Magnetic field sensor circuit and magnetic field measurement method

Abstract

The invention relates to a magnetic field sensor circuit and a magnetic field measurement method. The present disclosure relates to a magnetic field sensor circuit (300) comprising: a first bridge circuit (122-1) comprising a first series connection of a first magnetoresistor (R1) and a second magnetoresistor (R2); and a second bridge circuit (122-2) comprising a second series connection of a third magnetoresistor (R7) and a fourth magnetoresistor (R8). A first terminal between the first magnetoresistor (R1) and the second magnetoresistor (R2) of the first bridge circuit (122-1) is coupled to a second terminal between the third magnetoresistor (R7) and the fourth magnetoresistor (R8) of the second bridge circuit (122-2). The coupled first and second terminals provide a first output signal of the magnetic field sensor circuit (300).

Description

Technical Field

[0001] The present disclosure relates generally to magnetic field sensors and, more particularly, to magnetic field sensors for differential field sensing and uniform field sensing. Background Art

[0002] In current sensing with an internal busbar and an external busbar (or current rail), attempts are often made to place the sensing elements in an arrangement where a first sensing element is placed above the busbar and a second sensing element is placed adjacent to the first sensing element. This allows the current sensor to differentially sense the current in the busbar. With a differential sensing architecture, the current sensor can be very robust to any uniform stray fields present in the current sensing application. However, there may be sensing arrangements where sensitivity to uniform fields is preferred (e.g., in core-based current sensing or for linear torque sensing).

[0003] Another application is magnetic speed sensing, where differential and / or single-mode sensing is used to detect the speed and direction of rotation of a toothed ferrite wheel or wheel with magnetic domains. As an example, dynamic switching between single-mode and differential-mode reading in a giant magnetoresistor (GMR) is achieved by measuring the resistance drop across a portion of a Wheatstone bridge in single mode. In addition to the disadvantage that Wheatstone bridge readout cannot be used in single mode, this approach is not even applicable to tunnel magnetoresistors (TMR) devices, since the field sensitivity is proportional to the conductance in the GMR, not the resistance. Furthermore, it is difficult to adjust the gain if the sensitivity in the two modes does not match.

[0004] Typically, the sensing concept must be chosen in advance and must be defined at the beginning of the sensor design. Once the architecture is chosen, the overall design attempts to optimize the differential signaling capability or the uniform sensing capability. Furthermore, it is not easy to create a flexible concept and make this choice through simple configuration bits or metal mask configuration without a lot of circuit overhead.

[0005] The state-of-the-art is to choose the sensing principle from the beginning and then optimize the architecture to perfectly fit the application. This approach is very inflexible when it turns out that some applications may have different needs. This becomes even more of a problem if the application requires both modes at the same time. This would require two sensors with different configurations, making the solution non-scalable and increasing costs.

[0006] Therefore, there is a need for a method that provides more flexible current sensing. Summary of the invention

[0007] This need is solved by a magnetic field sensor circuit and a magnetic field sensing method according to the appended claims.

[0008] According to a first aspect, the present disclosure provides a magnetic field sensor circuit. The magnetic field sensor circuit includes a first bridge circuit, the first bridge circuit including a first series connection of a first magnetoresistor and a second magnetoresistor. The magnetic field sensor circuit also includes a (separate) second bridge circuit, the second bridge circuit including a second series connection of a third magnetoresistor and a fourth magnetoresistor. A first terminal between the first magnetoresistor and the second magnetoresistor of the first bridge circuit is coupled to a second terminal between the third magnetoresistor and the fourth magnetoresistor of the second bridge circuit. The coupled first terminal and the second terminal provide a first output signal of the magnetic field sensor circuit. The first terminal and the second terminal can be short-circuited. In this way, a magnetic field sensor or a current sensor having at least a single-ended output signal can be provided for both differential sensing and uniform field sensing.

[0009] The first bridge circuit and the second bridge circuit may be separate full-Wheatstone bridges or half-Wheatstone bridges, respectively.The magnetic field sensor circuit may be implemented using discrete components or as one or more integrated circuits (ICs).

[0010] In some embodiments, the first magnetoresistor of the first bridge circuit includes a first reference magnetization. The second magnetoresistor of the first bridge circuit includes a second reference magnetization different from the first reference magnetization. The third magnetoresistor of the second bridge circuit includes a second reference magnetization (of the second magnetoresistor). The fourth magnetoresistor of the second bridge circuit includes a first reference magnetization (of the first magnetoresistor).

[0011] In some embodiments, the second reference magnetization is antiparallel to the first reference magnetization. Thus, the second reference magnetization is offset by 180° relative to the first reference magnetization.

[0012] In some embodiments, the first series connection of the first bridge circuit is coupled between the first power terminal and the first ground terminal. The second series connection of the second bridge circuit is coupled between the second power terminal and the second ground terminal. Although the first power terminal and the second power terminal can refer to separate terminals, they can also refer to a common power terminal. Similarly, although the first ground terminal and the second ground terminal can refer to separate terminals, they can also refer to a common ground terminal.

