TMR magnetic field sensor

Abstract

The TMR magnetic field sensor comprises a TMR unit connected to form a full-bridge circuit, wherein each bridge arm of the full-bridge circuit is provided with a TMR unit, the TMR units on adjacent bridge arms are sensitive to external magnetic fields in opposite directions, and the TMR units on opposite bridge arms are sensitive to external magnetic fields in the same direction, one of two power supply terminals is connected to a power supply, and the other is connected to ground; and at least one negative capacitance circuit, the negative capacitance circuit is connected in parallel with the TMR unit on a certain bridge arm, one end of the negative capacitance circuit is connected to a grounded power supply terminal, and the other end is connected to an output terminal, and the equivalent capacitance at both ends of the negative capacitance circuit is opposite in sign to the parasitic capacitance of the TMR unit connected in parallel therewith. The present invention sets a negative capacitance circuit in parallel with the TMR unit in the TMR magnetic field sensor, and compensates the parasitic capacitance of the push-pull full-bridge circuit by the negative capacitance circuit, thereby compensating the parasitic capacitance of the push-pull full-bridge circuit, and realizing the expansion of the measurement frequency range of the TMR magnetic field sensor.

Description

Technical Field

[0001] The invention belongs to the field of sensor measurement technology, and in particular relates to a TMR magnetic field sensor. Background Art

[0002] TMR element is a new type of magnetoresistance effect sensor. Compared with AMR element and GMR element, it has the advantages of greater resistance change rate, better temperature characteristics and linearity, and has been widely used in industrial environments. The output sensitivity of TMR magnetic field sensor is limited by its own measurement frequency range. When the measurement frequency range is within the operating frequency range of TMR magnetic field sensor, the output sensitivity attenuation of TMR magnetic field sensor can be below -3dB, and the changing magnetic field signal can be restored well. When the measurement frequency range exceeds the operating frequency range of TMR magnetic field sensor, the output sensitivity attenuation of TMR magnetic field sensor will exceed -3dB, resulting in distortion of the measured changing magnetic field signal. The measurable magnetic field frequency range and sensitivity of TMR magnetic field sensor are mainly affected by factors such as parasitic capacitance of TMR magnetic sensor chip, resistance value of TMR element, and circuit structure of sensor. In order to improve the magnetic field measurement range of TMR magnetic field sensor, people have proposed a variety of methods such as optimizing chip layout, reducing resistance value of TMR element, and changing circuit structure of TMR sensor, but these methods still have limitations in application.

[0003] By optimizing the chip layout and reducing the parasitic capacitance between the circuits and components, the operating frequency range of the TMR magnetic field sensor can be extended, thereby broadening the magnetic field measurement frequency range of the TMR magnetic field sensor. However, the chip layout size of the TMR magnetic sensor is already at the micron level, and the effect of reducing parasitic capacitance by optimizing the layout is limited, and the improvement of the measurement frequency of the TMR magnetic field sensor is also limited.

[0004] The main method of expanding the measurement magnetic field frequency range of the TMR magnetic field sensor by reducing the resistance value of the TMR unit is to adjust the material formula of the TMR unit and obtain TMR units with different resistance values ​​by obtaining materials with different RA values. The RA value refers to the resistance * area value of the TMR unit material. When the material formula remains unchanged, the RA value is a fixed value. The smaller the RA value of the material, the smaller the resistance value can be obtained when the thickness remains unchanged. The TMR material formula has another measurement indicator - the TMR value. The TMR value refers to the ratio of the change in the TMR resistance value in the magnetic field to the minimum resistance value, that is, (maximum resistance value - minimum resistance value) / minimum resistance value. It is usually hoped to obtain a higher TMR value. When the other structures of the sensor remain unchanged, the smaller the resistance value of the TMR unit, the larger the operating frequency range of the TMR magnetic field sensor formed by it. However, due to the need to change the material formula of the TMR unit, there may be a risk of incompatibility between the RA value and the TMR value of the material. The selected formula must meet both a higher TMR value and a smaller RA value, which will increase the R&D cost. On the other hand, reducing the resistance value of the TMR element requires reducing the external operating voltage of the TMR magnetic sensor to avoid excessive operating current. However, reducing the operating voltage of the TMR magnetic sensor will cause the output signal amplitude of the TMR magnetic sensor to decrease, which is not conducive to the application of the TMR magnetic field sensor.

