Magnetic field current sensor for reducing stray magnetic fields

Abstract

In one aspect, a magnetic field current sensor includes an annihilation detector. The annihilation detector includes an annihilation bridge including a magnetoresistive element. The annihilation detector further includes a current bridge including at least two of the magnetoresistive elements, a first comparator configured to compare output signals from the annihilation bridge, and a second comparator configured to compare output signals from the current bridge. An output of the annihilation detector uses at least one of an output signal of the first comparator and an output signal of the second comparator to indicate whether annihilation is present in one or more of the magnetoresistive elements.

Description

Background Art

[0001] Magnetic field sensors are used in a variety of applications, including but not limited to: angle sensors, which sense the directional angle of a magnetic field; current sensors, which sense the magnetic field generated by the current carried by a current-carrying conductor; magnetic switches, which sense the approach of a ferromagnetic object; rotation detectors, which sense the magnetic domains of passing ferromagnetic items, such as ring magnets or ferromagnetic targets (e.g., gear teeth), in which the magnetic field sensor is used in conjunction with a reverse-biased or other magnet; magnetic field sensors, which sense the magnetic field density of a magnetic field; linear sensors, which sense the position of a ferromagnetic target; and the like.

[0002] The magnetic field sensor may include a magnetic field sensing element. A magnetic field sensing element is used to describe a variety of electronic components that can sense a magnetic field. The magnetic field sensing element may be, but is not limited to, a Hall effect element, a magnetoresistive element, or a magnetic transistor. As is well known, there are different types of Hall effect elements, such as planar Hall elements, vertical Hall elements, and circular vertical Hall (CVH) elements. There are different types of magnetoresistive elements, such as semiconductor magnetoresistive elements such as indium antimonide (InSb), giant magnetoresistive (GMR) elements such as spin valves, anisotropic magnetoresistive elements (AMR), tunnel magnetoresistive (TMR) elements, and magnetic tunnel junctions (MTJs). The magnetic field sensing element may be a single element, or alternatively, may include two or more magnetic field sensing elements arranged in a variety of configurations, such as a half bridge or a full (Wheatstone) bridge. Depending on the device type and other application requirements, the magnetic field sensing element may be a device made of a type IV semiconductor material such as silicon (Si) or germanium (Ge), a type III-V semiconductor material such as gallium arsenide (GaAs), or an indium compound such as indium antimonide (InSb). Summary of the invention

[0003] In one aspect, a magnetic field current sensor includes an annihilation detector. The annihilation detector includes an annihilation bridge including magnetoresistive elements. The annihilation detector also includes a current bridge, a first comparator, and a second comparator, wherein the current bridge includes at least two magnetoresistive elements, the first comparator is configured to compare output signals from the annihilation bridge, and the second comparator is configured to compare output signals from the current bridge. The output of the annihilation detector indicates whether annihilation exists in one or more magnetoresistive elements using at least one of the output signal of the first comparator and the output signal of the second comparator.

[0004] The aforementioned aspects may include one or more of the following features. The annihilation detector may further include an OR circuit configured to receive an output signal from the first comparator and output information from the second comparator, and the OR circuit is configured to provide an output signal of the annihilation detector, the output signal indicating whether the current sensor operates within a linear range. The magnetoresistive element may include a first tunnel magnetoresistive (TMR) element, a second TMR element, a third TMR element, and a fourth TMR element. The first TMR element, the second TMR element, the third TMR element, and the fourth TMR element may each include a free layer forming a magnetic disk. Each of the first TMR element, the second TMR element, the third TMR element, and the fourth TMR element may have a reference direction along a first direction. The first TMR element may be a part of a first branch of an annihilation bridge, the second TMR element may be a part of a second branch of an annihilation bridge, the third TMR element may be a part of a first branch of an annihilation bridge, and the fourth TMR element may be a part of a second branch of an annihilation bridge. The first TMR element and the second TMR element may be located on top of a single-turn conductor. The third TMR element and the fourth TMR element may not contact the single-turn conductor located between the first TMR element and the second TMR element. The distance from the first TMR element to the second TMR element may be equal to the distance from the third TMR element to the fourth TMR element. The third TMR element may be interlaced with the fourth TMR element. The first TMR element, the second TMR element, the third TMR element and the fourth TMR element may be located at least on the same plane. The first TMR element may be part of the first branch of the current bridge, the second TMR element may be part of the first branch of the current bridge, the third TMR element may be part of the second branch of the current bridge, and the fourth TMR element may be part of the second branch of the current bridge. The first TMR element, the second TMR element, the third TMR element and the fourth TMR element may be located on top of the double-turn conductor. The distance from the first TMR element to the second TMR element may be equal to the distance from the third TMR element to the fourth TMR element. The second TMR element may be interlaced with the third TMR element. The first TMR element, the second TMR element, the third TMR element and the fourth TMR element may be located on the same plane. The first TMR element may be part of a first branch of the annihilation bridge, the second TMR element may be part of the first branch of the annihilation bridge, the third TMR element may be part of a second branch of the annihilation bridge, and the fourth TMR element may be part of the second branch of the annihilation bridge. The first TMR element may be formed in a first column having a first diameter, the second TMR element may be formed in a second column having the first diameter, the third TMR element may be formed in a third column having a second diameter different from the first diameter, and the fourth TMR element may be formed in a fourth column having the second diameter.The first diameter can be less than the second diameter. The first TMR element, the second TMR element, the third TMR element and the fourth TMR element can be located on the top of the single-turn conductor. The first TMR element and the third TMR element are located on the top of one end of the conductor, and the second TMR element and the fourth TMR element are located on the top of the other end of the conductor. The distance between the first TMR element and the third TMR element can be approximately 20 microns, and the distance between the first TMR element and the second TMR element can be approximately 400 microns. The first bridge may include a first TMR element and a second TMR element forming a first branch of the first bridge, wherein the first TMR element is closer to the first current source in electrical series than the second TMR element, the first bridge may further include a first TMR element and a second TMR element forming a second branch of the first bridge, wherein the second TMR element is closer to the first current source in electrical series than the first TMR element, the second bridge may include a third TMR element and a fourth TMR element forming the first branch of the second bridge, wherein the third TMR element is closer to the second current source in electrical series than the fourth TMR element, the second bridge may further include a third TMR element and a fourth TMR element forming the second branch of the second bridge, wherein the fourth TMR element is closer to the second current source in electrical series than the third TMR element, and one of the first bridge and the second bridge is an annihilation bridge. The other of the first bridge and the second bridge may be a current bridge. The first TMR element, the second TMR element, the third TMR element, and the fourth TMR element may be located on top of a single-turn conductor. The first TMR element and the fourth TMR element may be located on top of one end of the conductor, and the second TMR element and the third TMR element may be located on top of the other end of the conductor. The first TMR element and the third TMR element may be located on a first axis, the second TMR element and the fourth TMR element may be located on a second axis, and the first axis is parallel to the second axis. The first bridge may include a first branch and a second branch; in the first branch, the first TMR element may be closer to the first current source in terms of electrical series connection than the second TMR element, the second TMR element may be closer to the third current source in terms of electrical series connection than the third TMR element, and the third TMR element may be closer to the first current source in terms of electrical series connection than the fourth TMR element; and in the second branch, the third TMR element may be closer to the first current source in terms of electrical series connection than the fourth TMR element, the fourth TMR element may be closer to the first current source in terms of electrical series connection than the first TMR element, and the first TMR element may be closer to the first current source in terms of electrical series connection than the second TMR element; and the first bridge may be one of an annihilation bridge and a current bridge.

