Magnetic multi-turn sensor

Abstract

The invention relates to a magnetic multi-turn sensor. A reluctance track for use in a magnetic multi-turn sensor is provided, the reluctance track comprising one or more annular sections. The annular section includes an intersection at which the reluctance track intersects itself at substantially 90 degrees. In some cases, the annular portion may further be provided with a siphon structure to prevent domain walls that propagate around the reluctance track from becoming stuck at the intersection or propagating in an erroneous direction at the intersection as the external magnetic field rotates.

Description

Technical Field

[0001] The present disclosure relates to a magnetic multi-turn sensor. In particular, the present disclosure relates to a separator structure including one or more annular sections for use in a magnetic multi-turn sensor. Background Art

[0002] Magnetic multi-turn sensors are often used in applications where they monitor the number of times a device is turned around. An example is a steering wheel in a vehicle. Magnetic multi-turn sensors typically include a magnetoresistive element that is sensitive to an applied external magnetic field. The resistance of the magnetoresistive element can be changed by rotating the magnetic field near the sensor. The change in the resistance of the magnetoresistive element can be tracked to determine the number of turns in the magnetic field, which can be converted to the number of turns in the device being monitored.

[0003] Magnetic multi-turn sensors typically contain multiple magnetoresistive elements placed as strips in a spiral or closed loop configuration.

[0004] Other magnetic multi-turn sensors utilize a separator type structure. Summary of the invention

[0005] The present disclosure provides a magnetoresistive track for use in a magnetic multi-turn sensor, the magnetoresistive track comprising one or more annular sections. The annular section comprises a crossover at which the magnetoresistive track crosses itself at substantially 90 degrees. In some cases, the annular section may be further provided with a siphon structure to prevent a domain wall propagating around the magnetoresistive track from becoming stuck at the crossover or propagating in the wrong direction at the crossover when an external magnetic field rotates. By configuring the magnetoresistive track in this manner, the manufacturing complexity of the magnetoresistive track may also be reduced.

[0006] According to aspects of the present disclosure, a magnetic multi-turn sensor is provided, comprising: at least one magnetoresistive track extending in a closed-loop configuration and comprising one or more annular segments, wherein each of the annular segments encloses a corresponding area; and wherein each of the annular segments comprises a first segment of the magnetoresistive track and a second segment of the magnetoresistive track, wherein the first segment of the magnetoresistive track and the second segment of the magnetoresistive track are configured to overlap at an intersection, and a curved segment of the magnetoresistive track extends between the first segment of the magnetoresistive track and the second segment of the magnetoresistive track.

[0007] As such, the reluctance track is provided with a plurality of loops in which portions of the reluctance overlap to thereby provide a cross junction, rather than a Y- or U-shaped junction. By providing a separator type structure having a plurality of loop segments, the problems associated with domain wall nucleation in the crossed regions are reduced compared to domain wall nucleation occurring at a U- or Y-shaped junction. Furthermore, the manufacturing complexity of the reluctance track is also reduced compared to conventional U- or Y-shaped junctions.

[0008] In an example, the reluctance track encloses a region, and each of the annular segments extends from a perimeter of the enclosed region into a corresponding portion of the enclosed region. For example, each of the annular segments may enclose a region within the region enclosed by the reluctance track. The reluctance track may include a first annular segment enclosing a first region and a second annular segment enclosing a second region. The first region and the second region may be different from each other.

[0009] In an example, each of the annular segments includes a separator structure for separating segments of the reluctance track.

[0010] In an example, the reluctance track includes two or more annular sections. Each of the annular sections encloses a corresponding area. That is, each of the annular sections may enclose a separate portion of the inner area enclosed by the reluctance track. In an example, the corresponding areas enclosed by the corresponding annular sections may not overlap.

[0011] In an example, the reluctance track may rotate approximately 360 degrees in each of the annular segments such that a first segment of the reluctance track is substantially perpendicular to the second segment of the reluctance track.

[0012] In an example, the second section of the reluctance track may intersect the first section of the reluctance track at a 90 degree angle. That is, the first section and the second section of the reluctance track may intersect to form a substantially X-shaped junction.

[0013] In an example, the reluctance track may rotate 270 degrees between the first section and the second section.

[0014] In an example, each of the annular segments may further include one or more wick segments configured to restrict movement of a magnetic domain wall through the crossover.

[0015] By providing the siphon section, the magnetic domain wall propagating around the reluctance track will propagate straight through the intersection and be prevented from turning or becoming stuck at the intersection. In this way, the domain wall is prevented from traveling in the wrong direction or nucleating at the intersection, which would otherwise cause errors in the sensor output and incorrect turn counts.

[0016] In an example, the siphon section may be arranged proximate to the first section and / or the second section of the reluctance track.

[0017] In an example, the one or more siphon sections may include an S-shaped bend in the reluctance track.

[0018] In an example, the reluctance track may be arranged in a first plane.

[0019] By providing the wicking section to control the movement of the domain wall, the reluctance track can be arranged entirely in a single plane, thus further reducing manufacturing complexity.

[0020] In another example, the first section of the reluctance track may be arranged in a first plane, and the second section of the reluctance track may be arranged in a second plane different from the first plane.

[0021] By providing the reluctance track in two planes at the intersection, the domain wall is prevented from rotating or becoming stuck at the intersection, and will instead run straight across the intersection as required. In this way, the domain wall is prevented from running in the wrong direction or nucleating at the intersection, which would otherwise cause errors in the sensor output and incorrect turn counts.

[0022] In one example, the magnetic turns sensor may further include a spacer layer disposed between the first section and the second section of the magnetoresistive track. For example, the spacer layer may be disposed in the region of the intersection. In this case, the spacer layer may be any suitable non-magnetic material. When doing so, the first section and the second section of the magnetoresistive track in the region of the intersection are disposed on different planes.