[0013] In some embodiments, a first power supply terminal is coupled to a first series-connected magneto-resistor having a first reference magnetization, and a second power supply terminal is coupled to a second series-connected magneto-resistor having a second reference magnetization different from the first reference magnetization. Here, the power supply is connected to the first series-connected and second series-connected magneto-resistors having different reference magnetizations. Such a configuration can provide sensitivity of the magnetic field sensor circuit for differential field sensing.

[0014] In some embodiments, a first power supply terminal is coupled to a first series-connected magneto-resistor (of a first bridge circuit) having a first reference magnetization, and a second power supply terminal is coupled to a second series-connected magneto-resistor (of a second bridge circuit) having a first reference magnetization. Here, the power supply is connected to the first series-connected and second series-connected magneto-resistors having the same reference magnetization. Such a configuration can provide the sensitivity of the magnetic field sensor circuit for uniform field sensing.

[0015] In some embodiments, a first series connection (of a first bridge circuit) of a first magnetoresistor and a second magnetoresistor is coupled between a first power supply terminal and a first ground terminal, and a second series connection (of a second bridge circuit) of a third magnetoresistor and a fourth magnetoresistor is coupled between a second ground terminal and a third ground terminal. Thus, while the first series connection (of the first bridge circuit) may be coupled between power and ground, the second series connection (of the second bridge circuit) may be coupled between two ground terminals. This configuration may provide sensitivity of the magnetic field sensor circuit for both differential field sensing and uniform field sensing.

[0016] In some embodiments, the first series connection (of the first bridge circuit) of the first magnetoresistors and the second magnetoresistors is coupled between a power supply and ground. The magnetic field sensor circuit may further include a switch circuit configured to switch between different magnetic field sensing modes by modifying a power supply of the first series connection (of the first bridge circuit) or a power supply of the second series connection (of the second bridge circuit).

[0017] In some embodiments, the switch circuit is configured to: couple the second series connection of the third and fourth magnetic resistors between power and ground in a first sensing mode; switch the terminals of the power and ground of the second series connection compared to the first sensing mode in a second sensing mode; and / or couple the second series connection of the third and fourth magnetic resistors between two ground terminals in a third sensing mode. In this way, the magnetic field sensor circuit can be configured for different sensing modes of differential field sensing and / or uniform field sensing.

[0018] In some embodiments, the first bridge circuit includes a third series connection of a fifth magnetoresistor and a sixth magnetoresistor, the third series connection being connected in parallel with the first series connection. Thus, the first bridge circuit may be a full Wheatstone bridge circuit. The second bridge circuit includes a fourth series connection of a seventh magnetoresistor and an eighth magnetoresistor, the fourth series connection being connected in parallel with the second series connection. Thus, the second bridge circuit may be a full Wheatstone bridge circuit. The third terminal between the fifth magnetoresistor and the sixth magnetoresistor of the first bridge circuit is coupled to the fourth terminal between the seventh magnetoresistor and the eighth magnetoresistor of the second bridge circuit. The coupled third terminal and the fourth terminal may provide a second output signal of the magnetic field sensor circuit. The third terminal and the fourth terminal may be short-circuited. In this way, a current sensor having a differential output signal may be provided.

[0019] In some embodiments, the fifth magnetoresistor of the first bridge circuit includes a second reference magnetization (of the second magnetoresistor), the sixth magnetoresistor of the first bridge circuit includes a first reference magnetization (of the first magnetoresistor), the seventh magnetoresistor of the second bridge circuit includes the first reference magnetization, and the eighth magnetoresistor of the second bridge circuit includes the second reference magnetization.

[0020] In some embodiments, the magnetic field sensor circuit further includes a differential amplifier. A first input terminal of the differential amplifier is coupled to the first output signal, and a second input terminal of the differential amplifier is coupled to the second output signal of the magnetic field sensor. The differential amplifier can be implemented as an operational amplifier (Op-Amp) or an operational transconductance amplifier (OTA). An OTA is a special type of amplifier that provides an output current proportional to the difference between its input voltages. Unlike a voltage amplifier (operational amplifier or op amp) that provides an output voltage proportional to the input voltage difference, an OTA amplifies the input voltage difference by converting the input voltage difference into an output current.

[0021] In some embodiments, the magnetoresistors of the first bridge circuit and the second bridge circuit are giant magnetoresistors (GMR) or tunnel magnetoresistors (TMR).

[0022] According to another aspect, the present disclosure provides a magnetic field measurement method. The method includes: providing a first bridge circuit, the first bridge circuit including a first series connection of a first magnetoresistor and a second magnetoresistor; providing a second bridge circuit, the second bridge circuit including a second series connection of a third magnetoresistor and a fourth magnetoresistor; coupling a first terminal between the first magnetoresistor and the second magnetoresistor of the first bridge circuit to a second terminal between the third magnetoresistor and the fourth magnetoresistor of the second bridge circuit; and providing an output signal of a magnetic field sensor circuit at the coupled first and second terminals.