[0005] On the other hand, a magnetic field current sensor includes a conductor and a magnetic field sensing element. The magnetic field sensing element includes a first magnetic field sensing element that generates a first signal, a second magnetic field sensing element that generates a second signal, a third magnetic field sensing element that generates a third signal, and a fourth magnetic field sensing element that generates a fourth signal. The magnetic field current sensor also includes a circuit that generates a signal indicating twice the second signal minus the first signal and minus the fourth signal. The second magnetic field sensing element is interlaced with the third magnetic field sensing element. The second signal and the third signal are substantially equal. The first magnetic field sensing element, the second magnetic field sensing element, the third magnetic field sensing element, and the fourth magnetic field sensing element are located in a first plane, and the distance between the first magnetic field sensing element and the second magnetic field sensing element is equal to the distance between the second magnetic field sensing element and the fourth magnetic field sensing element.

[0006] In another aspect, the magnetic field current sensor includes an annihilation detector including magnetoresistive elements each having a magnetic vortex. An output of the annihilation detector indicates whether annihilation exists in one or more of the magnetoresistive elements. This aspect may include a feature wherein the annihilation detector may include an annihilation bridge including the magnetoresistive elements and a current bridge including at least two of the magnetoresistive elements.

[0007] In yet another aspect, the annihilation detector includes magnetoresistive elements, and the output of the annihilation detector indicates whether annihilation is present in one or more of the magnetoresistive elements. This aspect may include a feature wherein the annihilation detector may include an annihilation bridge including magnetoresistive elements and a current bridge including at least two magnetoresistive elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing features may be more fully understood through the following description of the accompanying drawings. The accompanying drawings assist in explaining and understanding the disclosed technology. Since it is generally impractical or impossible to illustrate and describe every possible embodiment, the accompanying drawings provided depict one or more illustrative embodiments. Therefore, the accompanying drawings are not intended to limit the scope of the broad concepts, systems and techniques described herein. The same numbers in the figures represent the same elements.

[0009] FIG. 1A is a block diagram of an example of a tunnel magnetoresistive (TMR) element;

[0010] 1B is a simplified diagram of an example of a free layer having a magnetic vortex including a core located at the center of the free layer;

[0011] Figure 1C is a simplified diagram of an example of a free layer having a uniform magnetization direction;

[0012] Figure 1D is a simplified diagram of an example of a free layer subjected to an external magnetic field that causes a magnetic vortex to swirl away from the center of the free layer;

[0013] Figure 1E is a simplified diagram of an example of a free layer that is influenced by an external magnetic field to have a nearly uniform magnetization direction;

[0014] Figure 1F is a simplified diagram of another example of a free layer subjected to an external magnetic field that causes a magnetic vortex to swirl away from the center of the free layer;

[0015] Figure 1G is a schematic diagram of another exemplary free layer, the exemplary free layer being influenced by an external magnetic field to have a nearly uniform magnetization direction;

[0016] Figure 2 is a graph of a response signal versus a magnetic field for a tunnel magnetoresistance (TMR) element having a magnetic vortex in a free layer;

[0017] Figure 3 is a block diagram of an example of an annihilation detector circuit;

[0018] Figure 4A and Figure 4B is a graph depicting an example of the output of an annihilation detector;

[0019] Figure 5A is a simplified diagram of an example of a current sensor configuration including a conductor and a TMR element having a magnetic vortex;

[0020] Figure 5B is used Figure 5A Example of an annihilation bridge of a TMR element in FIG.

[0021] Figure 5C is used Figure 5A Example of a current bridge with TMR elements in ;

[0022] Fig. 6A is a simplified diagram of an example of a current sensor configuration including a conductor and a TMR element having two different column diameters and having a magnetic vortex;

[0023] Figure 6B Is for use with smaller diameter columns Fig. 6A A simplified diagram of an example of a bridge of TMR elements in FIG.

[0024] Figure 6C Is used for columns with larger diameters Fig. 6A A simplified diagram of an example of a bridge of TMR elements in FIG.

[0025] Fig.6D is used for Figure 6B and Figure 6C An example graph of the output of the bridge in FIG.

[0026] Fig. 7A is an example of a current sensor configuration with a conductor and a TMR element having a magnetic vortex;

[0027] Figure 7B is used Fig. 7A Example of a current bridge with TMR elements;

[0028] Fig. 8A is a simplified diagram of another example of a current sensor configuration including a conductor and a TMR element having a magnetic vortex;

[0029] Figure 8B is used Fig. 8A A simplified diagram of the bridge of TMR elements in FIG.

[0030] Figure 8C is used Fig. 8A A simplified diagram of the bridge of TMR elements in FIG.

[0031] Fig. 9 is depicted due to the use of a conventional differential current sensor configuration and Fig. 8A A graph of a residual signal caused by adjacent current lines of a current sensor configuration;

[0032] Fig. 10A is an example of a current sensor configuration including a conductor and a vertical Hall element;

[0033] Fig. 10B It is used to adjust the Fig. 10A An example of a circuit for a vertical Hall element signal;

[0034] Fig.11A is an example of a current sensor configuration including a conductor and a planar Hall element; and

[0035] Fig. 11B It is used to adjust the Fig.11A Example of a circuit for the signal of a planar Hall element. DETAILED DESCRIPTION

[0036] This article describes techniques for making current sensors that reduce the effects of stray magnetic fields. In one example, the current sensor includes an annihilation detector circuit and includes a magnetoresistive element having a magnetic vortex in a free layer. In another example, the current sensor includes magnetoresistive elements having at least two different column diameters and having a magnetic vortex in the free layer. In another example, the current sensor includes a magnetoresistive element having a magnetic vortex in the free layer, and has some magnetoresistive elements whose reference directions are 180° with other magnetoresistive elements. In another example, magnetic field sensing elements (e.g., planar Hall elements, vertical Hall elements, and magnetoresistive elements) can be used in current sensors in certain configurations to reduce gradient stray magnetic field effects and common-mode stray magnetic field effects.

