes a gradient meter antenna and a SQUID sensor. The gradient meter antenna is in superconducting contact with the input coil of the SQUID sensor, forming a superconducting flux converter. The output of the SQUID sensor is connected to the input of a conversion amplifier, the output of the conversion amplifier is connected to the input of an integrator, the SQUID sensor is connected to the output of a bias voltage module, the output of the integrator is an analog output, the output of the integrator is connected to the input of a feedback gain module, the output of the feedback gain module is connected to a feedback coil, and the feedback coil is inductively connected to the SQUID sensor.

[0006] Preferably, in the direct-coupled DC SQUID readout electronic device, the conversion amplifier includes three identical and independent switching modules.

[0007] The switching module consists of switch Q5 and switch Q8. The first pin of switch Q5 is connected to the eighth pin of switch Q8, and the eighth pin of switch Q5 is connected to the first pin of switch Q8. The first pin of switch Q5 is connected to the positive output, and the eighth pin of switch Q5 is connected to the negative output. The second pin of switch Q5 and the seventh pin of switch Q8 are connected to the third pin of the QUID sensor, and the seventh pin of switch Q5 and the second pin of switch Q8 are connected to the first pin of the QUID sensor. The third and sixth pins of switches Q5 and Q8 are grounded through series resistors R16 and R11, Zener diode IC5, and Zener diode IC6.

[0008] Preferably, in the direct-coupled DC SQUID readout electronic device, the switch Q5 is model MAT01.

[0009] Preferably, in the direct-coupled DC SQUID readout electronic device, the bias voltage module includes chips IC7, IC8, and IC12A. The second pin of chip IC8 is connected to +5V, the fourth pin of chip IC8 is grounded, the sixth pin of chip IC8 is connected to the fourth pin of chip IC8 through capacitor C16, the sixth pin of chip IC8 is connected to the first pin of chip IC7, and the sixth pin of chip IC8 is connected to the bias compensation terminal through series resistors R66 and R68. The second pin of chip IC7 is connected to the DATA_BIAS_IN terminal, and the third pin of chip IC7... The pin is connected to the SCLK terminal. The fourth pin of chip IC7 is connected to the DIN terminal. The fifth pin of chip IC7 is connected to the V+ terminal. The sixth pin of chip IC7 is connected to the first pin of chip IC12A. The seventh pin of chip IC7 is connected to +5V and also to the sixth pin of chip IC12A. The seventh pin of chip IC7 is grounded through capacitor C17. The eighth pin of chip IC7 is grounded. The eighth pin of chip IC12A is connected to resistor R66. The second pin of chip IC12A is connected to the V- terminal and also to grounded through capacitor C23. The seventh pin of chip IC12A is connected to the bias compensation terminal.

[0010] Preferably, the direct-coupled DC SQUID readout electronic device is characterized in that: the model of chip IC7 is MAX531, the model of chip IC8 is MAX621, and the model of chip IC12A is AD823.

[0011] Preferably, in the direct-coupled DC SQUID readout electronic device, the feedback gain module includes chip IC1A and chip IC1B. The sixth pin of chip IC1B is connected to voltage divider resistors R50 and R51 through resistor R49. Resistor R50 is connected to the output terminal of integrator (4). Resistor R51 is grounded. The sixth pin of chip IC1B is connected to the first pin of the feedback coil through series resistors R42 and R44. The seventh pin of chip IC1B is connected to resistor R44. The third pin of chip IC1A is connected to resistor R49. The second pin of chip IC1A is connected to the first pin of chip IC1A through resistor R43. The first pin of chip IC1A is connected to the third pin of the feedback coil through resistor R45. The eighth pin of chip IC1A is connected to the VCC terminal. The fourth pin of chip IC1A is grounded through capacitor C11.

[0012] Preferably, in the direct-coupled DC SQUID readout electronic device, both chip IC1A and chip IC1B are of model OPA2810.

[0013] By means of the above-described solution, the present invention has at least the following advantages:

[0014] The SQUID sensor of this invention, through a bias voltage module, a conversion amplifier, an integrator, and a feedback gain module, can greatly reduce magnetic flux interference and coupling between channels, solve the problem of signal crosstalk between multiple channels, and make the output voltage more linear.