[0005] Changing the circuit structure of the sensor can also broaden the frequency range of the magnetic field measurement of the TMR magnetic field sensor, such as connecting the TMR unit into a single bridge circuit. The single bridge circuit is simpler than the full bridge circuit structure, so it also has less parasitic capacitance than the full bridge circuit. The smaller the parasitic capacitance, the larger the operating frequency range of the TMR magnetic field sensor, thus having a wider frequency measurement range. However, compared with the push-pull full bridge structure, the single bridge circuit has a lower sensitivity, which is only half of the full bridge TMR magnetic field sensor. Summary of the invention

[0006] The object of the present invention is to provide a TMR magnetic field sensor with a wide measurement frequency range.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The TMR magnetic field sensor comprises TMR units connected to form a full-bridge circuit, wherein each bridge arm of the full-bridge circuit is provided with a TMR unit, the TMR units on adjacent bridge arms are sensitive to external magnetic fields in opposite directions, and the TMR units on opposite bridge arms are sensitive to external magnetic fields in the same direction, and the four bridge arms of the full-bridge circuit intersect in pairs to form four intersections in total, two power supply terminals are arranged at two opposite intersections, and two output terminals are arranged at other two opposite intersections, one of the two power supply terminals is connected to a power supply, and the other is grounded; and the sensor also comprises at least one negative capacitance circuit, wherein the negative capacitance circuit is connected in parallel with the TMR unit on a bridge arm of the full-bridge circuit, one end of the negative capacitance circuit is connected to the grounded power supply terminal, and the other end is connected to the output terminal, and the equivalent capacitances at both ends of the negative capacitance circuit and the parasitic capacitances of the TMR unit connected in parallel with the negative capacitance circuit have opposite signs.

[0009] Furthermore, the equivalent capacitance value of the negative capacitance circuit is 0.5 to 5 times the parasitic capacitance value of the TMR unit connected in parallel therewith.

[0010] Furthermore, the negative capacitance circuit includes an operational amplifier, a first resistor, a second resistor and a capacitor; the inverting input terminal of the operational amplifier is connected to an output terminal, and the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via the first resistor, the non-inverting input terminal of the operational amplifier is connected to the grounded power supply terminal via the capacitor, and the non-inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier via the second resistor.

[0011] Furthermore, each TMR unit is respectively connected in parallel with a negative capacitance circuit, one end of the negative capacitance circuit is connected to one end of the TMR unit connected in parallel therewith connected to the output terminal, and the other end is connected to one end of the TMR unit connected in parallel therewith connected to the power supply terminal.

[0012] Furthermore, the negative capacitance circuit includes an operational amplifier, a first resistor, a second resistor and a capacitor; the inverting input terminal of the operational amplifier is connected to one end of the TMR unit connected in parallel with the operational amplifier and connected to the output terminal, and the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via the first resistor, and the non-inverting input terminal of the operational amplifier is connected to one end of the TMR unit connected in parallel with the operational amplifier and connected to the power supply terminal via the capacitor, and the non-inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier via the second resistor.

[0013] Furthermore, the resistance values ​​of the first resistor and the second resistor are equal or unequal.

[0014] Furthermore, the first resistor and the second resistor are fixed-resistance resistors or adjustable resistors.

[0015] Furthermore, the bandwidth of the first resistor and the second resistor is below GHz.

[0016] Furthermore, the capacitor is a fixed capacitance or an adjustable capacitor.

[0017] Furthermore, the negative capacitance circuit is integrated with the TMR unit.

[0018] Furthermore, the bandwidth of the operational amplifier is greater than the bandwidth of the TMR magnetic field sensor.

