Tunnel reluctance TMR signal modulation and demodulation method, device, system and chip

Abstract

The invention relates to the technical field of magnetic sensor signal processing, in particular to a tunneling magnetoresistance (TMR) signal modulation and demodulation method, device and system and a chip. The system comprises a first TMR element, a second TMR element, a switch assembly and a differential amplifier, the output end of the first TMR element and the output end of the second TMR element are connected to the differential amplifier through the switch assembly, and the first TMR element and the second TMR element are opposite in sensitive direction and adopt Wheatstone bridge structures with the same bridge circuit configuration; the switch assembly receives a clock signal input by the clock circuit, switches the on-off state based on the phase of the clock signal, alternately gates and modulates an output end signal of the first TMR element or the second TMR element based on the on-off state, and inputs the modulated output end signal of the first TMR element or the second TMR element to the differential amplifier in a time-sharing manner; the differential amplifier carries out differential amplification on the modulated output end signal which is input in a time-sharing mode to obtain an amplified modulation signal. Through the scheme that the structure is simple and complex mechanical modulation is not needed, the low-frequency noise of the TMR signal is effectively suppressed.

Description

Technical Field

[0001] This disclosure relates to the field of magnetic sensor signal processing technology, specifically to a tunnel magnetoresistive (TMR) signal modulation and demodulation method, apparatus, system, and chip. Background Technology

[0002] A tunneling magnetoresistive (TMR) chip is a high-sensitivity magnetic sensor based on the tunneling magnetoresistive effect, capable of accurately measuring weak magnetic fields and current signals. TMR chips typically employ a Wheatstone bridge structure, with each arm containing a TMR sensing element, and adjacent arms having opposite sensing directions. When an external magnetic field is present, the resistance on different arms changes according to the sensing direction, resulting in a bridge output voltage that is linearly related to the external magnetic field, thus enabling accurate measurement of weak magnetic fields.

[0003] However, due to limitations in its operating principle, the TMR chip generates significant 1 / f noise at low frequencies, which severely restricts its accuracy when measuring weak low-frequency magnetic fields. To eliminate this low-frequency noise, modulation and demodulation methods are widely used. These methods separate the TMR chip's output signal from the low-frequency noise in the frequency domain and then use a low-frequency filter to eliminate the noise.

[0004] Currently, the main methods for suppressing low-frequency noise in TMR chips include sigma-delta modulation and flux chopper modulation. sigma-delta modulation uses noise shaping and spectrum shifting techniques to move low-frequency noise to a higher frequency region, followed by low-pass filtering to eliminate the noise. However, this method requires the design of complex sigma-delta modulation circuits, increasing the difficulty and cost of system implementation. Flux chopper modulation utilizes flux concentrators and MEMS structures to modulate the magnetic field signal through mechanical motion to suppress noise. However, this method requires complex magnetic shielding and MEMS mechanical structure design, and is limited by the frequency of mechanical motion, making it difficult to completely eliminate low-frequency noise.

[0005] As mentioned above, existing modulation techniques suffer from problems such as high circuit complexity and difficulty in mechanical structure design, which limit the application of TMR chips in low-frequency high-precision measurement.

[0006] Therefore, in order to overcome the shortcomings of existing modulation techniques and improve the accuracy of TMR chips in measuring low-frequency magnetic fields, there is an urgent need for a TMR signal modulation and demodulation scheme that is simple in structure, does not require complex mechanical modulation, and can effectively suppress low-frequency noise. Summary of the Invention

[0007] To address the problems in related technologies, this disclosure provides a tunnel magnetoresistive (TMR) signal modulation and demodulation method, apparatus, system, and chip.

[0008] In a first aspect, this disclosure provides a tunnel magnetoresistive (TMR) signal modulation and demodulation magnetic sensitive system. The modulation and demodulation system includes: a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The switching assembly is connected to a clock circuit, which generates a clock signal. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly, wherein:

[0009] The first TMR element and the second TMR element are configured as follows: the first TMR element and the second TMR element have opposite sensing directions and adopt the same bridge circuit configuration in a Wheatstone bridge structure, the Wheatstone bridge structure includes at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite; under the action of an external magnetic field, the amplitude of the output signal of the first TMR element and the output signal of the second TMR element are equal and the polarity is opposite;

[0010] The switching component is configured to: receive the clock signal, switch the on / off state based on the phase of the clock signal, alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state, and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner.

[0011] The differential amplifier is configured to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element that are input in a time-division manner to obtain an amplified modulated signal.

[0012] According to an embodiment of this disclosure, the modulation and demodulation system further includes: a synchronous demodulation device connected to the differential amplifier, the synchronous demodulation device including a multiplier and a low-pass filter; the multiplier is connected to the clock circuit, wherein the clock signal received by the multiplier is synchronized with the clock signal received by the switching component;

[0013] The synchronous demodulation device is configured to: receive the amplified modulation signal from the multiplier, multiply the amplified modulation signal with the received clock signal to obtain the demodulated signal, filter out low-frequency noise in the demodulated signal based on the low-pass filter, and retain the amplified TMR signal, wherein the TMR signal includes: the output signal of the first TMR element or the output signal of the second TMR element.

[0014] According to embodiments of this disclosure, a Wheatstone bridge structure in which the first TMR element and the second TMR element have opposite sensing directions and employ the same bridge configuration includes:

[0015] Both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure. The full-bridge Wheatstone bridge structure includes a first TMR unit, a second TMR unit, a first basic unit, and a second basic unit. The first basic unit includes a third TMR unit or a first fixed resistor, and the second basic unit includes a fourth TMR unit or a second fixed resistor.

[0016] Wherein, the junction point between the first TMR unit and the first basic unit of the first TMR element is connected to the first output terminal of the first TMR element, the junction point between the first TMR unit and the first basic unit of the second TMR element is connected to the first output terminal of the second TMR element, the junction point between the second TMR unit and the second basic unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction point between the second TMR unit and the second basic unit of the second TMR element is connected to the second output terminal of the second TMR element.

[0017] According to embodiments of this disclosure, the switch assembly includes a first switch, a second switch, a third switch, and a fourth switch;

[0018] The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including:

[0019] The first output terminal of the first TMR element is connected in series with the first switch and then connected to the first input terminal of the differential amplifier; the first output terminal of the second TMR element is connected in series with the second switch and then connected to the first input terminal of the differential amplifier.

[0020] The second output terminal of the first TMR element is connected in series with the third switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the fourth switch and then connected to the second input terminal of the differential amplifier.

[0021] According to embodiments of this disclosure, wherein:

[0022] When the operating voltage polarities of the first and third switches are opposite to those of the second and fourth switches, and the first, second, third, and fourth switches are used to receive the clock signal, then:

[0023] The phase switching on / off state based on the clock signal includes:

[0024] When the clock signal is in the first phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state;

[0025] When the clock signal is in the second phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state;

[0026] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0027] When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element.

[0028] When the operating voltage polarities of the first switch, the second switch, the third switch, and the fourth switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch and the third switch are used to receive the first clock signal, and the second switch and the fourth switch are used to receive the second clock signal. Then:

[0029] The phase switching on / off state based on the clock signal includes:

[0030] When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state;

[0031] When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state;

[0032] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0033] When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

[0034] According to embodiments of this disclosure, a Wheatstone bridge structure in which the first TMR element and the second TMR element have opposite sensing directions and employ the same bridge configuration includes:

[0035] Both the first TMR element and the second TMR element adopt a half-bridge Wheatstone bridge structure, which includes a first TMR unit, a second TMR unit, a first fixed resistor, and a second fixed resistor.

[0036] Wherein, the junction of the first fixed resistor and the second fixed resistor of the first TMR element is connected to the first output terminal of the first TMR element, the junction of the first fixed resistor and the second fixed resistor of the second TMR element is connected to the first output terminal of the second TMR element, the junction of the first TMR unit and the second TMR unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction of the first TMR unit and the second TMR unit of the second TMR element is connected to the second output terminal of the second TMR element.