[0023] As another example, the substrate on which the magnetic resistance track is disposed may form a bridge and groove configuration in the area of ​​the intersection, wherein one segment of the magnetic resistance track is disposed in the groove and another segment of the magnetic resistance track is disposed on a bridge extending above the groove, so that the two segments of the magnetic resistance cross each other in two different planes.

[0024] In an example, the magnetic turn sensor may further include a plurality of annular segments arranged inline or staggered along the magnetic resistance track.

[0025] It should be understood that the magnetic resistance track can be configured in a variety of ways and can be designed for different device space requirements. In addition, when configured in-line, the siphon section can be omitted between two consecutive annular sections.

[0026] In an example, the magnetic turns sensor may further include a plurality of magnetoresistive tracks, each magnetoresistive track including a different number of annular portions.

[0027] In doing so, the number of rotations of the external magnetic field that can be counted by the magnetic multi-turn sensor may be increased.

[0028] In an example, the plurality of reluctance tracks may include at least a first reluctance track and a second reluctance track, wherein the second reluctance track is disposed within the closed loop of the first reluctance track.

[0029] By providing a second reluctance track arranged within the closed loop of the first reluctance track, the number of turns that can be counted is increased without significantly increasing the size of the sensor. However, it will be appreciated that the reluctance tracks may be arranged in any suitable manner, such as side by side.

[0030] In an example, the at least one reluctance track may include a relatively prime number of annular segments.

[0031] In this way, the number of rotations of the external magnetic field that can be counted by the magnetic multi-turn sensor increases to the product of the mutually prime number of annular segments. For example, the multi-turn sensor may include a magnetoresistive track having a certain number of annular sections as set forth in the following example. However, it should be understood that a different number of annular sections may be provided and that the multi-turn sensors described herein are not limited to the following examples.

[0032] In an example, the magnetic multi-turn sensor may include a plurality of magnetoresistive tracks having 1, 2, 4, 6 annular sections respectively, the annular sections providing a turn counting range of 2*3*5*7=210 turns.

[0033] In an example, the magnetic multi-turn sensor may include a plurality of magnetoresistive tracks having 1, 4, 6, 10 annular sections respectively, the annular sections providing a turn counting range of 2*5*7*11=770 turns.

[0034] In an example, the magnetic multi-turn sensor may include a plurality of magnetoresistive tracks having 2, 4, 6, 10 annular sections respectively providing a turn counting range of 3*5*7*11=1155 turns.

[0035] In an example, the magnetic multi-turn sensor may comprise a plurality of magnetoresistive tracks having 4, 6, 10, 12 annular sections respectively providing a turn counting range of 5*7*11*13=5005 turns.

[0036] In an example, the magnetic turns sensor may further include a plurality of electrical contacts arranged on the reluctance track to thereby define a plurality of sensing elements.

[0037] In an example, the magnetic turns sensor may further include a plurality of straight sections separated by curved portions on the reluctance track; and wherein the plurality of electrical contacts are disposed on at least one of the straight sections of the reluctance track.

[0038] In an example, the sensing element may be arranged at an angle between 0 and 90 degrees relative to a reference direction of the magnetoresistive track.

[0039] In this aspect, the magnetoresistive track is provided with a reference layer having a magnetization pinned in a reference direction.Thus, the sensing element is configured such that it extends in a direction at an angle between about 0 degrees and about 90 degrees relative to the reference direction.

[0040] In an example, the one or more sensing elements may be configured at a 45 degree angle relative to the reference direction.

[0041] In an example, the magnetic turns sensor may further include a plurality of sensing elements arranged at a period of approximately 90 degrees on at least a portion of a corresponding plurality of straight sections of the reluctance track.

[0042] In an example, the one or more sensing elements may be arranged parallel to a reference direction of the magnetoresistive track; and wherein the magnetoresistive track is longer in a direction parallel to the reference direction than in a direction perpendicular to the reference direction.

[0043] In an example, the magnetic turns sensor may further include at least one pair of sensing elements separated by an S-shaped section of the reluctance track and configured to determine a direction of rotation of an external magnetic field.

[0044] By separating the pair of sensing elements by the S-shaped section of the magnetoresistive track, the direction of rotation of the external magnetic field can be determined. The S-shaped section of the magnetoresistive track is configured to slow down the propagation of magnetic domain walls, enabling the resistance changes of each of the sensing elements to be detected at different times, thus enabling the direction of rotation to be determined.

[0045] In an example, the magnetic turns sensor may further include an initialization coil configured to apply a reset magnetic field to the reluctance track, thereby initializing the reluctance track to a known magnetization state.

[0046] In an example, the magnetic turns sensor may be one of a transimpedance sensor or a giant magnetoresistive sensor.

[0047] In an example, the magnetic multi-turn sensor may further include a substrate on which the magnetoresistive track is disposed. In an example, the one or more magnetoresistive tracks may be disposed on a substrate, such as a printed circuit board (PCB) including processing circuitry for processing sensor signals. It should also be understood that the magnetoresistive track may be a giant magnetoresistive (GMR) or tunnel magnetoresistive (TMR) film.

[0048] According to another aspect of the present disclosure, a magnetic multi-turn sensor is provided, which includes at least two magnetoresistive tracks, each of the magnetoresistive tracks extending in a closed-loop configuration and including one or more annular segments, wherein each of the annular segments includes a first segment of the magnetoresistive track and a second segment of the magnetoresistive track, wherein the first segment of the magnetoresistive track and the second segment of the magnetoresistive track are configured to overlap at an intersection, and a curved segment of the magnetoresistive track extends between the first segment of the magnetoresistive track and the second segment of the magnetoresistive track; and wherein each of the magnetoresistive tracks includes a different number of annular segments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present disclosure will now be described, by way of example only, with reference to the accompanying drawings.