[0037] Referring to FIG. 1A , an illustrative TMR element 100 may have a stack 102 of layers 106, 110, 114, 118, 122, 126, 128, 132 representing one column of a multi-column TMR element. Typically, layer 106 is a seed layer (e.g., a copper nickel (CuN) layer), wherein layer 110 is located on seed layer 106. Layer 110 includes, for example, platinum manganese (PtMn) or iridium manganese (IrMn). Layer 114 is located on layer 110, and layer 118 is located on layer 114. In one example, layer 114 includes cobalt iron (CoFe), and layer 118 is a spacer layer and includes ruthenium (Ru). On layer 118, a magnesium oxide (MgO) layer 126 is sandwiched between two cobalt iron boron (CoFeB) layers 122, 128. A cap layer 132 (e.g., tantalum (Ta)) is located on CoFeB layer 128. Layer 114 is a single pinned layer that is magnetically coupled to layer 110. The physical mechanism that couples layers 110 and 114 together is sometimes referred to as exchange bias.

[0038] The free layer 130 includes the CoFeB layer 128. In some examples, the free layer 130 may include an additional nickel iron (NiFe) layer (not shown) and a tantalum thin layer (not shown) between the CoFeB layer 128 and the NiFe layer.

[0039] 1B, the TMR formed as a column may include a free layer 160 having a magnetic vortex. For example, the magnetic vortex has a magnetization direction (e.g., magnetization direction 164a, magnetization direction 164b, magnetization direction 164c, magnetization direction 164d) surrounding the free layer 160. The free layer 160 is a magnetic disk. The angle of the magnetization direction 164a relative to the surface of the free layer 160 is about 0° at the outer edge of the free layer 160.

[0040] The magnetic vortex has a core 170 (which is sometimes referred to as a "magnetic vortex core"). The closer to the center of the core 170, the magnetization direction begins to become more and more non-planar. That is, the angle of the magnetization direction relative to the surface of the free layer 160 increases as the magnetization direction approaches the center of the core 170. For example, the angle of the magnetization direction 164b relative to the surface of the free layer 160 is greater than the angle of the magnetization direction 164a relative to the surface of the free layer 160, the angle of the magnetization direction 164c relative to the surface of the free layer 160 is greater than the angle of the magnetization direction 164b relative to the surface of the free layer 160, and the angle of the magnetization direction 164d relative to the surface of the free layer 160 is greater than the angle of the magnetization direction 164c relative to the surface of the free layer 160.

[0041] Exchange energy and demagnetization energy are two key phenomena in magnetic disks. Exchange energy increases energy consumption when magnetization is non-uniform across the magnetic material of the disk, while demagnetization energy increases consumption when the magnetization direction points to the outside of the disk. Exchange energy is a volume effect term, while demagnetization energy is an edge effect term.

[0042] refer to Figure 1C , when the disk of the free layer 160 has a large diameter and is thin, the magnetization direction (e.g., magnetization direction 164e) tends to be uniform and is in the plane of the free layer 160 across the disk. When the magnetization direction points to the outside of the disk, there is a consumption of demagnetization energy. This energy consumption is located on the edge of the disk. Therefore, if the diameter of the disk is large enough, the volume effect (i.e., exchange energy) is more important than the edge effect (i.e., demagnetization energy). Therefore, it is more biased to make the magnetization uniform in the plane.

[0043] Referring back to FIG. 1B , if the diameter and thickness of the disk are not as large as Figure 1C 1B , the size of the core 170 is exaggerated relative to the free layer 160 to make it easier to observe and describe in this article.

[0044] refer to Figure 1D and Figure 1E , when an external magnetic field 180 is applied to the free layer 160 including the magnetic vortex, the core 170 of the magnetic vortex moves to favor magnetization along the applied magnetic field 180. However, if the applied magnetic field 180 is too large, the core 170 is pushed out of the disk and the magnetization direction (e.g., magnetization direction 164e) in the disk becomes almost uniform. This is called vortex annihilation. Before the vortex core can nucleate again within the disk, the external magnetic field 180 must be reduced to the nucleation magnetic field level, as shown in the reference Figure 2 described.

[0045] refer to Figure 1F and Figure 1G Likewise, when an external magnetic field 190 (opposite to the magnetic field 180) is applied to the free layer 160 including the magnetic vortex, the core 170 of the magnetic vortex moves to facilitate magnetization along the applied magnetic field 190. However, if the applied magnetic field 180 is too large, the core 170 is pushed out of the disk, and the magnetization direction (e.g., magnetization direction 164f) in the disk becomes uniform.

[0046] refer to Figure 2 , graph 200 depicts an example of a TMR signal response to a detected change in magnetic field. The nucleation field is given by H N1 and H N2 The annihilation field is represented by H AN1 and H AN2 Indicates that the TMR signal response 202 is in H N1 and H N2 It is linear between.

[0047] However, in H AN1 and H N1 Between and in H N2 and H AN2 Between H and , the TMR signal response 202 may be linear or saturated. N2 and H AN2 The TMR signal response 202 between is linear along portion 214a and saturated along portion 218a, and H N1 and H AN1 The TMR signal response 202 is linear along portion 214b and saturated along portion 218b.

[0048] When the TMR magnetic vortex is exposed to higher than H AN1 or H AN2 The magnetic field of H is extinguished (ie, the vortex is annihilated) and the TMR signal response 202 does not return to H, respectively. N1 or H N2 When , saturation occurs. An annihilation detector as described herein (e.g., annihilation detector 300 ( Figure 3 )) can determine whether there is an annihilation vortex. In the case of an annihilation vortex, it is not possible to use a value exceeding H N1 and H N2 However, if the annihilation detector does not detect an annihilation vortex, the TMR signal response 202 outside of H can be used. AN1 and H N1 Between and in H N2 and H AN2 The TMR signal response 202 between.