[0023] In some embodiments, the first bridge circuit includes a third series connection of a fifth magnetoresistor and a sixth magnetoresistor, the third series connection being connected in parallel with the first series connection. The second bridge circuit includes a fourth series connection of a seventh magnetoresistor and an eighth magnetoresistor, the fourth series connection being connected in parallel with the second series connection. The method may also include coupling a third terminal between the fifth magnetoresistor and the sixth magnetoresistor of the first bridge circuit to a fourth terminal between the seventh magnetoresistor and the eighth magnetoresistor of the second bridge circuit, and providing a second output signal of the magnetic field sensor circuit at the coupled third and fourth terminals.

[0024] In some embodiments, the first series connection of the first and second magnetoresistors may be coupled between a power supply and ground.The method may include switching between different sensing modes by modifying a power supply of the first series connection and / or a power supply of the second series connection.

[0025] In some embodiments, switching between different sensing modes includes: in a first sensing mode, coupling a second series connection of the third magnetic resistor and the fourth magnetic resistor between a power supply and a ground; in a second sensing mode, switching terminals of the power supply and the ground of the second series connection compared to the first sensing mode; and / or in a third sensing mode, coupling the second series connection of the third magnetic resistor and the fourth magnetic resistor between two ground terminals.

[0026] The present disclosure proposes a dual bridge approach to address differential sensing on current rails. In addition, by grounding one of the bridges, one sensing mode can be switched to another sensing mode, and be sensitive to uniform fields. This can be done permanently, or even with a user command to allow two signals to be measured by a single sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Some examples of apparatus and / or methods will be described below, by way of example only, and with reference to the accompanying drawings, in which

[0028] Figure 1A-Figure 1D shows different magnetic sensing concepts for current sensing and speed sensing to which the present disclosure can be applied;

[0029] Figure 2A A conventional sensor (full) bridge configuration is shown;

[0030] Figure 2B shows a differential amplifier circuit coupled to the Figure 2A Conventional sensor bridge configuration;

[0031] Figure 2C A conventional sensor (half) bridge configuration coupled to an amplifier circuit is shown;

[0032] Figure 3Ashows a sensor bridge configuration according to a first embodiment;

[0033] Figure 3B shows a sensor bridge configuration according to a second embodiment;

[0034] Figure 3C shows a sensor bridge configuration according to a third embodiment; and

[0035] Figure 4 A sensor bridge configuration with an amplifier for output signal amplification is shown. DETAILED DESCRIPTION

[0036] Some examples are now described in more detail with reference to the disclosed drawings. However, other possible examples are not limited to the features of these embodiments described in detail. Other examples may include modifications of features and equivalents and substitutes of features. In addition, the terms used herein to describe certain examples should not limit other possible examples.

[0037] In the description of the entire drawings, the same or similar reference numerals refer to the same or similar elements and / or features, which may be implemented in the same or modified form while providing the same or similar functions. For clarity, the thickness of the lines, layers and / or regions in the drawings may also be exaggerated.

[0038] When "or" is used to combine two elements A and B, this should be understood to disclose all possible combinations, i.e. only A, only B and A and B, unless otherwise explicitly defined in individual cases. As an alternative wording for the same combination, "at least one of A and B" or "A and / or B" can be used. This applies equally to combinations of more than two elements.

[0039] If singular forms such as "a", "an", and "the" are used, and the use of only a single element is not explicitly or implicitly defined as mandatory, additional examples may also use several elements to achieve the same function. If the function is described below as being implemented using multiple elements, additional examples may use a single element or a single processing entity to achieve the same function. It should also be understood that the terms "comprise", "comprising", "including", and / or "comprising" when used describe the presence of specified features, integers, steps, operations, processes, elements, components, and / or groups thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, processes, elements, components, and / or groups thereof.

[0040] Figure 1A-Figure 1D Different magnetic sensing concepts for current sensing and speed sensing applications to which embodiments of the present disclosure may be applied are illustrated.

[0041] Figure 1AA first current sensing concept is shown, where the current rail or busbar 110 is arranged external to the sensor chip or IC (integrated circuit) 120. Figure 1A In FIG. 1 , the sensor IC 120 includes a single magnetic sensing element 122 and is arranged above the busbar 110 for uniform magnetic field sensing. For example, the sensing element 122 may include a (full) Wheatstone bridge arrangement of four magnetoresistors. A magnetoresistors may also be referred to as XMR elements.

[0042] Figure 1B A second current sensing concept is shown, in which the busbar 110 is arranged outside the sensor IC 120. The sensor IC 120 comprises a first sensing element 122-1 arranged above the busbar 110 and a second sensing element 122-2 arranged adjacent to the first sensing element 122-1 and also adjacent to the busbar 110 for differential magnetic field sensing. For example, the two sensing elements 122-1, 122-2 may comprise respective (full) Wheatstone bridge arrangements of four magnetoresistors.

[0043] Figure 1C A third current sensing concept is shown, in which the bus bar 110 is arranged outside the sensor IC 120. The sensor IC 120 includes a first sensing element 122-1 arranged above the bus bar 110 and a second sensing element 122-2 arranged adjacent to the first sensing element 122-1 but also above the bus bar 110 for differential magnetic field sensing. Figure 1C In the example of FIG. 1 , the bus bar 110 includes a slit 112, and the sensor IC 120 is placed above the slit 112. The first sensing element 122-1 can measure the magnetic field generated by the current passing through the bus bar 110 on the left side of the slit 112, and the second sensing element 122-2 can measure the magnetic field generated by the current passing through the bus bar 110 on the right side of the slit 112. For example, the two sensing elements 122-1, 122-2 can include corresponding Wheatstone bridge arrangements of four magnetoresistors.