[0050] Figure 1 A separator type magnetic structure and its operation according to the prior art are illustrated;

[0051] Figure 2 Further illustrating a magnetic multi-turn sensor including a plurality of separator structures according to the prior art;

[0052] Figure 3 A portion of a separator structure according to the prior art is shown;

[0053] Figure 4 depicts a magnetoresistive track of a magnetic multi-turn sensor according to the present disclosure;

[0054] Figure 5 Further illustrating a magnetoresistive track of a magnetic multi-turn sensor according to the present disclosure;

[0055] FIG. 6A to FIG. 6L depicts the movement of a magnetic domain wall around a magnetoresistive track of a magnetic multi-turn sensor according to the present disclosure;

[0056] Figure 7 depicts a magnetoresistive track of a magnetic multi-turn sensor according to the present disclosure;

[0057] Figure 8 A circular portion of a magnetic resistance track having a siphon structure according to the present disclosure is shown;

[0058] Fig. 9 depicts a magnetoresistive track of a magnetic multi-turn sensor according to the present disclosure;

[0059] Fig.10 depicts a magnetoresistive track of a magnetic multi-turn sensor according to the present disclosure;

[0060] Fig.11 A magnetic multi-turn sensor according to the present disclosure is illustrated;

[0061] Fig.12depicts a magnetoresistive track of a magnetic multi-turn sensor having multiple readout resistors according to the present disclosure;

[0062] Fig.13 depicts a magnetoresistive track of a magnetic multi-turn sensor having multiple readout resistors according to the present disclosure;

[0063] Fig.14 depicts a magnetoresistive track of a magnetic multi-turn sensor having multiple readout resistors according to the present disclosure;

[0064] Fig.15 depicts the crossing of annular portions of a reluctance track according to the present disclosure;

[0065] Fig.16 An example of a magnetic sensor system according to the present disclosure is depicted. DETAILED DESCRIPTION

[0066] Magnetic multi-turn sensors can be used to monitor the turn count of a rotating shaft. To do this, a magnet is usually mounted to the end of the rotating shaft, and the multi-turn sensor is sensitive to the rotation of the magnetic field as the magnet rotates with the shaft. This type of magnetic sensing can be applied to a variety of different applications, such as automotive applications, medical applications, industrial control applications, consumer applications, and many other applications that require information about the position of a rotating part.

[0067] Magnetic multi-turn sensors typically include giant magnetoresistive (GMR) elements or transmissive magnetoresistive (TMR) elements that are sensitive to an applied external magnetic field configured in a spiral or closed loop configuration.

[0068] Another type of magnetic multi-turn sensor 1 utilizes Figure 1 Here, the magnetic resistance track 10 is placed in at least one closed loop, wherein there are multiple separator rings along at least one side of the closed loop. Figure 1 As shown, when the external magnetic field (indicated by the large arrow) rotates, the domain wall propagates around the magnetoresistive track 10, so that the magnetization state of each segment of the track 10 (indicated by the small arrow) changes as the magnetic field rotates. It should be understood that the rotation of the external magnetic field refers to the relative rotation of the magnetic multi-turn sensor 1 and the external magnetic field. That is, the magnetic multi-turn sensor 1 can also rotate in the presence of a fixed external magnetic field.

[0069] In these separator type structures for magnetic multi-turn sensors, the separator ring includes a plurality of 'dead ends' 12. In this regard, as shown in FIG. Figure 3 As further shown, the two curved reluctance tracks push the fixed ends 12 to meet each other to form a Y-shaped junction 30 .

[0070] As the domain wall propagates around the separator-type sensor 1, it is split into two domain walls (e.g., when it is somewhere along the loop). After one rotation, one of the domain walls will propagate around the fixed end 12 and disappear at the tip, while the other will stop around the Y-junction 30 and then release after an additional rotation. Therefore, the number of fixed ends 12 and Y-junctions 30 in the separator-type structure determines the number of turns the magnetic field needs to rotate to return to the original state.

[0071] Therefore, these structures can be used to measure the count of the rotating field. The count limit of a single loop 10 is given by the number N of fixed ends 12 added to the loop 10. Therefore, it takes N+1 turns to return to the original magnetic state. Figure 2 The multi-turn sensor 20 shown illustrates that by combining multiple of these separator structures 21-25 with a prime number of count ranges (i.e., as defined by the number of fixed ends), the overall count range can be enhanced. In this regard, the resulting count range is the multiplication of the individual count ranges of each structure 21-25.

[0072] However, one of the main problems with this separator structure is the area where the two arms of each separator ring are connected, i.e. Figure 3 . The width of the Y-junction track t4 may be twice as wide as the tracks in the other regions t1 to t3 of the sensor, or at least substantially wider. In addition, the magnetoresistive material is typically rounded at the Y-junction 30. Therefore, the Y-junction causes a lack of width uniformity in the magnetoresistive track.

[0073] As a result, the shape anisotropy is significantly reduced in this Y-junction region, making domain wall nucleation at lower magnetic fields inevitable in these regions compared to other areas of the sensor, which limits the useful magnetic operating window. That is, at lower magnetic fields, domain walls will more easily nucleate in these Y-junctions, causing the sensor to operate incorrectly.

[0074] A magnetic multi-turn sensor may include a U-shaped structure and a Y-shaped junction or replace a Y-shaped junction. However, each of the U-shaped structures requires a full 360 degree rotation of the magnetic field to propagate a domain wall through the structure. It may be difficult to manufacture a U-shaped structure or a Y-junction with the correct shape and with an acceptable magnetic window for domain wall propagation.