[0015] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a system block diagram of the present invention;

[0018] Figure 2 This is a circuit diagram of the conversion amplifier of the present invention;

[0019] Figure 3 This is a circuit diagram of the bias voltage module of the present invention;

[0020] Figure 4 This is a circuit diagram of the feedback gain module of the present invention;

[0021] Figure 5 This is the signal diagram of the present invention before processing;

[0022] Figure 6 This is the signal diagram after bias correction according to the present invention;

[0023] Figure 7 This is the signal diagram after amplification according to the present invention;

[0024] Figure 8 This is the signal diagram obtained after integration and feedback compensation according to the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0027] Example

[0028] like Figures 1 to 8 As shown, a direct-coupled DC SQUID readout electronics includes a gradient meter antenna 1 and a SQUID sensor 2. The gradient meter antenna 1 is in superconducting contact with the input coil of the SQUID sensor 2, forming a superconducting flux converter. The output terminal of the SQUID sensor 2 is connected to the input terminal of a conversion amplifier 3. The output terminal of the conversion amplifier 3 is connected to the input of an integrator 4. The SQUID sensor 2 is connected to the output terminal of a bias voltage module 5. The output terminal of the integrator 4 is an analog output terminal. The output terminal of the integrator 4 is connected to the input terminal of a feedback gain module 6. The output terminal of the feedback gain module 6 is connected to a feedback coil 7. The feedback coil 7 is inductively connected to the SQUID sensor 2.

[0029] like Figure 2 As shown, the conversion amplifier 3 includes three identical and independent switching modules.

[0030] The switching module consists of switch Q5 and switch Q8. The first pin of switch Q5 is connected to the eighth pin of switch Q8, and the eighth pin of switch Q5 is connected to the first pin of switch Q8. The first pin of switch Q5 is connected to the positive output, and the eighth pin of switch Q5 is connected to the negative output. The second pin of switch Q5 and the seventh pin of switch Q8 are connected to the third pin of QUID sensor 2, and the seventh pin of switch Q5 and the second pin of switch Q8 are connected to the first pin of QUID sensor 2. The third and sixth pins of switches Q5 and Q8 are grounded through series resistors R16 and R11, Zener diode IC5, and Zener diode IC6.

[0031] The model number of the switch Q5 is MAT01.

[0032] like Figure 3As shown, the bias voltage module 5 includes chip IC7, chip IC8, and chip IC12A. The second pin of chip IC8 is connected to +5V, the fourth pin of chip IC8 is grounded, the sixth pin of chip IC8 is connected to the fourth pin of chip IC8 through capacitor C16, the sixth pin of chip IC8 is connected to the first pin of chip IC7, and the sixth pin of chip IC8 is connected to the bias compensation terminal through series resistors R66 and R68. The second pin of chip IC7 is connected to the DATA_BIAS_IN terminal, and the third pin of chip IC7 is connected to the SCLK terminal. The fourth pin of IC7 is connected to the DIN terminal, the fifth pin of IC7 is connected to the V+ terminal, the sixth pin of IC7 is connected to the first pin of IC12A, the seventh pin of IC7 is connected to +5V and also to the sixth pin of IC12A, the seventh pin of IC7 is grounded through capacitor C17, the eighth pin of IC7 is grounded, the eighth pin of IC12A is connected to resistor R66, the second pin of IC12A is connected to the V- terminal and also to ground through capacitor C23, and the seventh pin of IC12A is connected to the bias compensation terminal.

[0033] Among them, the model number of chip IC7 is MAX531, the model number of chip IC8 is MAX621, and the model number of chip IC12A is AD823.

[0034] like Figure 4 As shown, the feedback gain module 6 includes chip IC1A and chip IC1B. The sixth pin of chip IC1B is connected to voltage divider resistors R50 and R51 through resistor R49. Resistor R50 is connected to the output terminal of integrator 4, and resistor R51 is grounded. The sixth pin of chip IC1B is connected to the first pin of the feedback coil through resistors R42 and R44 in series. The seventh pin of chip IC1B is connected to resistor R44. The third pin of chip IC1A is connected to resistor R49. The second pin of chip IC1A is connected to the first pin of chip IC1A through resistor R43. The first pin of chip IC1A is connected to the third pin of the feedback coil through resistor R45. The eighth pin of chip IC1A is connected to the VCC terminal. The fourth pin of chip IC1A is grounded through capacitor C11.