[0044] Figure 1D A magnetic speed sensing application is illustrated, where differential sensing is used to detect the speed and direction of rotation of a toothed ferrite wheel 130 or a wheel having magnetic domains. The sensor IC 120 is arranged radially outside the wheel 130 and includes two adjacent sensing elements 122-1, 122-2 for differential field sensing. For example, the two sensing elements 122-1, 122-2 may include respective Wheatstone bridge arrangements of four magnetoresistors.

[0045] Figure 2AA conventional sensor IC 120 is illustrated in which a first magnetic sensing element 122-1 is implemented as a first bridge circuit and an adjacent second magnetic sensing element 122-2 is implemented as a second bridge circuit. In the illustrated example, the first bridge circuit 122-1 and the second bridge circuit 122-2 are each implemented as a full Wheatstone bridge for providing a corresponding differential output signal V left and V right A skilled person having the benefit of this disclosure will recognize that the first bridge circuit 122-1 and the second bridge circuit 122-2 may also be implemented as a half-Wheatstone bridge if a single-ended output signal is sufficient. A half-Wheatstone bridge consists of only a single series connection of a first resistor and a second resistor, whereas a full-Wheatstone bridge includes a first series connection of a first magnetic resistor and a second magnetic resistor and a second series connection of a third resistor and a fourth resistor, the first series connection being connected in parallel with the second series connection.

[0046] Figure 2A The first bridge circuit 122-1 shown in (left) includes a first series connection of a first magnetic resistor R1 and a second magnetic resistor R2 coupled between a first power terminal 202-1 and a first ground terminal 204-1. The first power terminal 202-1 is directly coupled to the second magnetic resistor R2. The first ground terminal 204-1 is directly coupled to the first magnetic resistor R1. The first bridge circuit 122-1 also includes a second series connection of a third magnetic resistor R3 and a fourth magnetic resistor R4 coupled between the first power terminal 202-1 and the first ground terminal 204-1, and the second series connection is connected in parallel with the first series connection. The first power terminal 202-1 is directly coupled to the fourth magnetic resistor R4. The first ground terminal 204-1 is directly coupled to the third magnetic resistor R3.

[0047] The first magnetoresistor R1 includes a first reference magnetization (here: to the left), and the second magnetoresistor R2 includes a second reference magnetization (here: to the right) different from the first reference magnetization. The second reference magnetization of the second magnetoresistor R2 may be antiparallel (i.e., 180°) to the first reference magnetization of the first magnetoresistor R1. The third magnetoresistor R3 includes a second reference magnetization (to the right), and the fourth magnetoresistor R4 includes a first reference magnetization (to the left). The first differential output signal (V left ) is provided at a first output terminal (V left+ ) and the second output terminal (V left- )between.

[0048] Figure 2AThe second bridge circuit 122-2 shown in (right) includes a third series connection of a fifth magnetic resistor R5 and a sixth magnetic resistor R6 coupled between the second power terminal 202-2 and the second ground terminal 204-2. The second power terminal 202-2 is directly coupled to the sixth magnetic resistor R6. The second ground terminal 204-2 is directly coupled to the fifth magnetic resistor R5. The second bridge circuit 122-2 also includes a fourth series connection of a seventh magnetic resistor R7 and an eighth magnetic resistor R8 coupled between the second power terminal 202-2 and the second ground terminal 204-2, the fourth series connection being connected in parallel with the third series connection. The second power terminal 202-2 is directly coupled to the eighth magnetic resistor R8. The second ground terminal 204-2 is directly coupled to the seventh magnetic resistor R7.

[0049] The fifth magnetic resistor R5 includes a first reference magnetization (here: to the left), the sixth magnetic resistor R6 includes a second reference magnetization (here: to the right) different from the first reference magnetization. The seventh magnetic resistor R7 includes a second reference magnetization, and the eighth magnetic resistor R8 includes the first reference magnetization. The second differential output signal (V right ) is provided at a third output terminal (V right+ ) and a fourth output terminal (V right- )between.

[0050] A magnetoresistor R1 to R8 is an electronic component whose resistance changes in response to an applied external magnetic field. Some examples of magnetoresistors that can be used are:

[0051] Anisotropic Magnetoresistive (AMR) Components: AMR components utilize the anisotropic magnetoresistive effect, where the resistance of a material changes with the direction of an applied magnetic field. They are commonly used in magnetic field sensing applications such as compasses, position sensors, and contactless current sensing.

[0052] Giant Magnetoresistive (GMR) Element: GMR elements utilize the giant magnetoresistive effect, which occurs in a layered structure of magnetic and non-magnetic materials. GMR sensors have higher sensitivity and lower power consumption than AMR sensors. They are used in applications such as magnetic field sensing, data storage devices (read heads in hard disk drives), and magnetic field imaging.