[0075] The present disclosure aims to overcome these problems by providing a magnetic multi-turn sensor with a separator type structure, wherein a plurality of annular sections are provided along the magnetoresistive track, and the annular section provides a separator structure. The annular section can replace the U-shaped structure of the magnetic multi-turn sensor. Each of the annular sections includes a cross-shaped junction, and the magnetoresistive track crosses itself at substantially 90 degrees at the cross-shaped junction. Compared with the Y-junction, the cross-shaped junction or intersection has significantly lower manufacturing complexity, and thus the manufacture of the magnetic multi-turn sensor can be simplified. In some examples, instead of a flat or substantially flat cross-shaped junction, the magnetoresistive track can cross itself at substantially 90 degrees via an upper / lower path, wherein the magnetoresistive track is arranged in two separate planes at the intersection. That is, the magnetoresistive track can be arranged to rotate to approach the previous section of the magnetoresistive track, and the plane can be changed before crossing itself, so that the first section of the magnetoresistive track extends along the first direction in the first plane, and the second section of the magnetoresistive track crosses the first section in a second direction substantially perpendicular to the first direction, wherein the second section of the magnetoresistive track is arranged in a second plane different from the first plane. For example, a spacer layer may be provided between a first segment and a second segment of a reluctance track in a crossed region. As another example, a substrate on which the reluctance track is disposed may be formed with a bridge and groove configuration in a crossed region, wherein one segment of the reluctance track is disposed within the groove and another segment of the reluctance track is disposed on a bridge extending over the groove such that the two segments of the reluctance cross each other in two different planes. In doing so, due to the separation of the first segment and the second segment of the reluctance track, the domain wall pairs may be prevented from rotating and the crossover or crossing may be promoted.

[0076] Figure 4 A magnetoresistive track 4 for a magnetic multi-turn sensor according to the present disclosure is shown. The magnetoresistive track 4 extends in a closed loop configuration and comprises at least one straight section 40,41 and at least one annular section 42,46. Figure 4 The reluctance track 4 shown in FIG. 4 comprises two annular segments 42 , 46 , but it will be appreciated that any number of annular segments may be provided.

[0077] Each of the annular sections 42, 46 of the magnetoresistive track 4 includes a first section 42A of the magnetoresistive track 4, a second section 42B of the magnetoresistive track 4, a curved section 42C of the magnetoresistive track 4, and an intersection 44 or a junction where the first section 42A overlaps with the second section 42B, the first section 42A and the second section 42B being substantially straight sections of the magnetoresistive track 4. The first section 42A of the magnetoresistive track 4 may be understood as an entrance section of the magnetoresistive track 4, which defines the beginning of the annular sections 42, 46. The first section 42A of the magnetoresistive track 4 may extend in a substantially straight line in a first direction. The second section 42B of the magnetoresistive track 4 may be understood as an exit section of the magnetoresistive track 4, which defines the end of the annular sections 42, 46. The second section 42B of the magnetoresistive track 4 may extend in a substantially straight line in a second direction. The second direction may be substantially perpendicular to the first direction, and the second section 42B of the magnetic resistance track 4 may intersect the first section 42A of the magnetic resistance track 4 at the intersection 44. The first section 42A may be connected to the second section 42B by a curved section 42C of the magnetic resistance track 4, so that in the curved section 42C, the magnetic resistance track 4 may be configured to rotate so that the second section 42B extends substantially perpendicularly toward the first section 42A and intersects the first section 42A at the intersection. Therefore, the magnetic resistance track 4 may rotate 270 degrees in the curved section 42C.

[0078] As described above, the intersection 44 may also be referred to as a junction. The intersection 44 may be a cross-shaped intersection, in which the first segment 42A and the second segment 42B of the reluctance track 4 meet each other at a 90-degree angle. That is, the first segment 42A and the second segment 42B of the reluctance track 4 intersect to form a substantially X-shaped junction. As will be described below, the intersection 44 may be configured so that the domain wall can only travel straight across the intersection 44. That is, the intersection 44 may be configured so that the domain wall cannot rotate at the intersection 44, and will travel between the first segment 42A and the second segment 42B via the annular portion 42C. It should be understood that in some examples, the second segment 42B of the reluctance track 4 and the first segment 42A of the reluctance track 4 are perpendicular to each other at the intersection 44. However, in other examples, the first segment 42A and the second segment 42B may intersect each other at different angles, that is, the intersection angle may not be exactly 90 degrees, but may be similar.

[0079] The annular sections 42, 46 of the magnetic resistance track 4 may be configured as follows. The magnetic resistance track 4 may include a connecting section 47 disposed adjacent to the annular section 42. The connecting section 47 may be configured as follows. Figure 4 The straight or substantially straight section of the magnetic resistance track 4 shown, but the present disclosure is not limited thereto. The magnetic resistance track 4 may include a second connecting section 48 separated from the first connecting section 47 by an annular section 42. The first connecting section 47 and the second connecting section 48 extend in the same direction, so that the magnetic resistance track 4 rotates a full 360 degrees in the annular section 42. Figure 4 As shown, the reluctance track 4 may include a corner section 49 in which the reluctance track 4 turns 90 degrees before the first section 42A of the annular section 42. Therefore, the reluctance track 4 may turn 360 degrees between the first connection section 47 and the second connection section 48, and the second connection section 48 may be laterally offset from the first connection section 47. That is, the second connection section 48 may extend substantially parallel to the first connection section 47. By configuring the reluctance track 4 in this manner, the intersection 44 in which the reluctance track 4 crosses itself is configured as a cross in which the reluctance track 4 crosses itself at 90 degrees.

[0080] Each of the annular segments 42, 46 may be configured to enclose a corresponding area. That is, each of the annular segments 42, 46 may enclose an area that is separate and different from the area enclosed by the other annular segment 42, 46. Figure 4 In the example of FIG. 4 , the first annular segment 42 encloses a first area and the second annular segment 46 encloses a second area. Figure 4 In the example of the first enclosed area and the second enclosed area do not overlap. In addition, each of the annular segments 42 and 46 can enclose an area inscribed in the area enclosed by the magnetic resistance track 40. That is, each of the annular segments 42 and 46 can extend from the outer periphery of the area enclosed by the magnetic resistance track 40 to the inner area of ​​the area enclosed by the magnetic resistance track 40.