[0037] According to embodiments of this disclosure, the switching assembly includes a first switch and a second switch;

[0038] The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including:

[0039] The first output terminal of the first TMR element and the first output terminal of the second TMR element are directly connected to the first input terminal of the differential amplifier;

[0040] The second output terminal of the first TMR element is connected in series with the first switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the second switch and then connected to the second input terminal of the differential amplifier.

[0041] According to embodiments of this disclosure, wherein:

[0042] When the operating voltage polarities of the first switch and the second switch are opposite, and the first switch and the second switch are used to receive the clock signal, then:

[0043] The phase switching on / off state based on the clock signal includes:

[0044] When the clock signal is in the first phase, then: the first switch is in the on state and the second switch is in the off state;

[0045] When the clock signal is in the second phase, then: the first switch is in the off state and the second switch is in the on state;

[0046] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0047] When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element.

[0048] When the operating voltage polarities of the first switch and the second switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch is used to receive the first clock signal, and the second switch is used to receive the second clock signal. Then:

[0049] The phase switching on / off state based on the clock signal includes:

[0050] When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch is in the on state and the second switch is in the off state;

[0051] When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch is in the off state and the second switch is in the on state;

[0052] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0053] When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

[0054] According to an embodiment of this disclosure, the frequency value of the clock signal is a preset multiple of the frequency value of the change in the external magnetic field.

[0055] Secondly, this disclosure provides a tunnel magnetoresistive (TMR) signal modulation and demodulation method applied to a TMR signal modulation and demodulation system. The modulation and demodulation system includes: a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The switching assembly is connected to a clock circuit, which generates a clock signal. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly. The first TMR element and the second TMR element have opposite sensing directions and employ a Wheatstone bridge structure with the same bridge configuration. The Wheatstone bridge structure includes at least two TMR units, with each pair of adjacent TMR units having opposite sensing directions. Under the influence of an external magnetic field, the output signals of the first TMR element and the second TMR element have equal amplitudes and opposite polarities. The modulation and demodulation method includes:

[0056] Based on the clock signal received by the switching component, the on / off state of the clock signal is switched based on the phase of the clock signal, and the output signal of the first TMR element or the output signal of the second TMR element is alternately selected and modulated based on the on / off state. The modulated output signal of the first TMR element or the output signal of the second TMR element is then input to the differential amplifier in a time-division manner.

[0057] The differential amplifier is used to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element, which are input in a time-division manner, to obtain the amplified modulated signal.

[0058] According to embodiments of this disclosure, the modulation and demodulation method further includes:

[0059] The multiplier receives the amplified modulation signal and multiplies it with the received clock signal to obtain the demodulated signal. The multiplier is connected to the clock circuit, and the clock signal received by the multiplier is synchronized with the clock signal received by the switching component.

[0060] Low-frequency noise in the demodulated signal is filtered out using a low-pass filter, and the amplified TMR signal is retained. The TMR signal includes either the output signal of the first TMR element or the output signal of the second TMR element.

[0061] Thirdly, this disclosure provides a tunnel magnetoresistive (TMR) signal modulation and demodulation device. The device modulates and demodulates the TMR signal output from a TMR element. The device includes a switching assembly and a differential amplifier. The switching assembly is connected to a clock circuit, which generates a clock signal. The TMR element includes a first TMR element and a second TMR element. The output terminals of the first and second TMR elements are respectively connected to the differential amplifier via the switching assembly.

[0062] The switching component is configured to: receive the clock signal, switch the on / off state based on the phase of the clock signal, alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state, and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner.

[0063] The differential amplifier is configured to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element that are input in a time-division manner to obtain an amplified modulated signal.

[0064] The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The first TMR element and the second TMR element have opposite sensing directions and adopt a Wheatstone bridge structure with the same bridge circuit configuration. The Wheatstone bridge structure contains at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite. Under the action of an external magnetic field, the output signals of the first TMR element and the output signals of the second TMR element have equal amplitudes and opposite polarities.

[0065] According to an embodiment of this disclosure, the modulation and demodulation apparatus further includes: a synchronous demodulation device connected to the differential amplifier, the synchronous demodulation device including a multiplier and a low-pass filter; the multiplier is connected to the clock circuit, wherein the clock signal received by the multiplier is synchronized with the clock signal received by the switching component;

[0066] The synchronous demodulation device is configured to: receive the amplified modulation signal from the multiplier, multiply the amplified modulation signal with the received clock signal to obtain the demodulated signal, filter out low-frequency noise in the demodulated signal based on the low-pass filter, and retain the amplified TMR signal, wherein the TMR signal includes: the output signal of the first TMR element or the output signal of the second TMR element.

[0067] Fourthly, this disclosure provides a chip that includes a modulation and demodulation system according to any one of the first aspects, or a modulation and demodulation device according to any one of the third aspects.

[0068] Fifthly, this disclosure provides an electronic device including the chip described in the fourth aspect.

[0069] According to the technical solution provided in this disclosure, the modulation and demodulation system includes a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The switching assembly is connected to a clock circuit. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly. The first TMR element and the second TMR element are configured as follows: the first TMR element and the second TMR element have opposite sensing directions and adopt the same bridge circuit configuration in a Wheatstone bridge structure. The Wheatstone bridge structure includes at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite. Under the influence of an external magnetic field, the output signals of the first TMR element and the second TMR element have equal amplitudes and opposite polarities. The switching component is configured to: receive a clock signal input from the clock circuit; switch the on / off state based on the phase of the clock signal; alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state; and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner. The differential amplifier is configured to: differentially amplify the time-division input modulated output signal of the first TMR element or the output signal of the second TMR element to obtain an amplified modulated signal.

[0070] The modulation and demodulation scheme provided in this disclosure utilizes two TMR elements with opposite sensitive directions and identical bridge circuit configurations to generate output signals of equal amplitude and opposite polarity under the influence of an external magnetic field. During modulation, a clock-controlled switching component switches the signal path, alternately selecting the output signals of the two TMR elements and modulating the selected TMR element's output signal, causing a frequency shift in the TMR signal, replacing traditional mechanical flux modulation. Since 1 / f noise is mainly concentrated in the low-frequency range, the modulated signal shifts the useful signal to a higher frequency range, thus achieving separation of the signal from low-frequency noise in the frequency domain. Subsequently, a low-pass filter (in the synchronous demodulation device) can filter out the low-frequency noise, effectively suppressing the impact of low-frequency noise on measurement accuracy, thereby improving the accuracy of the TMR chip in measuring low-frequency magnetic fields. In addition, the scheme in this disclosure only requires a switch and a clock signal to achieve signal modulation, the circuit design is simple, the clock quality requirements are low, and the reliability of signal modulation is effectively improved.

[0071] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0072] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0073] Figure 1 This diagram illustrates the structure of a tunnel magnetoresistive (TMR) signal modulation and demodulation system according to an embodiment of the present disclosure.

[0074] Figure 2 This diagram illustrates the structure of a first TMR element and a second TMR element according to a first implementation of the present disclosure.

[0075] Figure 3 This diagram illustrates the structure of another first TMR element and a second TMR element under a first implementation according to an embodiment of this disclosure.

[0076] Figure 4 This diagram illustrates the structure of a first TMR element and a second TMR element under a first implementation according to an embodiment of the present disclosure.

[0077] Figure 5 This diagram illustrates the structure of another first TMR element and a second TMR element under a first implementation according to an embodiment of the present disclosure.

[0078] Figure 6 This diagram illustrates the structure of a first TMR element and a second TMR element according to a second implementation of the present disclosure.

[0079] Figure 7 A schematic diagram of a TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown.