[0053] Tunnel magnetoresistance (TMR) elements: TMR elements utilize the tunnel magnetoresistance effect, in which resistance changes based on the relative alignment of magnetic layers separated by a thin insulating barrier. TMR sensors exhibit high sensitivity and low power consumption, making them suitable for applications such as magnetic field sensing, spintronics, and magnetic random access memory (MRAM).

[0054] Preferably, all magnetoresistors R1 to R8 are of the same type, for example AMR type, GMR type or TMR type.

[0055] In the context of magnetoresistive elements or magnetoresistors, "reference magnetization" refers to the orientation or alignment of a magnetic field in a particular direction, used as a reference for measuring changes in resistance caused by an external magnetic field. Magnetoresistors (such as AMR, GMR or TMR magnetoresistors) exhibit changes in resistance in response to the orientation of an applied external magnetic field. This change in resistance is generally referred to as the magnetoresistive effect. In order to measure magnetoresistance, a reference magnetization is established within the magnetoresistor. The reference magnetization provides a baseline against which changes in resistance can be detected. In a typical configuration, the magnetoresistor includes multiple layers, including magnetic layers and non-magnetic spacer layers. The reference magnetization is established in one of these layers or in an adjacent magnet or synthetic antiferromagnet. The direction of the reference magnetization remains fixed, allowing the detection of changes in resistance caused by an external magnetic field. When an external magnetic field is applied to the magnetoresistor, the magnetization of the magnetoresistor can be aligned or deviated from the reference magnetization, resulting in a change in resistance. This change in resistance can then be measured and quantified, providing information about the magnitude, direction or other characteristics of the external magnetic field. In summary, the reference magnetization in a magneto-resistor provides a fixed orientation of the magnetic field within the element, used as a reference for measuring the change in resistance induced by an external magnetic field. It is able to detect and quantify magnetic field changes by measuring magnetoresistance.

[0056] Figure 2A The example shows two completely independent sensing element bridges 122-1, 122-2, which have independent differential voltages V left 、V right . Differential voltage V left 、V right It can be further fed to one or more amplifier stages 210 or further processed. Figure 2B As previously mentioned, if a single-ended output signal is sufficient, the first bridge circuit 122-1 and the second bridge circuit 122-2 can also be implemented as a half-Wheatstone bridge. Figure 2C Such an example is illustrated in FIG.

[0057] Figure 2A The sensitivity of the architecture to the differential magnetic field can be expressed as

[0058] V diff (B sig )=-VDDS·S B ·B sig

[0059] Wherein, VDDS represents the power supply voltage at the first power supply terminal 202-1 and the second power supply terminal 202-2, S B represents the sensitivity of the bridge circuits 122-1 and 122-2, and Bsig Represents the strength of the external differential magnetic field.

[0060] Figure 2A-2C The sensitivity of the architecture to uniform fields is zero.

[0061] In order to provide a magnetic field sensor circuit that can be used to measure both uniform magnetic fields and differential magnetic fields, the present disclosure proposes to interconnect two bridge circuits 122-1 and 122-2. FIG. 3A to FIG. 3C Various examples of the resulting magnetic field sensor circuits are shown in .

[0062] exist Figure 3A A first embodiment of a magnetic field sensor circuit 300 having interconnected bridge circuits 122 - 1 , 122 - 2 is shown in FIG.

[0063] Figure 3A The magnetic field sensor circuit 300 and Figure 2A The difference of the magnetic field sensor circuit 120 is that the first output terminal between the first magnetoresistors R1 and R2 (of the first bridge circuit 122-1) and the fourth output terminal between the seventh magnetoresistors R7 and R8 (of the second bridge circuit 122-2) are (directly) coupled or interconnected. In other words, the first output terminal and the fourth output terminal are short-circuited. The coupled first output terminal and the fourth output terminal provide the first output signal Vn of the magnetic field sensor circuit 300. Similarly, the second output terminal between the third magnetoresistors R3 and R4 (of the first bridge circuit 122-1) and the third output terminal between the fifth magnetoresistors R5 and R6 (of the second bridge circuit 122-2) are also (directly) coupled or interconnected. In other words, the second output terminal and the third output terminal are short-circuited. The coupled second output terminal and the third output terminal provide the second output signal Vp of the magnetic field sensor circuit 300. As can be seen, the branches of the different bridge circuits 122-1, 122-2 with different (anti-parallel) reference magnetizations are interconnected or coupled. Likewise, those skilled in the art having the benefit of this disclosure will recognize that if a single-ended output signal is sufficient, the first bridge circuit 122 - 1 and the second bridge circuit 122 - 2 may also be implemented as (directly) coupled or interconnected half-Wheatstone bridges.

[0064] Figure 3A The sensitivity of the architecture to the differential magnetic field can be expressed as

[0065]

[0066] therefore, Figure 2B The sensitivity of the architecture to the differential field is Figure 2A architecture has half the sensitivity to differential fields. Figure 2A Compared with the architecture of Figure 3AThe architecture may have several advantages, which will become apparent below.