[0019] It can be seen from the above technical scheme that the present invention sets a negative capacitance circuit in parallel with the TMR unit in the TMR magnetic field sensor, and the TMR unit is connected to form a push-pull full-bridge circuit. Since the TMR unit and the negative capacitance circuit are connected in parallel, and the capacitance value of the negative capacitance circuit is close to the parasitic capacitance value of the TMR unit and has an opposite sign, the negative capacitance circuit can compensate for the parasitic capacitance of the push-pull full-bridge circuit. By compensating for the parasitic capacitance of the push-pull full-bridge circuit, the measurement frequency range of the TMR magnetic field sensor is expanded. The present invention compensates for the parasitic capacitance of the full-bridge circuit through the negative capacitance circuit unit, does not need to change the formula of the tunnel magnetoresistance, reduces the research and development cost, and can retain the push-pull full-bridge circuit structure, which is conducive to obtaining a higher sensitivity of the TMR magnetic sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a structural diagram of Embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the connection between a TMR unit and a negative capacitance circuit in Example 1 of the present invention;

[0023] Figure 3 is the equivalent circuit model of embodiment 1 of the present invention;

[0024] Figure 4 A comparison diagram of frequency responses of the TMR magnetic field sensor of Embodiment 1 of the present invention and a TMR magnetic field sensor without capacitance compensation;

[0025] Figure 5 This is a structural diagram of Embodiment 2 of the present invention;

[0026] Figure 6 It is a comparison diagram of the frequency response of Example 2 of the present invention and the TMR magnetic field sensor without capacitor compensation. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present invention in detail, for the convenience of explanation, the drawings showing the device structure will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. It should be noted that the drawings are all in a very simplified form and in an inaccurate proportion, which is only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, the TMR magnetic field sensor of this embodiment includes a TMR unit for realizing external magnetic field sensing, and four TMR units (1, 2, 3, 4) are connected to form a push-pull full-bridge circuit. A TMR unit is arranged on each bridge arm of the full-bridge circuit, and the external magnetic field sensitive directions ( Figure 1 The external magnetic field sensitivity directions of the TMR units on the bridge arms are opposite to those of the first TMR unit 1 and the second TMR unit 2, the third TMR unit 3 and the fourth TMR unit 4, respectively. The external magnetic field sensitivity directions of the TMR units on the relative bridge arms are the same, such as the external magnetic field sensitivity directions of the first TMR unit 1 and the third TMR unit 3, the second TMR unit 2 and the fourth TMR unit 4. The TMR unit can be a single tunnel magnetoresistance (MTJ), or it can be composed of multiple tunnel magnetoresistances connected in series. The TMR magnetic field sensor also includes two power supply terminals and two output terminals. In this embodiment, a first power supply terminal 5 and a second power supply terminal 6 are respectively provided between the first TMR unit 1 and the second TMR unit 2 and between the third TMR unit 3 and the fourth TMR unit. The power supply terminals are used to provide working voltages for the TMR magnetic field sensor chip 31 and the operational amplifier chip. The power supply terminals have a ground connection. The second power supply terminal 6 of this embodiment is grounded, and the first power supply terminal 5 is connected to the power supply. A first output terminal 7 and a second output terminal 8 are respectively provided between the first TMR unit 1 and the fourth TMR unit 4 and between the second TMR unit 2 and the third TMR unit 3. The output terminals are used to output differential voltages reflecting the magnitude of the magnetic field. That is, the four bridge arms of the full-bridge circuit intersect with each other in pairs, forming a total of four intersections, two power supply terminals are arranged at two opposite intersections, and two output terminals are arranged at the other two opposite intersections.

[0030] Combination Figure 1 and Figure 2As shown, in the present embodiment, each TMR unit is connected in parallel with a negative capacitance circuit, and there are 4 negative capacitance circuits (9, 10, 11, 12) and 4 TMR units correspondingly arranged. The following is described by taking the first negative capacitance circuit 9 connected in parallel with the first TMR unit 1 as an example, and the negative capacitance circuit structures of other TMR units are the same. The first negative capacitance circuit 9 comprises an operational amplifier 9-1, a first resistor 9-2, a second resistor 9-3 and a capacitor 9-4. The inverting input of the operational amplifier 9-1 is connected to an end (output terminal) of the first TMR unit 1 connected to the output terminal, and the inverting input of the operational amplifier 9-1 is also connected to the output of the operational amplifier 9-1 through the first resistor 9-1, and the in-phase input of the operational amplifier 9-1 is connected to an end (power supply terminal) of the first TMR unit connected to the power supply terminal through the capacitor 9-4, and the in-phase input of the operational amplifier 9-1 is also connected to the output of the operational amplifier 9-1 through the second resistor 9-2. The capacitor in the negative capacitance circuit can be a fixed-value capacitor or an adjustable capacitor. The resistance values ​​of the first resistor and the second resistor can be equal or unequal. The two resistors can use fixed ordinary resistors or adjustable resistors. The resistor type is preferably a resistor with a large bandwidth to ensure the normal operation of the circuit. The bandwidth of the resistor is below GHz (less than or equal to 1GHz), which is mainly determined by the capacitance of the parasitic capacitance. Usually, to eliminate parasitic capacitance below 15pF, it is necessary to use resistors with a bandwidth of about 1MHz to form a negative capacitance circuit.