[0080] Figure 8 A schematic diagram of the specific structure of another TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown;

[0081] Figure 9 A schematic diagram showing the waveforms of the first clock signal CLK1 and the second clock signal CLK2 according to an embodiment of the present disclosure is provided.

[0082] Figure 10 A schematic diagram of the specific structure of another TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown;

[0083] Figure 11 A schematic diagram of the specific structure of another TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown;

[0084] Figure 12 This diagram illustrates the structure of another tunnel magnetoresistive (TMR) signal modulation and demodulation system according to an embodiment of the present disclosure.

[0085] Figure 13 A flowchart is shown below illustrating a tunnel magnetoresistive (TMR) signal modulation and demodulation method according to an embodiment of the present disclosure.

[0086] Figure 14 A flowchart is shown for another tunnel magnetoresistive (TMR) signal modulation and demodulation method according to an embodiment of the present disclosure;

[0087] Figure 15 A schematic diagram of a tunnel magnetoresistive (TMR) signal modulation and demodulation apparatus according to an embodiment of the present disclosure is shown. Detailed Implementation

[0088] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings to enable those skilled in the art to readily implement them. Furthermore, for clarity, portions unrelated to the description of exemplary embodiments have been omitted from the drawings.

[0089] In this disclosure, it should be understood that terms such as “comprising” or “having” are intended to indicate the presence of features, figures, steps, behaviors, components, parts or combinations thereof disclosed in this specification, and are not intended to exclude the possibility of the presence or addition of one or more other features, figures, steps, behaviors, components, parts or combinations thereof.

[0090] It should also be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0091] As mentioned above, the existing modulation and demodulation methods for suppressing low-frequency noise in TMR chips have certain limitations. In order to overcome the shortcomings of existing modulation techniques, this disclosure provides a TMR signal modulation and demodulation system that is simple in structure, does not require complex mechanical modulation, and can effectively suppress low-frequency noise.

[0092] Figure 1 A schematic diagram of a tunnel magnetoresistive (TMR) signal modulation and demodulation system according to an embodiment of the present disclosure is shown. Figure 1As shown, the modulation and demodulation system includes: a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The switching assembly is connected to a clock circuit, which generates a clock signal. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly. The power supply terminals of the first TMR element and the second TMR element are respectively connected to a DC power supply Vcc, meaning they share the same DC power supply. This eliminates deviations introduced by power fluctuations. Furthermore, being powered by a DC power supply ensures that the TMR element is always in a DC bias state, resulting in a stable output signal and thus guaranteeing a very stable amplitude of the modulated signal.

[0093] In this disclosure, the TMR device comprises only a basic TMR cell or a fixed resistor, and can be provided in die or simple package form (such as SOT-23). ​​The fixed resistor acts as a voltage divider and is insensitive to external magnetic fields, while the TMR cell is sensitive to external magnetic fields and can be a magnetic tunnel junction (MTJ) structure. The MTJ includes a fixed layer (reference layer), a free layer, and an insulating barrier layer. The magnetization direction of the free layer rotates with changes in the external magnetic field. The external magnetic field changes the resistance of the MTJ by altering the magnetization direction of the free layer, thereby causing a change in the output voltage of the TMR device.

[0094] According to embodiments of this disclosure, the first TMR element and the second TMR element are arranged adjacent to each other, either vertically or horizontally. Simultaneously, the first and second TMR elements have opposite sensing directions; that is, their sensing directions are designed to be 180 degrees opposite to each other. Specifically, the first TMR element is rotated 180 degrees relative to the second TMR element. For example, if the sensing direction of the first TMR element is set to +x (resistance increases with increasing magnetic field), then the sensing direction of the second TMR element is set to -x (resistance decreases with increasing magnetic field). This symmetrical arrangement ensures that their resistance changes in opposite directions under the same external magnetic field, thus converting them into completely inverted voltage signals via a Wheatstone bridge. Furthermore, the first and second TMR elements are manufactured using the same materials and processes to ensure consistent initial resistance, noise characteristics, and sensitivity. Moreover, where manufacturing processes allow, the spatial distance between them is minimized to ensure that the sensed external magnetic field strength is identical, avoiding signal amplitude differences due to magnetic field gradients. In this way, under the influence of an external magnetic field, the output signals of the first TMR element and the second TMR element have equal amplitudes (i.e., the response voltages of the two TMR elements to the external magnetic field are equal) and opposite in polarity. This differential structure essentially converts the magnetic field signal into a pair of common-mode suppressed voltage signals, exhibiting noise common-mode characteristics. Specifically, low-frequency noise (such as 1 / f noise and temperature drift) manifests as common-mode signals in the two adjacent TMR elements, while the effective magnetic field signal is converted into a differential-mode signal due to the reverse sensitivity. This design can enhance the output signal and suppress common-mode interference (such as temperature drift and power supply noise), significantly improving the system's signal-to-noise ratio and achieving a high common-mode rejection ratio and noise suppression capability.

[0095] According to embodiments of this disclosure, the first TMR element and the second TMR element employ a Wheatstone bridge structure with the same bridge configuration. The Wheatstone bridge structure includes at least two TMR units, with each pair of adjacent TMR units having opposite sensitivity directions. That is, on the one hand, the first TMR element and the second TMR element possess structural symmetry and parameter matching. Structural symmetry means that the Wheatstone bridge structures of the two TMR elements are completely identical in circuit topology, materials, processes, and unit arrangement, and that the internal bridge arm connections are the same. Parameter matching means that all corresponding bridge arm TMR units have the same initial resistance, sensitivity, and temperature coefficient, or the same fixed resistance value, ensuring that the output voltage of both bridges is zero (ideal balance state) when there is no magnetic field. On the other hand, although the bridge configurations of the two TMR elements are the same, differential output is achieved through a symmetrical reverse design of the sensitivity direction. In addition to the overall reverse sensitivity direction configuration of the two TMR elements as described above, the sensitivity direction between every two adjacent TMR units within the Wheatstone bridge structure of each TMR element is also opposite. Or, when there are only two non-adjacent TMR units, the sensitivity direction between these two TMR units is also opposite. For example, if the sensitivity directions of TMR1 and TMR2 are opposite, then when the external magnetic field response of TMR1 is ΔR, the response of TMR2 is -ΔR. This internal push-pull design makes its output voltage linearly related to the magnetic field.

[0096] For the implementation of a Wheatstone bridge structure in which the first TMR element and the second TMR element have opposite sensing directions and use the same bridge circuit configuration, this disclosure provides two implementation methods:

[0097] First implementation: Both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure. The full-bridge Wheatstone bridge structure includes a first TMR unit, a second TMR unit, a first basic unit, and a second basic unit. The first basic unit includes a third TMR unit or a first fixed resistor, and the second basic unit includes a fourth TMR unit or a second fixed resistor. That is, in the full-bridge Wheatstone bridge structure, all bridge arms can include only TMR units, or they can include TMR units and fixed resistors, as long as each output terminal of the TMR element is connected to at least one TMR unit, ensuring that the voltage at each output terminal can change with the change of magnetic field strength.

[0098] Figure 2 This diagram illustrates the structure of a first TMR element and a second TMR element according to a first implementation of this disclosure. Figure 2As shown, both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure, which includes a first TMR unit TMR1, a second TMR unit TMR2, a third TMR unit TMR3, and a fourth TMR unit TMR4. The red and black arrows indicate the sensitivity directions of the TMR units. Within the same TMR element, TMR1 and TMR4 have the same sensitivity direction, TMR2 and TMR3 have the same sensitivity direction, and the sensitivity directions of any two adjacent TMR units are opposite (TMR1 and TMR2, TMR2 and TMR4, TMR3 and TMR4, TMR1 and TMR3). For the first TMR element and the second TMR element, the sensitivity direction of the first TMR element is opposite to that of TMR1, and similarly, the sensitivity directions of TMR2, TMR3, and TMR4 are also opposite.