[0067] Figure 3A The sensitivity of the architecture to the uniform field can be expressed as

[0068]

[0069] Where V L represents the power supply voltage at the left power supply terminal 202-1, V R represents the power supply voltage at the right power supply terminal 202-2, S BL represents the sensitivity of the left bridge circuit 122-1, S BR represents the sensitivity of the right bridge circuit 122-2, and B hom represents the strength of the external uniform magnetic field. Assuming V R =V L =VDDS and the sensitivity is equal to S BL =S BR , then the sensitivity to the uniform field will be zero. Therefore, if the sensitivity of the left bridge 122-1 and the right bridge 122-2 is the same, then the sensitivity to the uniform field is zero, and Figure 3A The sensing element arrangement is only sensitive to differential fields.

[0070] To implement a uniform field sensor using the proposed interconnect bridge arrangement, one of the bridge supplies can be flipped to have a fully uniform sensor. Figure 3B Shown in.

[0071] Figure 3B The magnetic field sensor circuit 300 and Figure 3A The difference is that the supply voltage VDDS of the right bridge circuit 122-2 is coupled to the lower terminal 204-2 and the ground is coupled to the upper terminal 202-2, while Figure 3A In FIG. 1 , the power supply voltage VDDS is coupled to the upper terminal 202-2 and ground is coupled to the lower terminal 204-2. That is, the power supply of the right bridge circuit 122-2 is relative to Figure 3A Flip. Figure 3B , the ground is directly coupled to the sixth magnetoresistor R6 and the eighth magnetoresistor R8, and the power supply is directly coupled to the fifth magnetoresistor R5 and the seventh magnetoresistor R7.

[0072] Figure 3B The sensitivity of the architecture to the differential field can be expressed as

[0073]

[0074] Thus, if the sensitivity of the left bridge circuit 122-1 and the right bridge circuit 122-2 are the same, the sensitivity to the differential field is zero, and the sensing element arrangement is only sensitive to the uniform field.

[0075] Figure 3B The sensitivity of the architecture to the uniform field can be expressed as

[0076]

[0077] Therefore, if the individual bridge sensitivities of the left and right bridges are the same, the differential sensitivities cancel and only the sensitivity to the uniform field remains. Switches can be implemented in the power path to Figure 3A and Figure 3B To switch between different sensing element arrangements. Figure 3A and Figure 3B For the purpose of flipping the power supply of the second bridge circuit 122-2 between the first and second sensing modes (uniform field sensing mode), the magnetic field sensor circuit 300 may include a switch circuit configured to couple the lower terminal 204-2 of the second bridge circuit 122-2 to the power supply and the upper terminal 202-2 of the bridge circuit 122-2 to the ground in the first sensing mode (uniform field sensing mode). The switch circuit may also be configured to couple the lower terminal 204-2 of the second bridge circuit 122-2 to the ground and the upper terminal 202-2 of the bridge circuit 122-2 to the power supply VDDS in the second sensing mode (differential field sensing mode).

[0078] Now refer to Figure 3C Another third sensing mode is described. Figure 3C The magnetic field sensor circuit 300 and Figure 3A and Figure 3B The difference is that ground is coupled to both the upper power supply terminal 202-2 and the lower power supply terminal 204-2 of the right bridge circuit 122-2, while Figure 3A and Figure 3B In , the power supply voltage VDDS is coupled to one of the terminals 202-2 and 204-2. Figure 3C In FIG. 1 , ground is directly coupled to the sixth magnetoresistor R6 and the eighth magnetoresistor R8 , and ground is also directly coupled to the fifth magnetoresistor R5 and the seventh magnetoresistor R7 .

[0079] By applying ground to the power supply of one of the bridges 122-2, it can be easily seen that the sensing arrangement is sensitive to both differential and uniform fields.This grounding of one of the bridges 122-1, 122-2 is easily achieved.

[0080] Figure 3C The sensitivity of the architecture to the differential field can be expressed as

[0081]

[0082] Figure 3C The sensitivity of the architecture to the uniform field can be expressed as

[0083]

[0084] In order to FIG. 3A to FIG. 3C For the purpose of flipping the configuration of the magnetic field sensor circuit 200 between the two modes, the magnetic field sensor circuit 200 may include a switch circuit configured to couple both the lower terminal 204-2 and the upper terminal 202-2 of the second bridge circuit 122-2 to ground in the third sensing mode (differential field + uniform field sensing mode). The switch circuit may also be configured to couple the lower terminal 204-2 of the second bridge circuit 122-2 to ground and the upper terminal 202-2 of the bridge circuit 122-2 to a power supply VDDS in the second sensing mode (differential field sensing mode). The switch circuit may also be configured to couple the lower terminal 204-2 of the second bridge circuit 122-2 to the power supply voltage VDDS and the upper terminal 202-2 of the bridge circuit 122-2 to ground in the first sensing mode (uniform field sensing mode).

[0085] A skilled artisan having the benefit of this disclosure will recognize that Figure 3A , Figure 3B and Figure 3C The magnetic field sensor circuit 300 may appear as a standalone magnetic field sensor circuit 200, or may be combined via the above-mentioned switching circuit arrangement, which is configured to switch between different magnetic field sensor circuit arrangements.

[0086] FIG. 3A to FIG. 3C The example shows a differential output voltage (V n , V p ) of two interconnected sensing element bridges 122-1, 122-2. The differential output voltage can be further fed to one or more amplifier stages 210 or further processed. Figure 4 , where a first input terminal of the differential amplifier 210 - 1 is coupled to a first output signal (Vn), and a second input terminal of the differential amplifier 210 - 1 is coupled to a second output signal (Vp).