[0081] As will be described further below, the magnetoresistive track 4 may be provided with a plurality of electrical contacts for sensor readout such that a plurality of sensing elements are defined between the electrical contacts.

[0082] By configuring the magnetoresistive track 4 in this way, domain wall nucleation can be reduced in the cross-junction 44 compared to previously used Y- or U-junctions. Furthermore, lower manufacturing complexity is achieved compared to prior art magnetic multi-turn sensors because the cross-junction 44 is significantly easier to manufacture using known deposition and etching techniques than previously used Y- or U-junctions.

[0083] The magnetoresistive track 4 may be formed by a magnetoresistive film comprising a layer stack, the film comprising at least a substrate, a reference layer and a free layer. The free layer may be a ferromagnetic layer that freely aligns its magnetization with an external field. It should be understood that the free layer may be formed by multiple ferromagnetic layers, such as a CoFe layer followed by a nickel iron (NiFe) layer. The free layer may be disposed on a pinned reference layer. The pinned reference layer may comprise multiple layers. The pinned reference layer may comprise a ferromagnetic material having a magnetization pinned in a reference direction. Therefore, when the magnetization direction of the free layer changes between parallel and antiparallel relative to the magnetization direction of the pinned layer (e.g., due to a change in the relative orientation of the free layer and the external magnetic field), a change in the film resistance is observed. The magnetoresistive track 4 is formed to allow magnetic domain walls to propagate around the magnetoresistive track 4.

[0084] Figure 5 A method for initializing a magnetic multi-turn sensor for use in a Figure 4 An example initialization procedure for a magnetoresistive track 4 is shown in which a reset field 50 is applied to the magnetoresistive track 4. As discussed above, the magnetoresistive track 4 may be provided with a reference pinned layer having a fixed magnetization direction, and a free layer having a magnetization that is free to change direction when an external magnetic field is applied. The reset field 50 is a strong magnetic field that may be generated by applying an electric current to an external device, such as a coil or wire electrically isolated above or below the magnetoresistive track 4. When the reset field 50 is applied to the magnetoresistive track 4, a plurality of magnetic domain walls 48A, 48B are formed in the corners of the magnetoresistive track 4, thereby magnetizing the free layers of the sensing elements of the magnetoresistive track 4 to a known state, for example, all sensing elements provide a high resistance or low resistance reading, or a half-high and half-low reading, depending on the direction of the applied reset field 50 relative to the magnetization direction of the reference pinned layer. As shown in FIG. Figure 5 As shown by tail-to-tail arrows 48A and head-to-head arrows 48B in FIG. 1 , the magnetic domain walls 48A, 48B may include a pair of magnetic domain walls.

[0085] After applying the reset magnetic field 50, there may be n domain wall pairs in a magnetoresistive track comprising n turns. As explained above, in the presence of an external rotating magnetic field (e.g., generated by a magnet coupled to a rotating mechanical system), the domain wall propagates around the magnetoresistive track 4 due to the change in the magnetization direction of the free layer relative to the pinned reference layer, resulting in a change in the measured resistance of each sensing element. Therefore, in the case of n domain wall pairs, the domain wall state will be reset after a single turn of the external rotating magnetic field, that is, the resistance measured across each sensing element will be repeated after each turn, and therefore the sensor will only be able to count one complete rotation turn. Therefore, it is desirable to remove one or more of the magnetic domain wall pairs. To this end, one or more coils may be used to excite one or more portions of the magnetoresistive track 4 to provide local annihilation of at least one magnetic domain wall pair. In some cases, all domain wall pairs except one domain wall pair may be removed.

[0086] FIG. 6A to FIG. 6L The magnetoresistive track 4 used in the magnetic multi-turn sensor is shown after an initialization procedure has been performed so that there are two domain walls 48A, 48B configured in the magnetoresistive track 4. The initialization procedure may be as described above with respect to Figure 5 As described above, the magnetoresistive track 4 is initialized to a known state by applying a reset field 50 to fill the magnetoresistive track 4 with magnetic domain walls, and then removing one or more of the magnetic domain wall pairs. As described above, in the initialized state, the magnetoresistive track 4 includes a single domain wall pair 48A, 48B (e.g., Fig. 6A), or with n-1 domain wall pairs, where n is the number of turns of the reluctance track 4. In either of these states, the depicted reluctance track 4 will have a different magnetic state, and therefore a different resistance readout with each 90 degree rotation of the external magnetic field 60. As will be explained below, each of these state changes can be detected by one or more resistors disposed along the reluctance track 4.

[0087] FIG. 6A to FIG. 6L The rotation of the external magnetic field 60 and the corresponding movement of the domain wall pairs 48A, 48B around the reluctance track 4 are depicted.

[0088] FIG. 6A to FIG. 6D A first turn of the external magnetic field 60 is shown. Fig. 6A An external magnetic field 60 is shown at an angle of 45 degrees relative to the reluctor track 4 . Figure 6B An external magnetic field 60 is shown at an angle of 135 degrees relative to the reluctance track 4, wherein for example the magnetic field 60 has been Fig. 6A Rotate 90 degrees clockwise. Figure 6C An external magnetic field 60 is shown at an angle of 225 degrees relative to the reluctance track 4, wherein for example the magnetic field 60 has been Figure 6B Rotate 90 degrees clockwise. Fig.6D An external magnetic field 60 is shown, which is at an angle of 315 degrees relative to the reluctance track 4 which is at an angle of 315 degrees to the external magnetic field 60, wherein for example the magnetic field 60 has been Figure 6C Rotate 90 degrees clockwise.