[0099] Figure 3 This diagram illustrates the structure of another first TMR element and a second TMR element under a first implementation according to an embodiment of this disclosure. Figure 3 As shown, both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure, which includes a first TMR unit TMR1, a second TMR unit TMR2, a first fixed resistor R1, and a second fixed resistor R2. Similarly, the sensing directions of the first TMR element and the second TMR element TMR1 and TMR2 are opposite.

[0100] Figure 4 This diagram illustrates the structure of another first TMR element and a second TMR element according to a first implementation of the present disclosure. Figure 4 As shown, both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure, which includes a first TMR unit TMR1, a second TMR unit TMR2, a third TMR unit TMR3, and a second fixed resistor R2. Similarly, the sensing directions of TMR1, TMR2, and TMR3 of the first TMR element and the second TMR element are opposite, respectively.

[0101] Figure 5 This diagram illustrates the structure of another first TMR element and a second TMR element according to a first implementation of the present disclosure. Figure 5As shown, both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure, which includes a first TMR unit TMR1, a second TMR unit TMR2, a fourth TMR unit TMR4, and a first fixed resistor R1. Similarly, the sensing directions of TMR1, TMR2, and TMR3 of the first TMR element and the second TMR element are opposite, respectively.

[0102] Second implementation: Both the first TMR element and the second TMR element adopt a half-bridge Wheatstone bridge structure. Figure 6 This diagram illustrates the structure of a first TMR element and a second TMR element according to a second implementation of this disclosure. Figure 6 As shown, the half-bridge Wheatstone bridge structure includes a first TMR unit TMR1, a second TMR unit TMR2, a first fixed resistor R1, and a second fixed resistor R2. The sensing directions of the first TMR element TMR1 and the second TMR element TMR2 are opposite, and similarly, the sensing directions of the first TMR element TMR2 and the second TMR element TMR2 are also opposite.

[0103] According to an embodiment of this disclosure, the switching component is configured to: receive the clock signal, switch the on / off state based on the phase of the clock signal, alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state, and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner.

[0104] The switching assembly includes multiple switches, all of which can achieve active modulation and control of signals through high-frequency switching. The switches in the switching assembly can be only PMOS transistors, only NMOS transistors, or both PMOS transistors and NMOS transistors.

[0105] According to embodiments of this disclosure, the differential amplifier is configured to differentially amplify the time-division-input modulated output signal of the first TMR element or the output signal of the second TMR element to obtain an amplified modulated signal. Since the first and second TMR elements have opposite sensing directions, the differential amplifier outputs a square wave modulated signal whose amplitude envelope is proportional to the magnetic field strength and whose frequency is the same as the clock signal frequency.

[0106] For the first TMR element and the second TMR element, different implementations correspond to different switching components, thus forming different TMR signal modulation and demodulation systems. The following is based on... Figure 1 , combined Figures 2-6The specific implementation methods of the first TMR element and the second TMR element are described in detail through the following four specific embodiments to illustrate the TMR signal modulation and demodulation system.

[0107] Specific embodiments 1 and 2:

[0108] by Figure 1 Combination Figure 2 The structure of the first TMR element and the second TMR element shown is an example of the structure in the first implementation. Figure 7 The diagram shows a specific structural schematic of a TMR signal modulation and demodulation system according to an embodiment of the present disclosure. Figure 8 A schematic diagram of the specific structure of another TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown. Figure 7 and Figure 8 As shown, the junction of the first TMR unit TMR1 and the third TMR unit TMR3 of the first TMR element is connected to the first output terminal of the first TMR element; the junction of the first TMR unit and the third TMR unit of the second TMR element is connected to the first output terminal of the second TMR element; the junction of the second TMR unit TMR2 and the fourth TMR unit TMR4 of the first TMR element is connected to the second output terminal of the first TMR element; and the junction of the second TMR unit TMR2 and the fourth TMR unit TMR4 of the second TMR element is connected to the second output terminal of the second TMR element.

[0109] like Figure 7 and 8 As shown, the corresponding switching components include a first switch, a second switch, a third switch, and a fourth switch. The first output terminal of the first TMR element is connected in series with the first switch and then connected to the first input terminal of the differential amplifier. The first output terminal of the second TMR element is connected in series with the second switch and then connected to the first input terminal of the differential amplifier. The second output terminal of the first TMR element is connected in series with the third switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the fourth switch and then connected to the second input terminal of the differential amplifier.

[0110] In specific embodiment 1, such as Figure 7 As shown, the operating voltage polarities of the first and third switches are opposite to those of the second and fourth switches. For example, a PMOS transistor requires a gate voltage lower than its source voltage (negative voltage) to conduct, while an NMOS transistor requires a gate voltage higher than its source voltage (positive voltage) to conduct. Therefore, PMOS and NMOS transistors are two types of switches with opposite operating voltage polarities. Figure 7In this paper, the first and third switches are both PMOS transistors, and the second and fourth switches are both NMOS transistors.

[0111] Correspondingly, such as Figure 7 As shown, the first, second, third, and fourth switches are used to receive the clock signal CLK. That is, in specific embodiment 1, modulation can be achieved by controlling the four switches with only one clock signal. The clock signal is a periodic square wave signal with two states: high level and low level. At the same time, the clock signals received by the first, second, third, and fourth switches are all either high level or all low level.

[0112] Correspondingly, the phase switching on / off state based on the clock signal includes:

[0113] When the clock signal is in the first phase (e.g., low level), then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state.

[0114] When the clock signal is in the second phase (e.g., high level), then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state.

[0115] Correspondingly, the step of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0116] When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element.

[0117] In specific embodiment 2, such as Figure 8 As shown, the first switch, the second switch, the third switch, and the fourth switch all have the same operating voltage polarity, meaning that all four are either PMOS transistors or NMOS transistors. Figure 8 In this description, the first switch, the second switch, the third switch, and the fourth switch are all PMOS transistors.

[0118] Correspondingly, such as Figure 8As shown, the clock signal includes a first clock signal CLK1 and a second clock signal CLK2. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. Figure 9 The diagram illustrates the waveforms of a first clock signal CLK1 and a second clock signal CLK2 according to an embodiment of this disclosure. The first and third switches are used to receive the first clock signal CLK1, and the second and fourth switches are used to receive the second clock signal CLK2. That is, in specific embodiment 2, four switches are controlled by two clock signals to achieve modulation. At any given moment, the clock signals received by the first and third switches are in phase, and the clock signals received by the second and fourth switches are in phase. For example, if the clock signals received by the first and third switches are high at the current moment, then the clock signals received by the second and fourth switches are low. In the next moment, the clock signals received by the first and third switches will be low, and the clock signals received by the second and fourth switches will be high.

[0119] Correspondingly, the phase switching on / off state based on the clock signal includes:

[0120] When the first clock signal is in the first phase (e.g., low level) and the second clock signal is in the second phase (e.g., high level), then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state.

[0121] When the first clock signal is in the second phase (e.g., high level) and the second clock signal is in the first phase (e.g., low level), then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state.

[0122] Correspondingly, the step of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0123] When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

[0124] Specific embodiments 3 and 4:

[0125] by Figure 1 Combination Figure 6 The structure of the first TMR element and the second TMR element shown is an example of the second implementation. Figure 10 A schematic diagram of the specific structure of another TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown. Figure 11 A schematic diagram of the specific structure of another TMR signal modulation and demodulation system according to an embodiment of the present disclosure is shown. Figure 10 and 11 As shown, the junction of the first fixed resistor R1 and the second fixed resistor R2 of the first TMR element is connected to the first output terminal of the first TMR element, the junction of the first fixed resistor R1 and the second fixed resistor R2 of the second TMR element is connected to the first output terminal of the second TMR element, the junction of the first TMR unit TMR1 and the second TMR unit TMR2 of the first TMR element is connected to the second output terminal of the first TMR element, and the junction of the first TMR unit TMR1 and the second TMR unit TMR2 of the second TMR element is connected to the second output terminal of the second TMR element.