[0087] As previously mentioned, if a single-ended output signal is sufficient, the interconnected first bridge circuit 122 - 1 and second bridge circuit 122 - 2 may also be implemented as a half-Wheatstone bridge.

[0088] This disclosure describes an architecture with a simple technical solution for generating a differential sensor or a uniform field sensor. This can be used in a user system to provide the user with full flexibility to choose the same sensor for different applications and configure the sensor according to the desired measurement principle. On the other hand, this capability can also be used to continuously measure overlapping uniform fields and compensate for their effects in the differential measurement problem.

[0089] The present disclosure proposes an interconnected dual bridge sensing element arrangement that allows for a simple and efficient architecture of the sensor electronics incorporating the possibility of employing different operating modes on the bridge configuration.

[0090] The aspects and features described with respect to a specific one of the previous examples may also be combined with one or more of the other examples to replace equivalent or similar features of the other examples, or to additionally introduce these features into the other examples.

[0091] It should also be understood that, unless expressly stated in individual cases or required for technical reasons, the disclosure of several steps, processes, operations or functions disclosed in the specification or claims should not be interpreted as implying that these operations must depend on the described order. Therefore, the previous description does not limit the execution of several steps or functions to a specific order. In addition, in other examples, a single step, function, process or operation can include and / or be decomposed into several sub-steps, sub-functions, sub-processes or sub-operations.

[0092] If some aspects have been described with respect to a device or system, these aspects should also be understood as descriptions of the corresponding methods. For example, blocks, devices or functional aspects of a device or system may correspond to features of the corresponding methods, such as method steps. Therefore, aspects described with respect to methods should also be understood as descriptions of corresponding blocks, corresponding elements, attributes or functional features of the corresponding device or corresponding system.

[0093] The following claims are hereby incorporated into the detailed description, where each claim may stand on its own as a separate example. It should also be noted that, although in the claims, a dependent claim refers to a specific combination with one or more other claims, other examples may also include a combination of a dependent claim with the subject matter of any other dependent or independent claim. Such combinations are expressly proposed herein, unless it is stated in individual cases that a specific combination is not intended. In addition, features of a claim shall also be included with respect to any other independent claim, even if the claim is not directly qualified as dependent on the other independent claim.

Claims

1. A magnetic field sensor circuit (300), comprising: A first bridge circuit (122-1) comprising a first series connection of a first magnetoresistor (R1) and a second magnetoresistor (R2); a second bridge circuit (122-2) comprising a second series connection of a third magnetoresistor (R7) and a fourth magnetoresistor (R8), wherein a first terminal between the first magnetic resistor (R1) and the second magnetic resistor (R2) of the first bridge circuit (122-1) is coupled to a second terminal between the third magnetic resistor (R7) and the fourth magnetic resistor (R8) of the second bridge circuit (122-2), and The first terminal and the second terminal are coupled to provide a first output signal of the magnetic field sensor circuit (300).

2. The magnetic field sensor circuit (300) of claim 1, wherein the first terminal and the second terminal are short-circuited.

3. The magnetic field sensor circuit (300) according to any one of the preceding claims, wherein The first series connection of the first magnetic resistor (R1) and the second magnetic resistor (R2) is coupled between a first power supply terminal (202-1) and a first ground terminal (204-1); The second series connection of the third magnetoresistor (R7) and the fourth magnetoresistor (R8) is coupled between a second power supply terminal (202-2; 204-2) and a second ground terminal (204-2; 202-2).

4. The magnetic field sensor circuit (300) of claim 3, wherein the first power supply terminal (202-1) is coupled to the first series-connected magnetoresistors (R2) having a first reference magnetization, and the second power supply terminal (202-2) is coupled to the second series-connected magnetoresistors (R8) having a second reference magnetization, the second reference magnetization being different from the first reference magnetization.

5. The magnetic field sensor circuit (300) of claim 4, wherein the second reference magnetization is antiparallel to the first reference magnetization.

6. The magnetic field sensor circuit (300) of claim 3, wherein the first power supply terminal (202-1) is coupled to the first series-connected magnetoresistors (R2) having a first reference magnetization, and the second power supply terminal (204-2) is coupled to the second series-connected magnetoresistors (R7) having the first reference magnetization.

7. The magnetic field sensor circuit (300) according to claim 1 or 2, wherein The first series connection of the first magnetic resistor (R1) and the second magnetic resistor (R2) is coupled between a first power supply terminal (202-1) and a first ground terminal (204-1); The second series connection of the third magnetoresistor (R7) and the fourth magnetoresistor (R8) is coupled between a second ground terminal (202-2; 204-2) and a third ground terminal (204-2; 202-2).

8. A magnetic field sensor circuit (300) according to any one of the preceding claims, wherein the first series connection of the first magnetoresistors (R1) and the second magnetoresistors (R2) is coupled between a power supply and ground, wherein the magnetic field sensor circuit (300) further comprises a switching circuit configured to switch between different sensing modes by modifying a power supply of the first series connection or a power supply of the second series connection.