[0089] Fig. 6E An external magnetic field 60 is shown at an angle of 45 degrees relative to the reluctance track 4, wherein for example the magnetic field 60 has been Fig.6D Rotate another 90 degrees clockwise. Fig. 6E Draw on Fig. 6A The positions of the magnetic domain wall pairs 48A, 48B after the magnetic field 60 has completely rotated relative to the external magnetic field 60. FIG. 6F to FIG. 6L Each depicts another 90 degree rotation of the external magnetic field 60 relative to the magnetic multi-turn sensor comprising the magnetoresistive track 4 . Figure 6L The state of the magnetic multi-turn sensor comprising the magnetoresistive track 4 is shown after 3 complete rotations of the external magnetic field 60. The magnetic multi-turn sensor returns to the same position as the magnetic field after 3 complete rotations. Fig. 6A The same status.

[0090] It will be appreciated that the number of rotations that can be counted by the magnetic multi-turn sensor depends on the number of turns of the reluctance track 4 and therefore on the number of annular segments 42, 46 thereof, since this defines the number of different magnetic states of the sensing element as the pairs of domain walls 48A, 48B propagate around the sensor track 4. The present disclosure is not limited to the number of annular segments 42, 46 depicted in the figures and therefore also is not limited to magnetic multi-turn sensors for counting 3 rotations, but may also include magnetic multi-turn sensors for counting different numbers of rotations.

[0091] Figure 7 Another configuration of the reluctance track 7 is shown. Figure 7 The magnetic resistance track 7 also includes a plurality of straight sections 70, 71 and a plurality of annular sections 72, 76, each of which includes a first section 72A of the magnetic resistance track 7, a second section 72B of the magnetic resistance track 7, the second section being configured to cross the first section 72A at 90 degrees at the intersection 74 and connected to the first section 72A through a curved section 72C. Figure 4 6 , and for the sake of brevity, a detailed description of the common features is omitted.

[0092] Figure 7 The magnetic resistance track 7 and Figure 4 The difference of the reluctance track 4 lies in the configuration of the multiple annular segments 72, 76. Figure 7 In the magnetic resistance track 7, the two annular sections 72 and 76 are arranged in series, and Figure 4 The annular segments 42, 46 are staggered. It should be understood that the exact location of the crossover 74 relative to the annular segments 72, 76 is not limited to the location shown in the figure. For example, consider Figure 7 The magnetic resistance track 7 can count the number of rotations of the external magnetic field as described above for Figure 4 The same is described for the magnetic resistance track 4 of FIG. 6. However, if individual annular segments (such as Figure 7 The second annular section 76 of the embodiment is rotated 90 degrees, and the magnetic domain wall passing through will be at the same Figure 4 The 90 degree phase difference in the reluctance track 4 of FIG. 6 enters and leaves the annular section 76 .

[0093] It should be understood that Figure 4 6, the positions of the annular segments 42, 46, 72, 76 may be different from the positions shown in the drawings. For example, although the annular segments 42, 46, 72, 76 are shown along the top edge of the substantially rectangular reluctance tracks 4, 7 in the drawings, the annular segments 42, 46, 72, 76 may be arranged along different edges or multiple edges of the reluctance tracks 4, 7.

[0094] Figure 8An annular segment 80 of a reluctance track with a siphon structure 86 according to the present disclosure is depicted. As has been discussed above, when the external magnetic field rotates relative to the reluctance track, a magnetic domain wall can propagate around the reluctance track. The magnetic domain wall can travel through a crossover 84 where a first segment 81 of the annular segment 80 and a second segment 83 of the annular segment 80 cross each other at substantially 90 degrees. As previously described, the first segment 81 and the second segment 83 of the annular segment 80 are connected via a curved segment 82 of the reluctance track.

[0095] like Figure 8 As shown, one or more wick structures 86 may be disposed on the magnetoresistive track between the curved section 82 and the first section 81 and / or the second section 83. The wick structure 86 includes a portion of the magnetoresistive track having a curve or an S-shape. The wick structure 86 is shaped so as to allow the magnetic domain wall to cross straight across the intersection 84, but prevent the magnetic domain wall from rotating at the intersection 84 or being stuck (i.e., pinned) at the intersection 84. For example, the angle, curvature, and length of the curved portion of the wick structure are designed so that the magnetic field angle under which the domain wall propagates along each sensing element prevents the magnetic domain wall from rotating at the intersection 84. That is, the wick structure 86 is used to cause a delay in the movement of the magnetic domain wall when the external magnetic field rotates, so that when the magnetic domain wall arrives at the intersection 84, the main driving force component of the external magnetic field drives the magnetic domain wall to cross the intersection 84 straightly. By providing the wick structure 86, a magnetoresistive track including the intersection 84 can also be formed in a single plane. It should be understood that this means that the reluctance track can be flat at the intersection 84 and the first section 81 and the second section 83 of the reluctance track are substantially in the same plane, or the second section 83 of the annular section 85 can be placed directly on top of the first section 81 at the intersection 84.

[0096] The siphon structure 80 may be included in any of the previously discussed reluctance tracks. Fig. 9 and Fig.10 A reluctance track 9, 10 is shown comprising a plurality of annular segments 91, 92, 102, 104, each comprising a crossover 98, 108 as described above, and one or more siphon structures 96, 106 indicated by way of example by a dashed box. Fig.10 In the configuration shown, in which the first annular segment 102 and the second annular segment 104 are configured so that there is no change in the orientation of the reluctance track 100 therebetween, the siphon structure between the intersections 108 of the first annular segment 102 and the second annular segment 104 can be omitted. In this case, the magnetic domain wall can propagate through both intersections 108 at the same magnetic field angle, i.e., no magnetic field rotation is required.