[0049] Point 252a on the TMR signal response 202 corresponds to the free layer 160 in FIG. 1B. Point 252b on the TMR signal response 202 corresponds to Figure 1D The free layer 160 in the TMR signal response 202 corresponds to the point 252c. Figure 1E The point 252d on the TMR signal response 202 corresponds to Figure 1F The free layer 160 in FIG. 1 and the point 252e on the TMR signal response 202 corresponds to Figure 1GThe free layer 160 in FIG.

[0050] refer to Figure 3 An example of an annihilation detector that can detect an annihilation vortex is the annihilation detector 300. The annihilation detector 300 includes an annihilation bridge 302, offset trimming circuits 306a, 306b, rectifiers 310a, 310b, comparators 314a, 314b, an OR circuit, and a current bridge 324.

[0051] The output of the annihilation bridge 302 is fine-tuned by the offset trimming circuit 306a and then rectified by the rectifier 310a. The comparator 314a compares the rectified signal from the rectifier 310a with a first threshold. In one example, if the rectified signal from the rectifier 310a is higher than the first threshold, the vortex is annihilated. In one example, the first threshold is derived from a hysteresis curve.

[0052] The output of the current bridge 324 is fine-tuned by the offset trimming circuit 306b and then rectified by the rectifier 310b. The comparator 314b compares the rectified signal from the rectifier 310b with the second threshold. In one example, if the rectified signal from the rectifier 310b is higher than the second threshold, the vortex is annihilated. In one example, the second threshold may be a value corresponding to H AN1 and / or H AN2 of current.

[0053] The outputs of the comparators 314a, 314b are sent to an OR circuit 318. The OR circuit performs a logical "OR" function on the outputs of the comparators 314a, 314b to generate an output signal 350, which is the output of the annihilation detector 300.

[0054] refer to Figure 4A and Figure 4B , the curves 400a and 400b are different stray magnetic fields H SF The output signal is 350( Figure 3 ). The X-axis of each pair of graphs 400a, 400b is the magnetic field (i.e., the signal of interest) generated from a conductor (e.g., conductor 506), and the Y-axis of each pair of graphs 400a, 400b is the rectified output of the annihilation detector 300 (expressed in arbitrary units). There are two pairs of graphs 400a, 400b because annihilation of vortices can occur toward a negative magnetic field (graph 400b) or toward a positive magnetic field (graph 400a). Curves 412a, 412b represent a stray magnetic field of 40 Oersted, curves 414a, 414b represent a stray magnetic field of 8 Oersted, and curves 412a and 412b represent a stray magnetic field of 40 Oersted.

[0055] refer to Figure 5A, the current sensor configuration 500 includes TMR elements (eg, TMR element 502a, TMR element 502b, TMR element 502c, and TMR element 502d) and a single turn conductor 506. The TMR elements 502a, 502b, 502c, 502d each include at least one free layer having a magnetic vortex.

[0056] Each of TMR elements 502a, 502b, 502c, 502d includes a reference direction that is the same as the other TMR elements. The reference direction is the direction in which the magnetoresistive element is most sensitive to changes in the magnetic field. For example, for changes in the magnetic field in the reference direction, the resistance of the magnetoresistive element changes the most. TMR element 502a has a reference direction 510a, TMR element 502b has a reference direction 510b, TMR element 502c has a reference direction 510c, and TMR element 502d has a reference direction 510d.

[0057] TMR elements 502a, 502b are located on top of conductor 506, and TMR elements 501c, 502d are placed between TMR elements 502a, 502d and do not contact conductor 506. In one example, TMR elements 502c and TMR elements 502d can be staggered. In one example, TMR elements 502a, 502b can be spaced apart from conductor 506 by a distance of 50 microns to 200 microns.

[0058] TMR elements 502a, 502b, 502c, 502d are located in a manner extending in and out of Figure 5A During operation, current 516 is applied to one end of conductor 506 to form an Oersted field.

[0059] Since the TMR elements 502c, 502d are placed in the center of the single-turn conductor 506, the TMR elements 502c, 502d are only exposed to the stray magnetic field H. SF , while the TMR elements 502a, 502b are exposed to a stray magnetic field H SF and the Oersted field caused by the current I (eg, current 516) passing through the conductor 506. In one example, the TMR element 502a detects the magnetic field H A , TMR element 502b detects magnetic field H B , TMR element 502c detects magnetic field H C , and the TMR element 502d detects the magnetic field H D , so that:

[0060] H A =H SF +α·I,

[0061] H B =HSF -α·I,

[0062] H C =H D =H SF ,

[0063] Where α is the conversion factor from current to magnetic field.

[0064] refer to Figure 5B , an example of the annihilation bridge 302 is the annihilation bridge 302'. The output of the bridge 302' is the difference between the signal measured at the node A and the signal measured at the node B.

[0065] In one example, for the current source ICC1, the signal measured at the node A and the signal measured at the node B are both voltage signals. In another example, if the current source ICC1 is replaced with a fixed voltage source and the voltage is fixed at the nodes A and B, the signal measured at the node A and the signal measured at the node B are both current signals.

[0066] TMR element 502a and TMR element 501c are electrically connected in series to form a first branch of bridge 302'. TMR element 502a is electrically closer to current source ICC1 than TMR element 502c.

[0067] TMR element 502b and TMR element 501d are electrically connected in series to form a second branch of bridge 302'. TMR element 502d is electrically closer to current source ICC1 than TMR element 502b.

[0068] By connecting TMR elements 502a, 502b, 502c, 502d in a bridge, the net magnetic field caused by the stray field and the Oersted field can be obtained:

[0069] H C +H D –(H A +H B )=H SF +H SF –(H SF +α·I+H SF -α·I)=0.

[0070] The signal is zero regardless of current or stray magnetic field, unless the vortex is annihilated because the magnetic field on one element is higher than H AN .therefore, Figure 5A The configuration in reduces stray field signals unless one or more of the TMR elements 502a, 502b, 502c, 502d no longer has a linear response to the magnetic field (ie, has one or more vortices that are annihilated).

[0071] refer to Figure 5C , an example of the current bridge 324 is the current bridge 324 ′. The output of the bridge 324 ′ is the difference between the signal measured at the node C and the signal measured at the node D.

[0072] In one example, for the current source ICC2, the signal measured at the node C and the signal measured at the node D are both voltage signals. In another example, if the current source ICC2 is replaced with a fixed voltage source and the voltage is fixed at the nodes C and D, the signal measured at the node C and the signal measured at the node D are both current signals.

[0073] TMR element 502a and TMR element 502b are electrically connected in series to form a first branch of bridge 324'. TMR element 502a is electrically closer to current source ICC2 in series than TMR element 502b.