[0031] The negative capacitance circuit is used to compensate the parasitic capacitance of the TMR unit and the push-pull full-bridge circuit, such as Figure 2 As shown, under ideal conditions, for operational amplifier 9-1, U+=U-, I+=I-, and U1=U2. but When port b is grounded, Z c1 =jwC1, C1 is the capacitance of capacitor 9-4, j is a negative unit, and w is the angular frequency; at this time, the input impedance of ports a and b is When R1=R2, the impedance between ports a and b exhibits electrical characteristics opposite to those of capacitor 9-4, that is, the impedance between ports a and b and the impedance of capacitor 9-4 change in opposite trends with voltage, that is, the equivalent capacitance at both ends of the negative capacitance circuit and the parasitic capacitance of the TMR unit have opposite signs.

[0032] When operational amplifier 9-1 works, the resistance values ​​of first resistor 9-2 and second resistor 9-3 are equal, so that negative capacitance characteristics equal to capacitor 9-4 are shown between two ends (port a and port b) of TMR unit, so that the negative capacitance can compensate the parasitic capacitance of TMR unit. The 4 TMR units of the present embodiment all have negative capacitance compensation, and after being connected into a push-pull full-bridge circuit, a TMR magnetic field sensor with an extended measurement frequency range can be obtained. The negative capacitance circuit of TMR unit can be prepared using CMOS technology, and integrated with TMR unit, so as to reduce the parasitic capacitance of negative capacitance circuit on the influence of push-pull full-bridge circuit, thereby promoting the frequency performance of TMR magnetic field sensor. The negative capacitance circuit can be connected to the external terminals (power supply terminal, output terminal) of TMR magnetic sensor respectively by drawing PCB, forming a push-pull full-bridge magnetic field sensor with negative capacitance compensation.

[0033] Figure 3 is the equivalent circuit model of the conventional TMR full-bridge circuit in the frequency band below GHz. Figure 3 As shown, the four terminals of the full-bridge circuit are provided with a first parasitic capacitor 36, a second parasitic capacitor 37, a third parasitic capacitor 38, a fourth parasitic capacitor 39, a fifth parasitic capacitor 40 and a sixth parasitic capacitor 41. The first parasitic capacitor 36, the second parasitic capacitor 37, the third parasitic capacitor 38, the fourth parasitic capacitor 39, the fifth parasitic capacitor 40 and the TMR unit resistance value of each bridge arm jointly determine the frequency response of the TMR full-bridge circuit; the smaller the parasitic capacitance value and the TMR unit resistance value, the slower the output sensitivity of the TMR full-bridge circuit decays as the frequency increases.

[0034] In this embodiment, a negative capacitance circuit is provided in parallel with each TMR unit to compensate for the parasitic capacitance of the TMR unit and the parasitic capacitance of the full-bridge circuit, so as to expand the measurement frequency range of the sensor. Figure 4 The frequency response curve diagram of the TMR magnetic field sensor with a negative capacitance circuit of this embodiment and the frequency response curve diagram of a conventional TMR magnetic field sensor without a negative capacitance circuit obtained by simulation using multisim circuit simulation software are shown. Figure 4Curve 42 is the frequency response curve of a conventional TMR full-bridge magnetic field sensor without negative capacitance compensation, the TMR resistance values ​​of the four bridge arms are all 90kΩ, and the 6 parasitic capacitances are all 15pF; curves 43, 44, 45, and 46 are frequency linear curves of TMR full-bridge magnetic field sensors with different negative capacitance compensation values, respectively. Except for the negative capacitance compensation, the other parameters are the same as those of the TMR full-bridge magnetic field sensor without negative capacitance compensation, wherein curve 43 is the frequency response curve of a TMR magnetic field sensor with -8pF compensation capacitance, curve 44 is the frequency response curve of a TMR magnetic field sensor with -15pF compensation capacitance, curve 45 is the frequency response curve of a TMR magnetic field sensor with -30pF compensation capacitance, and curve 46 is the frequency response curve of a TMR magnetic field sensor with -60pF compensation capacitance.