9. The magnetic field sensor circuit (300) according to claim 8, wherein the switch circuit is configured as: coupling the second series connection of the third and fourth magnetoresistors between the power supply and ground in a first sensing mode; In a second sensing mode, the power supply and ground terminals of the second series connection are switched compared to the first sensing mode; or In a third sensing mode, the second series connection of the third magnetoresistors and the fourth magnetoresistors is coupled between two ground terminals.

10. The magnetic field sensor circuit (300) of any one of the preceding claims, wherein the first series connection of the first magnetoresistors (R1) and the second magnetoresistors (R2) is coupled between a power supply and ground, wherein the magnetic field sensor circuit (300) further comprises: The switch circuit is configured as: coupling the second series connection of the third magnetoresistor (R7) and the fourth magnetoresistor (R8) between the power supply and ground in a first sensing mode; In a second sensing mode, the power supply and ground terminals of the second series connection are switched compared to the first sensing mode; or In a third sensing mode, the second series connection of the third magnetoresistor (R7) and the fourth magnetoresistor (R8) is coupled between two ground terminals.

11. The magnetic field sensor circuit (300) according to any one of the preceding claims, wherein The first magnetoresistor (R1) of the first bridge circuit comprises a first reference magnetization, The second magnetoresistor (R2) of the first bridge circuit comprises a second reference magnetization different from the first reference magnetization, The third magnetoresistor (R7) of the second bridge circuit comprises the second reference magnetization, The fourth magnetoresistor (R8) of the second bridge circuit comprises the first reference magnetization.

12. The magnetic field sensor circuit (300) of claim 11, wherein the second reference magnetization is antiparallel to the first reference magnetization.

13. The magnetic field sensor circuit (300) according to any one of the preceding claims, wherein The first bridge circuit (122-1) comprises a third series connection of a fifth magnetoresistor and a sixth magnetoresistor, the third series connection being connected in parallel with the first series connection; The second bridge circuit (122-2) comprises a fourth series connection of a seventh magnetoresistor and an eighth magnetoresistor, the fourth series connection being connected in parallel with the second series connection; wherein a third terminal between the fifth and sixth magneto-resistors of the first bridge circuit is coupled to a fourth terminal between the seventh and eighth magneto-resistors of the second bridge circuit, and The third terminal and the fourth terminal coupled therein provide a second output signal of the magnetic field sensor circuit.

14. The magnetic field sensor circuit (300) of claim 13, wherein the third terminal and the fourth terminal are short-circuited.

15. The magnetic field sensor circuit (300) according to claims 11 and 13, wherein The fifth magnetoresistor of the first bridge circuit comprises the second reference magnetization, The sixth magnetoresistor of the first bridge circuit comprises the first reference magnetization, The seventh magnetoresistor of the second bridge circuit comprises the first reference magnetization, and The eighth magnetoresistor of the second bridge circuit comprises the second reference magnetization.

16. The magnetic field sensor circuit (300) according to any one of claims 13 to 15, further comprising: A differential amplifier (210) wherein A first input terminal of the differential amplifier (210) is coupled to the first output signal, and A second input terminal of the differential amplifier (210) is coupled to the second output signal.

17. The magnetic field sensor circuit (300) according to any one of the preceding claims, wherein the magnetoresistors of the first bridge circuit (122-1) and the second bridge circuit (122-2) are giant magnetoresistors (GMR) or tunnel magnetoresistors (TMR).

18. A method for measuring a magnetic field, comprising: providing a first bridge circuit comprising a first series connection of a first magnetoresistor and a second magnetoresistor; providing a second bridge circuit comprising a second series connection of a third magnetoresistor and a fourth magnetoresistor, coupling a first terminal between the first and second magneto-resistors of the first bridge circuit to a second terminal between the third and fourth magneto-resistors of the second bridge circuit, and An output signal of the magnetic field sensor circuit is provided at the coupled first and second terminals.

19. The method according to claim 18, wherein the first bridge circuit comprising a third series connection of a fifth magnetoresistor and a sixth magnetoresistor, the third series connection being connected in parallel with the first series connection; the second bridge circuit comprising a fourth series connection of a seventh magnetoresistor and an eighth magnetoresistor, the fourth series connection being connected in parallel with the second series connection; coupling a third terminal between the fifth and sixth magneto-resistors of the first bridge circuit to a fourth terminal between the seventh and eighth magneto-resistors of the second bridge circuit; and A second output signal of the magnetic field sensor circuit is provided at the coupled third terminal and the fourth terminal.

20. The method according to claim 18 or 19, comprising: coupling the first series connection of the first magnetoresistors and the second magnetoresistors between a power source and ground; as well as Switching between different sensing modes is performed by modifying the first series-connected power source or the second series-connected power source.

21. The method of claim 20, wherein switching comprises: coupling the second series connection of the third and fourth magnetoresistors between the power supply and ground in a first sensing mode; In a second sensing mode, compared to the first sensing mode, switching the terminals of the power supply and the ground of the second series connection; or In a third sensing mode, the second series connection of the third magnetoresistors and the fourth magnetoresistors is coupled between two ground terminals.

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