[0074] TMR element 502b and TMR element 502a are electrically connected in series to form a second branch of bridge 324'. TMR element 502b is electrically closer to current source ICC2 in series than TMR element 502a.

[0075] refer to Fig. 6A , the current sensor configuration 600 includes TMR elements (eg, TMR element 602a, TMR element 602b, TMR element 604a, and TMR element 604b) and a single turn conductor 606. The TMR elements 602a, 602b, 604a, 604b each include a free layer having a magnetic vortex.

[0076] TMR elements 602a, 602b are formed into pillars having a smaller diameter than the pillars of TMR elements 604a, 604b. In one example, TMR elements 602a, 602b are formed into pillars having a diameter of 2 microns, while TMR elements 604a, 604b are formed into pillars having a diameter of 3 microns.

[0077] Each of TMR elements 602a, 602b, 604a, 604b includes the same reference direction as the other TMR elements. For example, TMR element 602a has a reference direction 608a, TMR element 602b has a reference direction 608b, TMR element 604a has a reference direction 610a, and TMR element 604b has a reference direction 610b.

[0078] TMR elements 602a, 604a are located on top of one end of conductor 606, while TMR elements 602b, 604b are located on top of the other end of conductor 606. In one example, TMR elements 602a, 602b, 604a, 604b may be spaced apart from conductor 606 by a distance of 50 microns to 200 microns.

[0079] TMR elements 602a, 602b are located on axis 612a, and TMR elements 604a, 604b are located on axis 612b. In one example, axis 612a is parallel to axis 612b. During operation, current 616 is applied to one end of conductor 606.

[0080] refer to Figure 6B The output of the bridge 614a is the difference between the signal measured at the node E and the signal measured at the node F.

[0081] In one example, for the current source ICC3, the signal measured at the node E and the signal measured at the node F are both voltage signals. In another example, if the current source ICC3 is replaced with a fixed voltage source and the voltage is fixed at the nodes E and F, the signal measured at the node E and the signal measured at the node F are both current signals.

[0082] TMR element 602a and TMR element 601b are electrically connected in series to form a first branch of bridge 614a. TMR element 602a is electrically closer to current source ICC3 than TMR element 602b.

[0083] TMR element 602b and TMR element 602a are electrically connected in series to form a second branch of bridge 614a. TMR element 602b is electrically closer to current source ICC3 in series than TMR element 602a.

[0084] The bridge 614b includes TMR elements 604a, 604b. The output of the bridge 614b is the difference between the signal measured at the node G and the signal measured at the node H.

[0085] In one example, for the current source ICC4, the signal measured at the node G and the signal measured at the node H are both voltage signals. In another example, if the current source ICC4 is replaced with a fixed voltage source and the voltage is fixed at the nodes G and H, the signal measured at the node G and the signal measured at the node H are both current signals.

[0086] TMR element 604a and TMR element 604b are electrically connected in series to form a first branch of bridge 614a. TMR element 604a is electrically closer to current source ICC4 in series than TMR element 604b.

[0087] TMR element 604b and TMR element 604a are electrically connected in series to form a second branch of bridge 614b. TMR element 604b is electrically closer to current source ICC4 in series than TMR element 604a.

[0088] In one example, bridge 614a and bridge 614b are examples of current bridges, each having a different sensitivity to magnetic fields and having different internal ranges. Bridge 614a has the largest linear range and is used as an example of current bridge 324 ( Figure 3 ).

[0089] refer to Fig.6D , graph 650 depicts the relationship between the bridge output and the magnetic field. For example, curve 652 is the bridge 614a ( Figure 6B ) and the relationship between the output and the magnetic field change, and curve 654 is the relationship between the output of bridge 614b ( Figure 6B ) output and magnetic field change. Figure 5B )) can be used to detect whether bridge 614a is annihilated. Bridge 614a provides a measurement of the magnetic field. Based on this measurement, it is known whether bridge 614b is annihilated.

[0090] refer to Fig. 7A , the current sensor configuration 700 includes TMR elements (e.g., TMR element 702a, TMR element 702b, TMR element 704a, and TMR element 704b) and a single turn conductor 706. TMR elements 702a, 702b, 704a, 704b each include a free layer having a magnetic vortex. The current sensor configuration 700 can be used to account for temperature gradients in an integrated circuit, where some TMR elements are exposed to larger temperature gradients than other TMR elements.

[0091] Both TMR elements 702a and 704a include a reference direction in the same direction. For example, TMR element 702a has a reference direction 708a, and TMR element 704a has a reference direction 710a along the same direction.

[0092] TMR elements 702b, 704b both include reference directions in the same direction. For example, TMR element 704a has reference direction 708b, and TMR element 704b has reference direction 710b along that direction. Reference directions 708b, 710b are in directions that differ by 180° from reference directions 708a, 710a.

[0093] TMR elements 702a, 704b are located on top of one end of conductor 706, while TMR elements 702b, 704a are located on top of the other end of conductor 706. In one example, TMR elements 702a, 702b, 704a, 704b may be spaced apart from conductor 706 by a distance of 50 microns to 200 microns.

[0094] In one example, TMR element 702a and TMR element 704b are spaced apart by no less than 20 microns ± 5 microns. In one example, TMR element 704a and TMR element 702b are typically spaced apart by 400 microns ± 100 microns. During operation, current 716 is applied to one end of conductor 706.

[0095] In one example, TMR elements 702a, 704a can be located on axis 712a, and TMR elements 702b, 704b can be located on axis 712b. In one example, axis 712a is parallel to axis 712b.

[0096] Reference Figure 7B The current bridge 714 includes TMR elements 702a, 702b, 704a, 704b. The output of the bridge 714 is the difference between the signal measured at the node I and the signal measured at the node J.

[0097] In one example, for the current source ICC5, the signal measured at the node I and the signal measured at the node J are both voltage signals. In another example, if the current source ICC5 is replaced with a fixed voltage source and the voltage is fixed at the nodes I and J, the signal measured at the node I and the signal measured at the node J are both current signals.

[0098] TMR elements 702a, 702b, 704a, 704b are electrically connected in series to form a first branch of bridge 714. In one example, TMR element 702a is closer to current source ICC5 in electrical series than TMR element 702b, TMR element 702b is closer to current source ICC5 in electrical series than TMR element 704a, and TMR element 704a is closer to current source ICC5 in electrical series than TMR element 704b.