[0126] like Figure 10 and 11 As shown, the corresponding switching assembly includes a first switch and a second switch. The first output terminal of the first TMR element and the first output terminal of the second TMR element are directly connected to the first input terminal of the differential amplifier. The second output terminal of the first TMR element is connected in series with the first switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the second switch and then connected to the second input terminal of the differential amplifier.

[0127] Correspondingly, the output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including:

[0128] The first output terminal of the first TMR element and the first output terminal of the second TMR element are directly connected to the first input terminal of the differential amplifier; the second output terminal of the first TMR element is connected in series with the first switch CLK1 and then connected to the second input terminal of the differential amplifier; the second output terminal of the second TMR element is connected in series with the second switch CLK2 and then connected to the second input terminal of the differential amplifier.

[0129] In specific embodiment 3, such as Figure 10As shown, the first switch and the second switch operate at opposite voltage polarities; the first switch is a PMOS transistor, and the second switch is an NMOS transistor. Correspondingly, as... Figure 10 As shown, the first switch and the second switch are used to receive the clock signal CLK. That is, in specific embodiment 3, modulation can be achieved by controlling the two switches with only one clock signal.

[0130] Correspondingly, the phase switching on / off state based on the clock signal includes:

[0131] When the clock signal is in the first phase (e.g., low level), then: the first switch is in the on state and the second switch is in the off state.

[0132] When the clock signal is in the second phase (e.g., high level), then: the first switch is in the off state and the second switch is in the on state.

[0133] Correspondingly, the step of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0134] When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element.

[0135] In specific embodiment 4, such as Figure 11 As shown, the first switch and the second switch operate at the same voltage polarity, meaning both are either PMOS transistors or both are NMOS transistors. Figure 11 In this example, the first and second switches are described as both being PMOS transistors.

[0136] Correspondingly, such as Figure 11As shown, the clock signals include a first clock signal CLK1 and a second clock signal CLK2. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch is used to receive the first clock signal CLK1, and the second switch is used to receive the second clock signal CLK2. That is, in specific embodiment 4, two clock signals are used to control two switches respectively to achieve modulation. For example, at the current moment, if the clock signal received by the first switch is high, then the clock signal received by the second switch is low. At the next moment, the clock signal received by the first switch will be low, and the clock signal received by the second switch will be high.

[0137] Correspondingly, the phase switching on / off state based on the clock signal includes:

[0138] When the first clock signal is in the first phase (e.g., low level) and the second clock signal is in the second phase (e.g., high level), then the first switch is in the on state and the second switch is in the off state.

[0139] When the first clock signal is in the second phase (e.g., high level) and the second clock signal is in the first phase (e.g., low level), then the first switch is in the off state and the second switch is in the on state.

[0140] Correspondingly, the step of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0141] When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

[0142] For the full-bridge scheme based on the first implementation method in specific embodiments 1 and 2, since the output terminals of the first TMR element and the second TMR element are connected to different input terminals of the differential amplifier through different switch combinations, the output signals of the two elements can be clearly separated and selected under different phases of the clock signal, reducing interference between signals and improving signal quality and accuracy. In addition, the inverse response of the first TMR element and the second TMR element doubles the amplitude of the differential signal, improving sensitivity and signal-to-noise ratio. This full-bridge scheme is suitable for high-precision signal processing scenarios, such as scientific experiments requiring high-precision measurements and precision instrument manufacturing, where the accuracy and stability of signals are extremely important. The full-bridge scheme can provide more refined signal modulation and separation functions to meet the needs of these scenarios.

[0143] For the half-bridge scheme based on the second implementation method in specific embodiments 3 and 4, compared with the full-bridge scheme, the half-bridge scheme uses only two switches, resulting in a simpler circuit structure, reduced component count and circuit complexity, thereby lowering hardware and manufacturing costs. Furthermore, due to the reduced number of switches, the number of switching operations during signal processing is relatively low, leading to a corresponding reduction in overall system power consumption. This is highly advantageous for applications with strict power consumption limitations. This half-bridge scheme is suitable for cost-sensitive consumer electronics and low-power applications, such as ordinary home electronics and portable devices. These products are typically cost-sensitive and have relatively low signal processing requirements. The half-bridge scheme can meet basic signal processing needs while sacrificing some performance to reduce costs, making it suitable for these scenarios. It is also suitable for battery-powered devices, such as smartwatches and wireless sensors, which require minimizing power consumption to extend battery life. The low-power characteristics of the half-bridge scheme make it an ideal choice for these applications. In practical applications, the appropriate implementation scheme can be selected based on the specific application scenario.

[0144] Furthermore, in specific embodiments 1 and 3, the switching assembly includes two sets of switches with opposite operating voltage polarities. In this case, all switches can be synchronously controlled by a single clock signal to achieve signal modulation. This reduces system complexity by using a single clock signal, avoids multi-clock synchronization problems, reduces signal wiring resources, and simplifies timing control. In addition, the complementary characteristics of PMOS and NMOS ensure that the switches do not overlap during high-low level switching (no "shoot-through current"), resulting in low static power consumption and thus reducing system power consumption. In specific embodiments 2 and 4, all switches in the switching assembly are PMOS (or all are NMOS). Although dual clock signals are used to control all switches, the good process matching of the same type of MOS transistors and the high consistency of the switches reduce signal distortion caused by device differences. Furthermore, the on-resistance of the same type of switches is consistent, thereby reducing modulation signal amplitude error. At the same time, the inverted clock strictly ensures that the switches alternately conduct, avoiding signal competition (such as dead time control), making the timing precise and controllable.

[0145] In practical applications, different specific implementation methods can be flexibly selected according to the application scenario and actual needs to balance indicators such as power consumption, area, accuracy and speed, and adapt to different TMR signal modulation and demodulation requirements.

[0146] According to embodiments of this disclosure, the frequency of the clock signal is a preset multiple of the frequency of the external magnetic field change, such as 10 times or more. To accurately capture and record the complete change process of the TMR signal generated by the external magnetic field change, the clock signal needs to be sampled at a sufficiently high frequency. If the clock signal frequency is too low, insufficient sampling may occur, leading to signal distortion and an inability to accurately reflect the changes in the external magnetic field. Based on system performance requirements (e.g., system resolution, response speed), the clock signal frequency can be set to a corresponding multiple of the external magnetic field change frequency. This ensures multiple samplings within a magnetic field change cycle, thereby acquiring richer signal information and improving the accuracy and completeness of the sampling.

[0147] The modulation and demodulation scheme provided in this disclosure utilizes two TMR elements with opposite sensitive directions and identical bridge circuit configurations to generate output signals of equal amplitude and opposite polarity under the influence of an external magnetic field. During modulation, a clock-controlled switching component switches the signal path, alternately selecting the output signals of the two TMR elements and modulating the selected TMR element's output signal, causing a frequency shift in the TMR signal, replacing traditional mechanical flux modulation. Since 1 / f noise is mainly concentrated in the low-frequency range, the modulated signal shifts the useful signal to a higher frequency range, thus achieving separation of the signal from low-frequency noise in the frequency domain. Subsequently, a low-pass filter (in the synchronous demodulation device) can filter out the low-frequency noise, effectively suppressing the impact of low-frequency noise on measurement accuracy, thereby improving the accuracy of the TMR chip in measuring low-frequency magnetic fields. In addition, the scheme in this disclosure only requires a switch and a clock signal to achieve signal modulation, the circuit design is simple, the clock quality requirements are low, and the reliability of signal modulation is effectively improved.