[0097] In some examples, the siphon structure 86 may be omitted. In such a case, at least a portion of the annular segments of the reluctance track may be arranged in more than one plane, optionally with a spacer layer disposed between the reluctance track segments in different planes, such that at the intersection, a second portion of the annular segment travels above or below a first portion of the annular segment. For example, Fig.15 A cross-sectional view of a crossover 150 of an annular segment is depicted, wherein a spacer layer 154 is disposed between a first segment 152A and a second segment 152B of a reluctance track. In this case, it should be understood that the spacer layer may be formed of any suitable non-magnetic material, such as aluminum oxide (Al2O3), silicon nitride (Si3N4), silicon oxide (SiO2), tantalum, ruthenium, titanium, or titanium tungsten. In doing so, the spacer layer does not interfere with the propagation of the domain wall. As another example, the substrate on which the reluctance track is formed may be configured with a groove and bridge configuration to allow the first and second portions of the annular segment to pass over each other. Such a configuration may also prevent the magnetic domain wall from being able to rotate at the crossover and ensure that it spans the crossover straight.

[0098] Fig.11 A multi-turn sensor 110 according to the present disclosure is shown. Fig.11 In an example, a first magnetoresistive track 112 and a second magnetoresistive track 114 embedded in a closed loop of the first magnetoresistive track 112 are provided. The first magnetoresistive track 112 and the second magnetoresistive track 114 each include a plurality of annular segments. The first magnetoresistive track 112 includes three annular segments 112A, 112B, 112C. The second magnetoresistive track 114 includes two annular segments. By configuring the second magnetoresistive track 114 within the loop of the first magnetoresistive track 112, the device size requirements can be improved (e.g., compared to expanding the number of annular segments of the first magnetoresistive track 112).

[0099] Despite Fig.11 The first magnetoresistive track 112 is illustrated as having three annular segments 112A, 112B, 112C, and the second magnetoresistive track 114 is illustrated as having two annular segments, but the present disclosure is not limited thereto. The first magnetoresistive track 112 and the second magnetoresistive track 114 may each have any number of annular segments. However, further advantages are achieved when the first magnetoresistive track 112 and the second magnetoresistive track 114 have a mutually prime number of turns. When the first magnetoresistive track 112 and the second magnetoresistive track 114 have a mutually prime number of turns, the number of rotations relative to the external magnetic field that can be counted by a device having the first magnetoresistive track 112 and the second magnetoresistive track 114 is equal to the product of the mutually prime number of turns. Fig.11 In the example of , the magnetic multi-turn sensor 110 is configured to count 2×3=6 rotations. As described above, the first magnetoresistive track 112 and the second magnetoresistive track 114 may have different numbers of turns, or annular segments.

[0100] Furthermore, a magnetic multi-turn sensor may be formed from any number of reluctance tracks as described herein. For example, a magnetic multi-turn sensor may be formed to have a first reluctance track with 13 turns, a second reluctance track inside the first reluctance track with 11 turns, and a third reluctance track inside the second reluctance track with 7 turns. Such a magnetic multi-turn sensor would be able to count 13x11x7=1001 rotations.

[0101] It should be understood that Fig.11 As shown, multiple magnetic resistance tracks 112, 114 are configured to be embedded in each other to achieve an improvement in device size requirements. However, the present disclosure is not limited thereto. In another example, the first magnetic resistance track 112 and the second magnetic resistance track 114 can be configured adjacent to each other on a single substrate surface, or can be disposed on separate substrate surfaces.

[0102] Fig.12 A magnetoresistive track 120 of a magnetic multi-turn sensor according to the present disclosure is shown. Fig.12 The magnetic resistance track 120 and Fig. 9 9, but further includes a plurality of readout points in the form of electrical contacts 126 arranged around the magnetoresistive track 120, whereby sensor readout is performed, the electrical contacts 126 defining a plurality of resistors R1 to R12 (i.e., sensing elements) therebetween. It should be understood that the electrical contacts may be included on any of the magnetoresistive tracks of the other figures described above.

[0103] As described above, in order to determine the rotation of the external magnetic field, a free layer and a pinned reference layer are provided. When the relative orientation of the magnetization direction of the free layer and the magnetization direction of the pinned reference layer (indicated by arrow 121) changes, the resistance change of the resistors R1 to R12 is detected. When the magnetization states of the magnetoresistive track 120 and the pinned reference layer are antiparallel, the resistance may be the highest, and when they are parallel, the resistance may be the lowest. Fig.12 In the example of , the arrow indicates the magnetization direction 121 of the pinned reference layer. Fig.12 , the magnetization direction 121 of the pinned reference layer is at a 45 degree angle to all resistor elements R1 to R12. However, as will be discussed, the present disclosure is not limited thereto. As the external magnetic field rotates, the magnetic domain walls propagate along the magnetoresistive track 120, causing the magnetization of each resistor element R1 to R12 to change as it passes, thereby changing the relative orientation of the magnetization states of the free layer and the pinned reference layer. This will cause a change in resistance that can be detected at the readout point 126 to determine the rotation of the external magnetic field.

[0104] exist Fig.12, a plurality of electrical contacts 126 are arranged on a straight section of the magnetoresistive track 120 at a period of 90 degrees. That is, each time the magnetoresistive track 120 rotates 90 degrees, the magnetoresistive track 120 includes a straight section in which at least one resistor R1 to R12 is provided. In this way, the magnetic multi-turn sensor can detect a state change in response to a 90-degree rotation of the external magnetic field. It should be understood that this is an example, and a different number of resistors R1 to R12 may be provided, or the resistors R1 to R12 may be provided at different periods. Providing different numbers of resistors R1 to R12 or providing resistors R1 to R12 at different periods may change the sensitivity of the magnetic multi-turn sensor to rotation. For example, as Fig.12 As shown, the plurality of resistors R1 to R12 include a first group of resistors (R2, R4, R6, R10, R12) arranged horizontally on the page and a second group of resistors (R1, R3, R5, R7, R9, R11) arranged vertically on the page. If only the first group or the second group of resistors R1 to R12 are provided, the rotation of the magnetic field can be detected, but the sensitivity of the magnetic multi-turn sensor will be for a turn of 180 degrees.