[0099] TMR elements 704a, 704b, 702a, 702b are electrically connected in series to form a second branch of bridge 714. In one example, TMR element 704a is closer to current source ICC5 in electrical series than TMR element 704b, TMR element 704b is closer to current source ICC5 in electrical series than TMR element 702a, and TMR element 702a is closer to current source ICC5 in electrical series than TMR element 702b.

[0100] Reference Fig. 8A and Figure 8B , the current sensor configuration 800 includes TMR elements (eg, TMR element 802a, TMR element 802b, TMR element 802c, and TMR element 802d) and a double-turn conductor 806. The TMR elements 802a, 802b, 802c, 802d each include a free layer having a magnetic vortex.

[0101] Each of TMR elements 802a, 802b, 802c, 802d includes a reference direction that is the same as the other TMR elements. For example, TMR element 802a has a reference direction 810a, TMR element 802b has a reference direction 810b, TMR element 802c has a reference direction 810c, and TMR element 802d has a reference direction 810d.

[0102] TMR elements 802a, 802b, 802c, 802d are located on top of conductor 806. TMR elements 802a, 802b, 802c, 802d are located in the XY plane. During operation, current 816 is applied to one end of conductor 806. In one example, TMR elements 802a, 802b, 802c, 802d can be spaced apart from conductor 606 by a distance of 50 microns to 200 microns.

[0103] TMR elements 802b are staggered with TMR elements 802c. The distance between TMR elements 802a and 802b is approximately the same as the distance between TMR elements 802b and 802d.

[0104] The bridge 814 includes TMR elements 802a, 802b, 802c, 802d. The output of the bridge 814 is the difference between the signal measured at the node K and the signal measured at the node L. In one example, the bridge 814 is a current bridge 324 ( Figure 3 ) example.

[0105] In one example, for the current source ICC6, the signal measured at the node K and the signal measured at the node L are both voltage signals. In another example, if the current source ICC6 is replaced with a fixed voltage source and the voltage is fixed at the nodes K and L, the signal measured at the node K and the signal measured at the node L are both current signals.

[0106] TMR element 802a and TMR element 802b are electrically connected in series to form a first branch of bridge 814. TMR element 802a is electrically closer in series to current source ICC6 than TMR element 802b.

[0107] TMR element 802c and TMR element 802d are electrically connected in series to form a second branch of bridge 814. TMR element 802c is electrically closer in series to current source ICC6 than TMR element 802d.

[0108] Reference Figure 8C , the bridge 816 includes TMR elements 802a, 802c. The output of the bridge 816 is the difference between the signal measured at node X and the signal measured at node Y. In one example, the bridge 816 is a current bridge 324 ( Figure 3 ) example.

[0109] In one example, for current source ICC22, the signal measured at node X and the signal measured at node Y are both voltage signals. In another example, if current source ICC22 is replaced with a fixed voltage source and the voltage is fixed at node X and node Y, the signal measured at node X and the signal measured at node Y are both current signals. TMR element 802a and TMR element 802c are electrically connected in series to form a first branch of bridge 816. TMR element 802a is closer to current source ICC22 in terms of electrical series connection than TMR element 802c.

[0110] TMR element 802c and TMR element 802a are electrically connected in series to form a second branch of bridge 816. TMR element 802c is electrically closer to current source ICC22 in series than TMR element 802a.

[0111] In one example, TMR element 802c may be replaced with TMR element 802b in bridge 816. In another example, TMR element 802a may be replaced with TMR element 802d in bridge 816. In another example, TMR element 802c may be replaced with TMR element 802b, and TMR element 802a may be replaced with TMR element 802d in bridge 816.

[0112] In the current sensor configuration 800, the common mode stray magnetic field and the gradient stray magnetic field can be reduced along the X-axis. Regardless of the stray magnetic field distribution along the X-axis, the stray magnetic field distribution can be decomposed into a Taylor series consisting of odd terms and even terms (where the TMR elements 802b, 802c are at X = 0). In the following equations, for simplicity, only the common mode and linear components are considered. The signals from the TMR elements 802a, 802b, 802c, and 802d are Sig, respectively. A 、Sig B 、Sig C 、Sig D ,in:

[0113] Sig A =Off+I·Sens I +α·H 0 -α·δx·H 1

[0114] Sig B =Sig C =Off-I·Sens I +α·H 0

[0115] Sig D =Off+I·Sens I +α·H 0 +α·δx·H 1

[0116] And, where:

[0117] Off is the reference offset of the TMR element.

[0118] Sens I is the sensitivity to the current flowing in conductor 806,

[0119] I is the current flowing in conductor 806,

[0120] α is the sensitivity to the magnetic field,

[0121] H 0 and H 1 are the common mode stray field and the linear gradient stray field,

[0122] δx is the distance between TMR element 802a and TMR element 802b, which is equal to the distance between TMR element 802b and TMR element 802d.

[0123] The current difference at the output or node I and node J of bridge 814 is:

[0124] Output = (Sig B+Sig C )–(Sig A +Sig D )

[0125] =(2·Off-2·I·Sens I +2·α·H 0 )–(2 Off+2 I Sens I +2·α·H 0 -α·δx·H 1 +α·δx·H 1 )

[0126] =-4I·Sens I

[0127] Due to the symmetry, the odd terms of the Taylor series are suppressed, not just the linear gradient. In addition, the difference bridge 816 suppresses the even terms of the Taylor series of the stray field distribution (including the common mode). Therefore, depending on the symmetry of the stray field distribution, the proposed structure or a simple difference field can be selected. In the case of a current sensor, the stray magnetic field usually comes from the adjacent current line, so that the distribution of the stray magnetic field is in the form of 1 / (xx 0 ), where x 0 is the distance from the current line. In the current sensor configuration 800, most of the stray magnetic field is kept in common mode and linear gradient, so that the current sensor configuration 800 will reject a larger amount of stray magnetic field.

[0128] Reference Fig. 9 , graph 900 depicts the relationship between unsuppressed stray magnetic field and line distance. Curve 902 depicts a conventional technique for making a current sensor. Curve 906 depicts a current sensor using current sensor configuration 800.

[0129] Reference Fig. 10A , the current sensor configuration 1000 is another example of the current sensor configuration 800, but uses vertical Hall elements. The current sensor includes vertical Hall elements (e.g., vertical Hall element 1002a, vertical Hall element 1002b, vertical Hall element 1002c, and vertical Hall element 1002d) and a double-turn conductor 1006.