[0148] Figure 12 This diagram illustrates the structure of another tunnel magnetoresistive (TMR) signal modulation and demodulation system according to an embodiment of the present disclosure, as shown below. Figure 12 As shown, the modulation and demodulation system, in addition to the first TMR element, the second TMR element, the switching assembly, and the differential amplifier, also includes: a synchronous demodulation device connected to the differential amplifier, the synchronous demodulation device including a multiplier and a low-pass filter; the multiplier is connected to the clock circuit, wherein the clock signal received by the multiplier is synchronized with the clock signal received by the switching assembly.

[0149] According to an embodiment of this disclosure, the synchronous demodulation device is configured to: receive the amplified modulation signal from the multiplier, multiply the amplified modulation signal with the received clock signal to obtain a demodulated signal, filter out low-frequency noise in the demodulated signal based on the low-pass filter, and retain the amplified TMR signal, wherein the TMR signal includes: the output signal of the first TMR element or the output signal of the second TMR element.

[0150] Figure 13A flowchart illustrating a tunnel magnetoresistive (TMR) signal modulation and demodulation method according to an embodiment of this disclosure is shown. The modulation and demodulation method is applied to a TMR signal modulation and demodulation system, which includes: a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The switching assembly is connected to a clock circuit for generating a clock signal. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly. The first TMR element and the second TMR element have opposite sensing directions and employ a Wheatstone bridge structure with the same bridge configuration. The Wheatstone bridge structure includes at least two TMR units, with each pair of adjacent TMR units having opposite sensing directions. Under the influence of an external magnetic field, the output signals of the first TMR element and the second TMR element have equal amplitudes and opposite polarities.

[0151] like Figure 13 As shown, the modulation and demodulation method includes the following steps S1310 to S1320:

[0152] In step S1310, based on the clock signal received by the switching component, the on / off state of the clock signal is switched based on the phase of the clock signal, and the output signal of the first TMR element or the output signal of the second TMR element is alternately selected and modulated based on the on / off state. The modulated output signal of the first TMR element or the output signal of the second TMR element is then input to the differential amplifier in a time-division manner.

[0153] In step S1320, the modulated output signal of the first TMR element or the output signal of the second TMR element, which are input in a time division manner, are differentially amplified based on the differential amplifier to obtain the amplified modulated signal.

[0154] Figure 14 A flowchart illustrating another tunnel magnetoresistive (TMR) signal modulation and demodulation method according to an embodiment of this disclosure is shown. Figure 14 As shown, in addition to steps S1310 to S1320, the modulation and demodulation method includes the following steps S1330 to S1340:

[0155] In step S1330, based on the multiplier receiving the amplified modulation signal, the amplified modulation signal is multiplied with the received clock signal to obtain the demodulated signal. The multiplier is connected to the clock circuit, and the clock signal received by the multiplier is synchronized with the clock signal received by the switching component.

[0156] In step S1340, low-frequency noise in the demodulated signal is filtered out based on a low-pass filter, and the amplified TMR signal is retained. The TMR signal includes the output signal of the first TMR element or the output signal of the second TMR element.

[0157] According to embodiments of this disclosure, a Wheatstone bridge structure in which the first TMR element and the second TMR element have opposite sensing directions and employ the same bridge configuration includes:

[0158] Both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure. The full-bridge Wheatstone bridge structure includes a first TMR unit, a second TMR unit, a first basic unit, and a second basic unit. The first basic unit includes a third TMR unit or a first fixed resistor, and the second basic unit includes a fourth TMR unit or a second fixed resistor.

[0159] Wherein, the junction point between the first TMR unit and the first basic unit of the first TMR element is connected to the first output terminal of the first TMR element, the junction point between the first TMR unit and the first basic unit of the second TMR element is connected to the first output terminal of the second TMR element, the junction point between the second TMR unit and the second basic unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction point between the second TMR unit and the second basic unit of the second TMR element is connected to the second output terminal of the second TMR element.

[0160] According to embodiments of this disclosure, the switch assembly includes a first switch, a second switch, a third switch, and a fourth switch.

[0161] The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including:

[0162] The first output terminal of the first TMR element is connected in series with the first switch and then connected to the first input terminal of the differential amplifier. The first output terminal of the second TMR element is connected in series with the second switch and then connected to the first input terminal of the differential amplifier.

[0163] The second output terminal of the first TMR element is connected in series with the third switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the fourth switch and then connected to the second input terminal of the differential amplifier.

[0164] in:

[0165] When the operating voltage polarities of the first and third switches are opposite to those of the second and fourth switches, and the first, second, third, and fourth switches are used to receive the clock signal, then:

[0166] The phase switching on / off state based on the clock signal includes:

[0167] When the clock signal is in the first phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state.

[0168] When the clock signal is in the second phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state.

[0169] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0170] When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element.

[0171] When the operating voltage polarities of the first switch, the second switch, the third switch, and the fourth switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch and the third switch are used to receive the first clock signal, and the second switch and the fourth switch are used to receive the second clock signal. Then:

[0172] The phase switching on / off state based on the clock signal includes:

[0173] When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state.

[0174] When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state.

[0175] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0176] When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

[0177] According to embodiments of this disclosure, a Wheatstone bridge structure in which the first TMR element and the second TMR element have opposite sensing directions and employ the same bridge configuration includes:

[0178] Both the first TMR element and the second TMR element adopt a half-bridge Wheatstone bridge structure, which includes a first TMR unit, a second TMR unit, a first fixed resistor, and a second fixed resistor.

[0179] Wherein, the junction of the first fixed resistor and the second fixed resistor of the first TMR element is connected to the first output terminal of the first TMR element, the junction of the first fixed resistor and the second fixed resistor of the second TMR element is connected to the first output terminal of the second TMR element, the junction of the first TMR unit and the second TMR unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction of the first TMR unit and the second TMR unit of the second TMR element is connected to the second output terminal of the second TMR element.

[0180] According to embodiments of this disclosure, the switching assembly includes a first switch and a second switch.

[0181] The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including:

[0182] The first output terminal of the first TMR element and the first output terminal of the second TMR element are directly connected to the first input terminal of the differential amplifier.

[0183] The second output terminal of the first TMR element is connected in series with the first switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the second switch and then connected to the second input terminal of the differential amplifier.

[0184] in:

[0185] When the operating voltage polarities of the first switch and the second switch are opposite, and the first switch and the second switch are used to receive the clock signal, then:

[0186] The phase switching on / off state based on the clock signal includes:

[0187] When the clock signal is in the first phase, then: the first switch is in the on state, and the second switch is in the off state.

[0188] When the clock signal is in the second phase, then: the first switch is in the off state and the second switch is in the on state.

[0189] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0190] When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element.

[0191] When the operating voltage polarities of the first switch and the second switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch is used to receive the first clock signal, and the second switch is used to receive the second clock signal. Then:

[0192] The phase switching on / off state based on the clock signal includes:

[0193] When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch is in the on state and the second switch is in the off state.

[0194] When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch is in the off state and the second switch is in the on state.

[0195] The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes:

[0196] When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

[0197] Figure 15 This diagram illustrates a structural schematic of a tunnel magnetoresistive (TMR) signal modulation and demodulation apparatus according to an embodiment of the present disclosure. The modulation and demodulation apparatus is used to modulate and demodulate the TMR signal output from a TMR element, such as... Figure 15 As shown, the modulation and demodulation device includes: a switching assembly and a differential amplifier. The switching assembly is connected to a clock circuit, which generates a clock signal. The TMR element includes: a first TMR element and a second TMR element. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly, wherein:

[0198] The switching component is configured to: receive the clock signal, switch the on / off state based on the phase of the clock signal, alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state, and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner.

[0199] The differential amplifier is configured to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element that are input in a time-division manner to obtain an amplified modulated signal.