[0035] Both IC1A and IC1B are of model number OPA2810.

[0036] The working principle of this invention is as follows:

[0037] In actual operation, the bias voltage module uses a SQUID sensor. The voltage drop across the SQUID sensor is amplified by a conversion amplifier and then generates a current in the feedback coil through an integrator and a feedback gain module to cooperate with the SQUID sensor, making the output voltage more linear.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] In the description of this application, it should be noted that the terms "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or vertical, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0041] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A direct-coupled DC SQUID readout electronics, comprising a gradiometer antenna (1) and a SQUID sensor (2), wherein the gradiometer antenna (1) is in superconducting contact with the input coil of the SQUID sensor (2) and forms a superconducting flux converter therewith, characterized in that: The output terminal of the SQUID sensor (2) is connected to the input terminal of the conversion amplifier (3), the output terminal of the conversion amplifier (3) is connected to the input of the integrator (4), the SQUID sensor (2) is connected to the output terminal of the bias voltage module (5), the output terminal of the integrator (4) is an analog output terminal, the output terminal of the integrator (4) is connected to the input terminal of the feedback gain module (6), the output terminal of the feedback gain module (6) is connected to the feedback coil (7), and the feedback coil (7) is mutually inductively connected to the SQUID sensor (2). The bias voltage module (5) includes chip IC7, chip IC8, and chip IC12A. The second pin of chip IC8 is connected to +5V, the fourth pin of chip IC8 is grounded, the sixth pin of chip IC8 is connected to the fourth pin of chip IC8 through capacitor C16, the sixth pin of chip IC8 is connected to the first pin of chip IC7, the sixth pin of chip IC8 is connected to the bias compensation terminal through series resistors R66 and R68, the second pin of chip IC7 is connected to the DATA_BIAS_IN terminal, the third pin of chip IC7 is connected to the SCLK terminal, the fourth pin of chip IC7 is connected to the DIN terminal, and the fifth pin of chip IC7 is connected to V+. The terminals are connected as follows: pin 6 of chip IC7 is connected to pin 1 of chip IC12A; pin 7 of chip IC7 is connected to +5V and also to pin 6 of chip IC12A; pin 7 of chip IC7 is grounded through capacitor C17; pin 8 of chip IC7 is grounded; pin 8 of chip IC12A is connected between resistors R66 and R68; pin 2 of chip IC12A is connected to the V- terminal and also grounded through capacitor C23; pin 7 of chip IC12A is connected to the bias compensation terminal; the model of chip IC7 is MAX531, the model of chip IC8 is MAX621, and the model of chip IC12A is AD823. The feedback gain module (6) includes chip IC1A and chip IC1B. The sixth pin of chip IC1B is connected to voltage divider resistors R50 and R51 through resistor R49. Resistor R50 is connected to the output terminal of integrator (4). Resistor R51 is grounded. The sixth pin of chip IC1B is connected to the first pin of feedback coil through series resistors R42 and R44. The seventh pin of chip IC1B is connected between resistors R44 and R42. The third pin of chip IC1A is connected between resistors R49 and R50. The second pin of chip IC1A is connected to the first pin of chip IC1A through resistor R43. The first pin of chip IC1A is connected to the third pin of feedback coil through resistor R45. The eighth pin of chip IC1A is connected to the VCC terminal. The fourth pin of chip IC1A is grounded through capacitor C11. The model of chip IC1A and chip IC1B is OPA2810.

2. The direct-coupled DC SQUID readout electronic device according to claim 1, characterized in that: The conversion amplifier (3) includes three identical and independent switching modules. The switch module consists of switch Q5 and switch Q8. The first pin of switch Q5 is connected to the eighth pin of switch Q8, and the eighth pin of switch Q5 is connected to the first pin of switch Q8. The first pin of switch Q5 is connected to the positive output, and the eighth pin of switch Q5 is connected to the negative output. The second pin of switch Q5 and the seventh pin of switch Q8 are connected to the third pin of QUID sensor (2), and the seventh pin of switch Q5 and the second pin of switch Q8 are connected to the first pin of QUID sensor (2). The third and sixth pins of switches Q5 and Q8 are grounded through series resistors R16 and R11, Zener diode IC5 and Zener diode IC6.

3. A direct-coupled DC SQUID readout electronic device according to claim 2, characterized in that: The model number of the switch Q5 is MAT01.

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