[0130] Each of the vertical Hall elements 1002a, 1002b, 1002c, and 1002d includes a reference direction that is the same as the other vertical Hall elements. For example, the vertical Hall element 1002a has a reference direction 1010a, the vertical Hall element 1002b has a reference direction 1010b, the vertical Hall element 1002c has a reference direction 1010c, and the vertical Hall element 1002d has a reference direction 1010d.

[0131] The vertical Hall elements 1002a, 1002b, 1002c, 1002d are located on top of the conductor 1006. The vertical Hall elements 1002a, 1002b, 1002c, 1002d are located on the top of the conductor 1006. Fig. 10A During operation, current 1016 is applied to one end of conductor 1006. In one example, TMR elements 1002a, 1002b, 1002c, 1002d may be spaced apart from conductor 1006 by a distance of 50 microns to 200 microns.

[0132] The vertical Hall element 1002b is placed side by side with the vertical Hall element 1002c. The distance between the TMR element 1002a and the vertical Hall element 1002b is substantially the same as the distance between the vertical Hall element 1002b and the vertical Hall element 1002d.

[0133] refer to Fig. 10B , circuit 1020 processes the signal from the vertical Hall element to reduce stray magnetic fields. Signal S VHA is the output signal of the vertical Hall element 1002a, signal S VHB is the output signal of the vertical Hall element 1002b, signal S VHC is the output signal of the vertical Hall element 1002c, and the signal S VHD is the output signal of the vertical Hall element 1002d. Signal S VHB Equal to signal S VHC .

[0134] The circuit 1020 includes a difference circuit 1026a, a difference circuit 1026b, and a difference circuit 1026c. The difference circuit 1026a obtains the signal S VHA and S VHB The difference between VHA -S VHB The difference circuit 1026b obtains the signal S VHC and S VHD The difference between VHC -S VHD The difference circuit 1026c obtains the signal S VHC -S VHD and S VHA -S VHB The difference between VHC -S VHD )-(S VHA -S D H B )=2S VHC -S VHA -S VHDThe output signal 1050.

[0135] refer to Fig.11A , the current sensor configuration 1100 includes planar Hall elements (eg, planar Hall element 1102 a , planar Hall element 1102 b , planar Hall element 1102 c , and planar Hall element 1102 d ) and three turns of conductor 1106 .

[0136] Planar Hall elements 1102a, 1102b, 1102c, 1102d are located between turns of conductor 1106. Planar Hall elements 1102a, 1102b, 1102c, 1102d are located between turns of conductor 1106. Fig.11A During operation, current 1116 is applied to one end of conductor 1106.

[0137] The planar Hall element 1102b is placed side by side with the planar Hall element 1102c. The distance between the TMR element 1102a and the planar Hall element 1102b is substantially the same as the distance between the planar Hall element 1102b and the planar Hall element 1102d.

[0138] refer to Fig. 11B , circuit 1120 processes the signal from the vertical Hall element to reduce stray magnetic fields. Signal S PHA is the output signal of the vertical Hall element 1102a, signal S PHB is the output signal of the vertical Hall element 1102b, signal S PHC is the output signal of the vertical Hall element 1102c, and the signal S PHD is the output signal of the vertical Hall element 1102d. Signal S PHB Equal to signal S PHC .

[0139] The circuit 1120 includes a difference circuit 1126a, a difference circuit 1126b, and a difference circuit 1126c. The difference circuit 1126a obtains the signal S PHA and S PHB The difference between PHA -S PHB The difference circuit 1126b obtains the signal S PHC and S PHD The difference between PHC -S PHD The difference circuit 1126c obtains the signal S PHC -S PHD and S PHA -S PHB The difference between PHC -S PHD )-(S PHA-S PHB )=2S PHC -S PHA -S PHD The output signal 1150.

[0140] Having described embodiments to illustrate the various concepts, structures, and techniques that are the subject of this patent, it will now be apparent to those skilled in the art that other embodiments incorporating these concepts, structures, or techniques may be used.

[0141] The elements of the different embodiments described herein can be combined to form other embodiments that are not specifically described above. The various elements described in the technical background of a single embodiment can also be arranged separately or in any applicable sub-combination. Other embodiments that are not specifically described herein are also within the scope of the appended claims.

Claims

1. A magnetic field current sensor, comprising: An annihilation detector, the annihilation detector comprising: An annihilation bridge, the annihilation bridge comprising a magnetoresistive element; a current bridge comprising at least two of the magnetoresistive elements; a first comparator configured to compare output signals from the annihilation bridge; and a second comparator configured to compare an output signal from the current bridge, Wherein the output of the annihilation detector indicates whether annihilation is present in one or more of the magnetoresistive elements using at least one of the output signal of the first comparator and the output signal of the second comparator.

2. The magnetic field current sensor according to claim 1, wherein: The annihilation detector further comprises an OR circuit configured to receive an output signal from the first comparator and an output signal from the second comparator, the OR circuit configured to provide an output signal of the annihilation detector, the output signal of the annihilation detector indicating whether the current sensor operates within a linear range.

3. The magnetic field current sensor according to claim 1, wherein: The magnetoresistive element comprises: a first tunnel magnetoresistive (TMR) element; A second TMR element; a third TMR element; and Fourth TMR element.

4. The magnetic field current sensor according to claim 3, wherein: The first TMR element, the second TMR element, the third TMR element, and the fourth TMR element each include a free layer forming a magnetic disk.

5. The magnetic field current sensor according to claim 4, wherein: Each of the first TMR element, the second TMR element, the third TMR element, and the fourth TMR element has a reference direction along a first direction.

6. The magnetic field current sensor according to claim 5, wherein: The first TMR element is part of a first branch of the annihilation bridge, wherein the second TMR element is part of the second branch of the annihilation bridge, wherein the third TMR element is part of the first branch of the annihilation bridge, and The fourth TMR element is a part of the second branch of the annihilation bridge.

7. The magnetic field current sensor according to claim 6, wherein: The first TMR element and the second TMR element are located on top of a single turn conductor.

8. The magnetic field current sensor according to claim 7, wherein: The third TMR element and the fourth TMR element do not contact the single-turn conductor located between the first TMR element and the second TMR element.

9. The magnetic field current sensor according to claim 8, wherein: The distance from the first TMR element to the second TMR element is equal to the distance from the third TMR element to the fourth TMR element.

10. The magnetic field current sensor according to claim 8, wherein: The second TMR elements are interleaved with the third TMR elements.

11. The magnetic field current sensor according to claim 10, wherein: The first TMR element, the second TMR element, the third TMR element and the fourth TMR element are located at least on the same plane.