[0200] The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The first TMR element and the second TMR element have opposite sensing directions and adopt a Wheatstone bridge structure with the same bridge circuit configuration. The Wheatstone bridge structure contains at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite. Under the action of an external magnetic field, the output signals of the first TMR element and the output signals of the second TMR element have equal amplitudes and opposite polarities.

[0201] According to an embodiment of this disclosure, the modulation and demodulation apparatus further includes: a synchronous demodulation device connected to the differential amplifier, the synchronous demodulation device including a multiplier and a low-pass filter; the multiplier is connected to the clock circuit, wherein the clock signal received by the multiplier is synchronized with the clock signal received by the switching component.

[0202] The synchronous demodulation device is configured to: receive the amplified modulation signal from the multiplier, multiply the amplified modulation signal with the received clock signal to obtain the demodulated signal, filter out low-frequency noise in the demodulated signal based on the low-pass filter, and retain the amplified TMR signal, wherein the TMR signal includes: the output signal of the first TMR element or the output signal of the second TMR element.

[0203] This disclosure also provides a chip including a modulation and demodulation system as described in embodiments of this disclosure, or including a modulation and demodulation apparatus as described in embodiments of this disclosure.

[0204] This disclosure also provides an electronic device that includes a chip as described in embodiments of this disclosure.

[0205] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

Claims

1. A tunnel magnetoresistive (TMR) signal modulation and demodulation system, characterized in that, The modulation and demodulation system includes: a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The switching assembly is connected to a clock circuit, which generates a clock signal. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly, wherein: The first TMR element and the second TMR element are configured as follows: the first TMR element and the second TMR element have opposite sensing directions and adopt the same bridge circuit configuration in a Wheatstone bridge structure, the Wheatstone bridge structure includes at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite; under the action of an external magnetic field, the amplitude of the output signal of the first TMR element and the output signal of the second TMR element are equal and the polarity is opposite; The switching component is configured to: receive the clock signal, switch the on / off state based on the phase of the clock signal, alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state, and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner. The differential amplifier is configured to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element that are input in a time-division manner to obtain an amplified modulated signal.

2. The modulation and demodulation system according to claim 1, characterized in that, The modulation and demodulation system further includes: a synchronous demodulation device connected to the differential amplifier, the synchronous demodulation device including a multiplier and a low-pass filter; the multiplier is connected to the clock circuit, wherein the clock signal received by the multiplier is synchronized with the clock signal received by the switching component; The synchronous demodulation device is configured to: receive the amplified modulation signal from the multiplier, multiply the amplified modulation signal with the received clock signal to obtain the demodulated signal, filter out low-frequency noise in the demodulated signal based on the low-pass filter, and retain the amplified TMR signal, wherein the TMR signal includes: the output signal of the first TMR element or the output signal of the second TMR element.

3. The modulation and demodulation system according to claim 1, characterized in that, The Wheatstone bridge structure, in which the first TMR element and the second TMR element have opposite sensing directions and use the same bridge circuit configuration, includes: Both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure. The full-bridge Wheatstone bridge structure includes a first TMR unit, a second TMR unit, a first basic unit, and a second basic unit. The first basic unit includes a third TMR unit or a first fixed resistor, and the second basic unit includes a fourth TMR unit or a second fixed resistor. Wherein, the junction point between the first TMR unit and the first basic unit of the first TMR element is connected to the first output terminal of the first TMR element, the junction point between the first TMR unit and the first basic unit of the second TMR element is connected to the first output terminal of the second TMR element, the junction point between the second TMR unit and the second basic unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction point between the second TMR unit and the second basic unit of the second TMR element is connected to the second output terminal of the second TMR element.

4. The modulation and demodulation system according to claim 3, characterized in that, The switching assembly includes a first switch, a second switch, a third switch, and a fourth switch; The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including: The first output terminal of the first TMR element is connected in series with the first switch and then connected to the first input terminal of the differential amplifier; the first output terminal of the second TMR element is connected in series with the second switch and then connected to the first input terminal of the differential amplifier. The second output terminal of the first TMR element is connected in series with the third switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the fourth switch and then connected to the second input terminal of the differential amplifier.

5. The modulation and demodulation system according to claim 4, characterized in that, in: When the operating voltage polarities of the first and third switches are opposite to those of the second and fourth switches, and the first, second, third, and fourth switches are used to receive the clock signal, then: The phase switching on / off state based on the clock signal includes: When the clock signal is in the first phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state; When the clock signal is in the second phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element. When the operating voltage polarities of the first switch, the second switch, the third switch, and the fourth switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch and the third switch are used to receive the first clock signal, and the second switch and the fourth switch are used to receive the second clock signal. Then: The phase switching on / off state based on the clock signal includes: When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state; When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

6. The modulation and demodulation system according to claim 1, characterized in that, The Wheatstone bridge structure, in which the first TMR element and the second TMR element have opposite sensing directions and use the same bridge circuit configuration, includes: Both the first TMR element and the second TMR element adopt a half-bridge Wheatstone bridge structure, which includes a first TMR unit, a second TMR unit, a first fixed resistor, and a second fixed resistor. Wherein, the junction of the first fixed resistor and the second fixed resistor of the first TMR element is connected to the first output terminal of the first TMR element, the junction of the first fixed resistor and the second fixed resistor of the second TMR element is connected to the first output terminal of the second TMR element, the junction of the first TMR unit and the second TMR unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction of the first TMR unit and the second TMR unit of the second TMR element is connected to the second output terminal of the second TMR element.

7. The modulation and demodulation system according to claim 6, characterized in that, The switching assembly includes a first switch and a second switch; The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including: The first output terminal of the first TMR element and the first output terminal of the second TMR element are directly connected to the first input terminal of the differential amplifier; The second output terminal of the first TMR element is connected in series with the first switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the second switch and then connected to the second input terminal of the differential amplifier.

8. The modulation and demodulation system according to claim 7, characterized in that, in: When the operating voltage polarities of the first switch and the second switch are opposite, and the first switch and the second switch are used to receive the clock signal, then: The phase switching on / off state based on the clock signal includes: When the clock signal is in the first phase, then: the first switch is in the on state and the second switch is in the off state; When the clock signal is in the second phase, then: the first switch is in the off state and the second switch is in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element. When the operating voltage polarities of the first switch and the second switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch is used to receive the first clock signal, and the second switch is used to receive the second clock signal. Then: The phase switching on / off state based on the clock signal includes: When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch is in the on state and the second switch is in the off state; When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch is in the off state and the second switch is in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

9. The modulation and demodulation system according to claim 1, characterized in that, in, The frequency value of the clock signal is a preset multiple of the frequency value of the change in the external magnetic field.

10. A method for modulation and demodulation of tunnel magnetoresistive (TMR) signals, applied to a TMR signal modulation and demodulation system, characterized in that, The modulation and demodulation system includes: a first TMR element, a second TMR element, a switching assembly, and a differential amplifier. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The switching assembly is connected to a clock circuit, which generates a clock signal. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly. The first TMR element and the second TMR element have opposite sensing directions and adopt a Wheatstone bridge structure with the same bridge circuit configuration. The Wheatstone bridge structure includes at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite. Under the influence of an external magnetic field, the output signals of the first TMR element and the second TMR element have equal amplitudes and opposite polarities. The modulation and demodulation method includes: Based on the clock signal received by the switching component, the on / off state of the clock signal is switched based on the phase of the clock signal, and the output signal of the first TMR element or the output signal of the second TMR element is alternately selected and modulated based on the on / off state. The modulated output signal of the first TMR element or the output signal of the second TMR element is then input to the differential amplifier in a time-division manner. The differential amplifier is used to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element, which are input in a time-division manner, to obtain the amplified modulated signal.