[0035] from Figure 4 It can be seen that the frequency point at which the sensitivity gain of curve 42 drops by -3dB is about 59kHz, and the frequency points at which the sensitivity gain of curves 43 to 46 drops by -3dB are about 80kHz, 140kHZ, 220kHz and 70kHz respectively. The measurement frequency range of the TMR magnetic field sensor with negative capacitance compensation has been expanded. Moreover, by comparing multiple curves with different compensation negative capacitance values, the selection of compensation capacitors can be guided, such as Figure 4 As shown, when four negative capacitance circuits are set, when the equivalent capacitance value of the negative capacitance circuit is 0.5 to 4 times the parasitic capacitance value of the TMR unit, the effect of expanding the bandwidth can be obtained.

[0036] In order to ensure that the measurement magnetic field frequency range of the TMR magnetic field sensor can be extended, the bandwidth of the operational amplifier should be greater than the bandwidth of the TMR full-bridge magnetic field sensor. In addition, as a preferred technical solution, in order to reduce the resistance value of the TMR unit, the electrode layer of the TMR unit should increase the current cross-section as much as possible, that is, reduce the aspect ratio of the single electrode layer, so that the closer the distance between the two MTJ magnetoresistors (TMR units), the smaller the electrode resistance connecting them, thereby reducing the resistance value of the TMR unit. Due to process limitations, the shortest distance between the two MTJ magnetoresistors is about 2um. At this time, the electrode is connected in the direction of the large MTJ cross-section to obtain the minimum connection electrode resistance.

[0037] Example 2

[0038] In the negative capacitance circuit, it is necessary to connect to the grounded power supply terminal (assuming that port b is grounded) to produce negative capacitance characteristics. Therefore, as another embodiment of the present invention, only a negative capacitance circuit connected to the ground terminal can be provided. Figure 5As shown, the difference between this embodiment and embodiment 1 is that this embodiment only includes the third negative capacitance circuit 11 and the fourth negative capacitance circuit 12. The third negative capacitance circuit 11 and the fourth negative capacitance circuit 12 have the same structure and also include an operational amplifier, a first resistor, a second resistor and a capacitor. The inverting input terminal of the operational amplifier is connected to the second output terminal 8, and the inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier via the first resistor. The in-phase input terminal of the operational amplifier is connected to the grounded second power supply terminal 6 via the capacitor, and the in-phase input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier via the second resistor. In other embodiments, only one negative capacitance circuit connected to the grounded power supply terminal may be provided.

[0039] Figure 6 The frequency response curve diagram of the TMR magnetic field sensor with a negative capacitance circuit and the frequency response curve diagram of the TMR magnetic field sensor without a negative capacitance circuit of this embodiment are obtained by simulation using multisim circuit simulation software. Figure 6 Curve 47 in FIG. 4 is the frequency response curve of the TMR magnetic field sensor without a negative capacitance circuit. The TMR resistance values ​​of the four bridge arms are all 90 kΩ, and the six parasitic capacitances are all 15 pF. Curves 48, 49, 50, 51, and 52 are the frequency response curves of the TMR magnetic field sensor with -8 pF, -15 pF, -30 pF, -75 pF, and -120 pF compensation capacitances, respectively. The equivalent capacitance values ​​of curves 48, 49, 50, 51, and 52 are 0.5, 1, 2, 5, and 8 times the parasitic capacitance value of the TMR unit, respectively. Figure 6 It can be seen that the frequency points at which the sensitivity gain of curves 47, 48, 49, 50, 51, and 52 drops by -3dB are 60kHz, 80kHz, 250kHz, 180kHz, 110kHz, and 60kHz, respectively. When two negative capacitance circuits are set, when the equivalent capacitance value of the negative capacitance circuit is 0.5 to 5 times the parasitic capacitance value of the TMR unit, the effect of expanding the bandwidth can be obtained. When the equivalent capacitance value of the negative capacitance circuit exceeds 8 times the parasitic capacitance value of the TMR unit, there is no effect of expanding the bandwidth. And from Figure 6 It can be seen that the bandwidth of the full-bridge sensor circuit can be improved by compensating with the negative capacitance circuit. As the equivalent capacitance value of the negative capacitance circuit increases, the bandwidth of the sensor shows a trend of first increasing and then decreasing.