12. The magnetic field current sensor according to claim 5, wherein: The first TMR element is part of a first branch of the current bridge, wherein the second TMR element is part of the first branch of the current bridge, wherein the first TMR element is part of the second branch of the current bridge, and The second TMR element is part of the second branch of the current bridge.

13. The magnetic field current sensor according to claim 5, wherein: The first TMR element, the second TMR element, the third TMR element, and the fourth TMR element are located on top of a double-turn conductor.

14. The magnetic field current sensor according to claim 13, wherein: The distance from the first TMR element to the second TMR element is equal to the distance from the third TMR element to the fourth TMR element.

15. The magnetic field current sensor according to claim 13, wherein: The second TMR and the third TMR elements are interleaved.

16. The magnetic field current sensor according to claim 15, wherein: The first TMR element, the second TMR element, the third TMR element and the fourth TMR element are on the same plane.

17. The magnetic field current sensor according to claim 16, wherein: The first TMR element is part of a first branch of the annihilation bridge, wherein the second TMR element is a part of the first branch of the annihilation bridge, wherein the third TMR element is part of the second branch of the annihilation bridge, and The fourth TMR element is a part of the second branch of the annihilation bridge.

18. The magnetic field current sensor according to claim 5, wherein: The first TMR element is formed in a first column having a first diameter, wherein the second TMR element is formed in a second column having the first diameter, wherein the third TMR element is formed in a third column having a second diameter different from the first diameter, and Wherein, the fourth TMR element is formed in a fourth column having the second diameter.

19. The magnetic field current sensor according to claim 18, wherein: The first diameter is smaller than the second diameter.

20. The magnetic field current sensor according to claim 19, wherein: The first TMR element, the second TMR element, the third TMR element, and the fourth TMR element are located on top of a single turn conductor.

21. The magnetic field current sensor according to claim 20, wherein: The first TMR element and the third TMR element are located on top of one end of the single-turn conductor, Wherein, the second TMR element and the fourth TMR element are located on the top of the other end of the single-turn conductor.

22. The magnetic field current sensor according to claim 21, wherein: The distance between the first TMR element and the third TMR element is about 20 micrometers, and Wherein, the distance between the first TMR element and the second TMR element is about 400 microns.

23. The magnetic field current sensor according to claim 22, wherein: a first bridge including the first TMR element and the second TMR element forming a first branch of the first bridge, the first TMR element being closer to a first current source in electrical series than the second TMR element, The first bridge further comprises the first TMR element and the second TMR element forming a second branch of the first bridge, the second TMR element being closer to the first current source than the first TMR element in terms of electrical series connection, wherein the second bridge comprises the third TMR element and the fourth TMR element forming a first branch of the second bridge, the third TMR element being closer to the second current source than the fourth TMR element in terms of electrical series connection, The second bridge further comprises the third TMR element and the fourth TMR element forming a second branch of the second bridge, the fourth TMR element being closer to the second current source than the third TMR element in terms of electrical series connection, One of the first bridge and the second bridge is the annihilation bridge.

24. The magnetic field current sensor according to claim 23, wherein: The other of the first bridge and the second bridge is the current bridge.

25. The magnetic field current sensor according to claim 4, wherein: The first TMR element, the second TMR element, the third TMR element, and the fourth TMR element are located on top of a single turn conductor.

26. The magnetic field current sensor according to claim 25, wherein: The first TMR element and the fourth TMR element are located on top of one end of the conductor, Wherein, the second TMR element and the third TMR element are located on the top of the other end of the conductor.

27. The magnetic field current sensor according to claim 26, wherein: The first TMR element and the third TMR element are located on a first axis, Wherein, the second TMR element and the fourth TMR element are located on a second axis, Wherein, the first axis is parallel to the second axis.

28. The magnetic field current sensor according to claim 27, wherein: The first bridge comprises a first branch and a second branch, wherein, on the first branch, the first TMR element is closer to a first current source in electrical series than the second TMR element, the second TMR element is closer to the first current source in electrical series than the third TMR element, and the third TMR element is closer to the first current source in electrical series than the fourth TMR element, wherein, on the second branch, the third TMR element is closer to the first current source in electrical series than the fourth TMR element, the fourth TMR element is closer to the first current source in electrical series than the first TMR element, and the first TMR element is closer to the first current source in electrical series than the second TMR element, The first bridge is one of the annihilation bridge and the current bridge.

29. A magnetic field current sensor, comprising: conductor; The magnetic field sensing elements include: a first magnetic field sensing element, the first magnetic field sensing element generating a first signal; a second magnetic field sensing element, the second magnetic field sensing element generating a second signal; a third magnetic field sensing element that generates a third signal; and a fourth magnetic field sensing element that generates a fourth signal; and a circuit that generates a signal indicative of twice the second signal minus the first signal minus the fourth signal, wherein the second magnetic field sensing element is interlaced with the third magnetic field sensing element, wherein the second signal and the third signal are substantially equal, wherein the first magnetic field sensing element, the second magnetic field sensing element, the third magnetic field sensing element and the fourth magnetic field sensing element are located in a first plane, and The distance between the first magnetic field sensing element and the second magnetic field sensing element is equal to the distance between the second magnetic field sensing element and the fourth magnetic field sensing element.

30. The magnetic field current sensor according to claim 29, wherein: The magnetic field sensing element is a vertical Hall element, Wherein, the vertical Hall element has a reference direction along a first direction, wherein the conductor is a double-turn conductor, and Wherein, the vertical Hall element is in contact with the conductor.

31. The magnetic field current sensor according to claim 29, wherein: The magnetic field sensing element is a planar Hall element, wherein the conductor is a three-turn conductor, and Wherein, the planar Hall element is not in contact with the conductor.

32. A magnetic field current sensor, comprising: an annihilation detector, the annihilation detector comprising a magnetoresistive element, Wherein the output of the annihilation detector indicates whether annihilation is present in one or more of the magnetoresistive elements.

33. The magnetic field sensor of claim 32, wherein: The annihilation detector comprises: an annihilation bridge, the annihilation bridge comprising the magnetoresistive element; and A current bridge includes at least two of the magnetoresistive elements.

34. An annihilation detector comprising: Magnetoresistive element, Wherein the output of the annihilation detector indicates whether annihilation is present in one or more of the magnetoresistive elements.

35. An annihilation detector as claimed in claim 34, wherein The annihilation detector comprises: an annihilation bridge, the annihilation bridge comprising the magnetoresistive element; and A current bridge includes at least two of the magnetoresistive elements.

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