11. The modulation and demodulation method according to claim 10, characterized in that, The modulation and demodulation method further includes: The multiplier receives the amplified modulation signal and multiplies it with the received clock signal to obtain the demodulated signal. The multiplier is connected to the clock circuit, and the clock signal received by the multiplier is synchronized with the clock signal received by the switching component. Low-frequency noise in the demodulated signal is filtered out using a low-pass filter, and the amplified TMR signal is retained. The TMR signal includes either the output signal of the first TMR element or the output signal of the second TMR element.

12. The modulation and demodulation method according to claim 10, characterized in that, The Wheatstone bridge structure, in which the first TMR element and the second TMR element have opposite sensing directions and use the same bridge circuit configuration, includes: Both the first TMR element and the second TMR element adopt a full-bridge Wheatstone bridge structure. The full-bridge Wheatstone bridge structure includes a first TMR unit, a second TMR unit, a first basic unit, and a second basic unit. The first basic unit includes a third TMR unit or a first fixed resistor, and the second basic unit includes a fourth TMR unit or a second fixed resistor. Wherein, the junction point between the first TMR unit and the first basic unit of the first TMR element is connected to the first output terminal of the first TMR element, the junction point between the first TMR unit and the first basic unit of the second TMR element is connected to the first output terminal of the second TMR element, the junction point between the second TMR unit and the second basic unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction point between the second TMR unit and the second basic unit of the second TMR element is connected to the second output terminal of the second TMR element.

13. The modulation and demodulation method according to claim 12, characterized in that, The switching assembly includes a first switch, a second switch, a third switch, and a fourth switch; The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including: The first output terminal of the first TMR element is connected in series with the first switch and then connected to the first input terminal of the differential amplifier; the first output terminal of the second TMR element is connected in series with the second switch and then connected to the first input terminal of the differential amplifier. The second output terminal of the first TMR element is connected in series with the third switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the fourth switch and then connected to the second input terminal of the differential amplifier.

14. The modulation and demodulation method according to claim 13, characterized in that, in: When the operating voltage polarities of the first and third switches are opposite to those of the second and fourth switches, and the first, second, third, and fourth switches are used to receive the clock signal, then: The phase switching on / off state based on the clock signal includes: When the clock signal is in the first phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state; When the clock signal is in the second phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element. When the operating voltage polarities of the first switch, the second switch, the third switch, and the fourth switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch and the third switch are used to receive the first clock signal, and the second switch and the fourth switch are used to receive the second clock signal. Then: The phase switching on / off state based on the clock signal includes: When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch and the third switch are in the on state, and the second switch and the fourth switch are in the off state; When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch and the third switch are in the off state, and the second switch and the fourth switch are in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch and the third switch are in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch and the fourth switch are in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

15. The modulation and demodulation method according to claim 10, characterized in that, The Wheatstone bridge structure, in which the first TMR element and the second TMR element have opposite sensing directions and use the same bridge circuit configuration, includes: Both the first TMR element and the second TMR element adopt a half-bridge Wheatstone bridge structure, which includes a first TMR unit, a second TMR unit, a first fixed resistor, and a second fixed resistor. Wherein, the junction of the first fixed resistor and the second fixed resistor of the first TMR element is connected to the first output terminal of the first TMR element, the junction of the first fixed resistor and the second fixed resistor of the second TMR element is connected to the first output terminal of the second TMR element, the junction of the first TMR unit and the second TMR unit of the first TMR element is connected to the second output terminal of the first TMR element, and the junction of the first TMR unit and the second TMR unit of the second TMR element is connected to the second output terminal of the second TMR element.

16. The modulation and demodulation method according to claim 15, characterized in that, The switching assembly includes a first switch and a second switch; The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier via the switching assembly, including: The first output terminal of the first TMR element and the first output terminal of the second TMR element are directly connected to the first input terminal of the differential amplifier; The second output terminal of the first TMR element is connected in series with the first switch and then connected to the second input terminal of the differential amplifier. The second output terminal of the second TMR element is connected in series with the second switch and then connected to the second input terminal of the differential amplifier.

17. The modulation and demodulation method according to claim 16, characterized in that, in: When the operating voltage polarities of the first switch and the second switch are opposite, and the first switch and the second switch are used to receive the clock signal, then: The phase switching on / off state based on the clock signal includes: When the clock signal is in the first phase, then: the first switch is in the on state and the second switch is in the off state; When the clock signal is in the second phase, then: the first switch is in the off state and the second switch is in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the clock signal to obtain the modulated output signal of the second TMR element. When the operating voltage polarities of the first switch and the second switch are the same, the clock signal includes a first clock signal and a second clock signal. The first clock signal and the second clock signal have the same frequency, and the second clock signal is the inverted signal of the first clock signal. The first switch is used to receive the first clock signal, and the second switch is used to receive the second clock signal. Then: The phase switching on / off state based on the clock signal includes: When the first clock signal is in the first phase and the second clock signal is in the second phase, then: the first switch is in the on state and the second switch is in the off state; When the first clock signal is in the second phase and the second clock signal is in the first phase, then: the first switch is in the off state and the second switch is in the on state; The method of alternately selecting and modulating the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state includes: When the first switch is in the ON state, the output signal of the first TMR element is selected, and the output signal of the first TMR element is modulated based on the first clock signal to obtain the modulated output signal of the first TMR element; when the second switch is in the ON state, the output signal of the second TMR element is selected, and the output signal of the second TMR element is modulated based on the second clock signal to obtain the modulated output signal of the second TMR element.

18. A tunnel magnetoresistive (TMR) signal modulation and demodulation device, wherein the modulation and demodulation device is used to modulate and demodulate the TMR signal output by a TMR element, characterized in that, The modulation and demodulation device includes a switching assembly and a differential amplifier. The switching assembly is connected to a clock circuit, which generates a clock signal. The TMR element includes a first TMR element and a second TMR element. The output terminals of the first TMR element and the second TMR element are respectively connected to the differential amplifier through the switching assembly, wherein: The switching component is configured to: receive the clock signal, switch the on / off state based on the phase of the clock signal, alternately select and modulate the output signal of the first TMR element or the output signal of the second TMR element based on the on / off state, and input the modulated output signal of the first TMR element or the output signal of the second TMR element to the differential amplifier in a time-division manner. The differential amplifier is configured to differentially amplify the modulated output signal of the first TMR element or the output signal of the second TMR element that are input in a time-division manner to obtain an amplified modulated signal. The first TMR element and the second TMR element are arranged adjacent to each other, and their respective power supply terminals are connected to a DC power supply. The first TMR element and the second TMR element have opposite sensing directions and adopt a Wheatstone bridge structure with the same bridge circuit configuration. The Wheatstone bridge structure contains at least two TMR units, and the sensing directions of every two adjacent TMR units are opposite. Under the action of an external magnetic field, the output signals of the first TMR element and the output signals of the second TMR element have equal amplitudes and opposite polarities.

19. The modulation and demodulation apparatus according to claim 18, characterized in that, The modulation and demodulation device further includes: a synchronous demodulation device, which is connected to the differential amplifier and includes a multiplier and a low-pass filter; the multiplier is connected to the clock circuit, wherein the clock signal received by the multiplier is synchronized with the clock signal received by the switching component; The synchronous demodulation device is configured to: receive the amplified modulation signal from the multiplier, multiply the amplified modulation signal with the received clock signal to obtain the demodulated signal, filter out low-frequency noise in the demodulated signal based on the low-pass filter, and retain the amplified TMR signal, wherein the TMR signal includes: the output signal of the first TMR element or the output signal of the second TMR element.

20. A chip, characterized in that, It includes a modulation and demodulation system according to any one of claims 1 to 9, or a modulation and demodulation apparatus according to any one of claims 18 to 19.

21. An electronic device, characterized in that, Includes the chip described in claim 20.

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