[0040] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A TMR magnetic field sensor, comprising a TMR unit connected to form a full-bridge circuit, wherein each bridge arm of the full-bridge circuit is provided with a TMR unit, the TMR units on adjacent bridge arms are sensitive to external magnetic fields in opposite directions, and the TMR units on opposite bridge arms are sensitive to external magnetic fields in the same direction, the four bridge arms of the full-bridge circuit intersect in pairs to form four intersections, two power supply terminals are provided at two opposite intersections, two output terminals are provided at other two opposite intersections, one of the two power supply terminals is connected to a power source, and the other is connected to ground; Features: It also includes at least one negative capacitance circuit, which is connected in parallel with a TMR unit on a bridge arm in the full-bridge circuit, one end of the negative capacitance circuit is connected to a grounded power supply terminal, and the other end is connected to an output terminal, and the equivalent capacitance at both ends of the negative capacitance circuit and the parasitic capacitance of the TMR unit connected in parallel therewith have opposite signs; The negative capacitance circuit includes an operational amplifier, a first resistor, a second resistor and a capacitor; the inverting input terminal of the operational amplifier is connected to an output terminal, and the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via the first resistor, the non-inverting input terminal of the operational amplifier is connected to a grounded power supply terminal via the capacitor, and the non-inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier via the second resistor; the negative capacitance circuit can compensate for the parasitic capacitance of the TMR unit and the full-bridge circuit.

2. The TMR magnetic field sensor according to claim 1, characterized in that: The equivalent capacitance value of the negative capacitance circuit is 0.5 to 5 times the parasitic capacitance value of the TMR unit connected in parallel therewith.

3. The TMR magnetic field sensor according to claim 1, characterized in that: Each of the TMR units is respectively connected in parallel with a negative capacitance circuit, one end of the negative capacitance circuit is connected to one end of the TMR unit connected in parallel therewith connected to the output terminal, and the other end is connected to one end of the TMR unit connected in parallel therewith connected to the power supply terminal.

4. The TMR magnetic field sensor according to claim 3, characterized in that: The negative capacitance circuit includes an operational amplifier, a first resistor, a second resistor and a capacitor; the inverting input terminal of the operational amplifier is connected to one end of the TMR unit connected in parallel with the operational amplifier and connected to the output terminal, and the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via the first resistor, the non-inverting input terminal of the operational amplifier is connected to one end of the TMR unit connected in parallel with the operational amplifier and connected to the power supply terminal via the capacitor, and the non-inverting input terminal of the operational amplifier is also connected to the output terminal of the operational amplifier via the second resistor.

5. The TMR magnetic field sensor according to claim 4, characterized in that: The resistance values ​​of the first resistor and the second resistor are equal or unequal.

6. The TMR magnetic field sensor according to claim 4, characterized in that: The first resistor and the second resistor are fixed-resistance resistors or adjustable resistors.

7. The TMR magnetic field sensor according to claim 4, characterized in that: The bandwidth of the first resistor and the second resistor is below GHz; and / or the capacitor is a capacitor with a fixed capacitance or an adjustable capacitor.

8. The TMR magnetic field sensor according to claim 1, characterized in that: The negative capacitance circuit is integrated with the TMR unit.

9. The TMR magnetic field sensor according to claim 1, characterized in that: The bandwidth of the operational amplifier is greater than the bandwidth of the TMR magnetic field sensor.

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