[0105] Fig.13 Draw something like Fig.12 The magnetic resistance track 120 is the magnetic resistance track 130. However, Fig.13 The reluctance track 130 is further configured to detect the rotation direction of the external magnetic field. Fig.13 The magnetic resistance track 130 includes a magnetic resistance track 130 similar to Fig.12 The plurality of resistors R1 to R12 of the resistors of FIG. 1 are different from the plurality of resistors R1 to R12 of the resistors of FIG. 1 , but include additional resistors (indicated by suffixes "a", "b") separated by the siphon structure 137 or the siphon-like structure 135. That is, Fig.13 The magnetoresistive track 130 includes a plurality of resistor pairs R12a-b, R3a-b, R6a-b, each resistor pair R12a-b, R3a-b, R6a-b includes a first resistor R12a, R3a, R6a and a second resistor R12b, R3b, R6b. The first resistor R12a, R3a, R6a and the second resistor R12b, R3b, R6b are respectively arranged on a first straight section and a second straight section of the magnetoresistive track 130. The first resistor R12a, R3a, R6a and the second resistor R12b, R3b, R6b are separated by the siphon structure 137 or the siphon-like structure 135 described above. The siphon-like structure 135 includes a curved or S-shaped section of the magnetoresistive track 130, but is not formed as part of the cross 134 or the annular sections 132, 136.

[0106] When included in a magnetic multi-turn sensor, Fig.13The magnetoresistive track 130 is configured to allow the determination of the direction of rotation. Specifically, by providing a pair of resistors R12a-b, R3a-b, R6a-b including a first resistor R12a, R3a, R6a and a second resistor R12b, R3b, R6b separated by a siphon structure 137 or a siphon-like structure 135, the direction of rotation can be determined by determining which resistor in the resistor pair R12a-b, R3a-b, R6a-b detects a resistance change first. As discussed above, the siphon structure 137 can slow down the propagation of the magnetic domain wall around the magnetoresistive track 130. This facilitates one of the resistors in the resistor pair R12a-b, R3a-b, R6a-b to detect a magnetization state change before the other resistor in the resistor pair R12a-b, R3a-b, R6a-b, even though the two resistors are configured on the same portion of the magnetoresistive track 130. The siphon-like structure 135 may be understood to function in substantially the same manner.

[0107] Fig.14 Draw something similar to Fig.12 The magnetic resistance track 120 is the magnetic resistance track 140. However, in Fig.14 In the magnetoresistive track 140 of FIG. 1 , multiple resistors R2, R4, R6, R8, R10, R12 all have the same orientation. In this case, since the resistors R2, R4, R6, R8, R10, R12 can detect the state change of the magnetoresistive track 140 when the external magnetic field rotates 180 degrees, the magnetoresistive track 140 can have an elongated shape in the magnetization direction of the reference pinned layer. By aligning the resistors R2, R4, R6, R8, R10, R12 in the direction of the reference pinned layer 141, when the free magnetic layer and the reference pinned layer move between parallel and antiparallel magnetization states, the resistors R2, R4, R6, R8, R10, R12 observe a larger resistance change of a factor of sqrt(2). In addition, the elongated shape of the magnetoresistive track 140 can be advantageous for device area considerations. In this example, the vertical sections of the reluctance track 140 (ie, the sections without any resistors) can be made shorter, which reduces the likelihood of defects.

[0108] Thus, the present disclosure provides a magnetoresistive track comprising one or more annular segments. The annular segments include a crossover at which the magnetoresistive track crosses itself at substantially 90 degrees. By configuring the magnetoresistive track in this manner, the manufacturing complexity of the magnetoresistive track can be reduced. The magnetoresistive track can be included as part of a magnetic multi-turn sensor configured to count the rotation of an external magnetic field. The present disclosure provides a configuration for a magnetoresistive track that ensures that magnetic domain walls can only propagate through the crossover as needed by providing a siphon structure or implementing the magnetoresistive track in two or more planes. In addition, the magnetic multi-turn sensor can be designed to count the desired number of rotations by forming a magnetoresistive track with a specific number of annular segments. Multiple magnetoresistive tracks can be embedded in each other to reduce space requirements. The sensor readout configuration can be configured to achieve a desired sensitivity to magnetic field rotation, or to achieve a slender shape, which can be an advantage for device space requirements. In addition, a siphon structure or a siphon-like structure can be provided between pairs of resistors to allow detection of the direction of rotation.

[0109] In all configurations described herein, it is understood that one or more magnetoresistive tracks may be provided on a printed circuit board (PCB) containing processing circuitry for processing sensor signals. It is also understood that the magnetoresistive tracks may be giant magnetoresistive (GMR) or trans-magnetoresistive (TMR) films.

[0110] Fig.16 A schematic block diagram of an example magnetic sensor system 160 is depicted that includes an xMR multi-turn (MT) sensor 1602, which may include any of the magnetoresistive tracks described herein. The magnetic sensor system 160 may also include a magnetic single turn (ST) sensor 1604, which may be a position sensor based on anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), or trans-magnetoresistive (TMR), but it should be understood that the magnetic sensor system 160 may be implemented without the ST sensor 1604 or with a different type of magnetic angle sensor.

[0111] The sensor system 160 further includes a processing circuit 1606 and an integrated circuit 1600 on which the MT sensor 1602, the ST sensor 1604, and the processing circuit 1606 are disposed. The processing circuit 1606 receives a signal S from the MT sensor 1602. MT 1612 and processes the received signal to determine the turn count using the turn count decoder 1608, which will output a turn count representing the number of turns of an external magnetic field (not shown) rotating near the MT sensor 1602. Similarly, the processing circuit 1606 may also receive a signal S from the ST sensor 1604 ST1614 and processes the received signal using the position decoder 1610 to output the angular position of the external magnetic field.

[0112] application

[0113] Any of the principles and advantages discussed herein may be applied to other systems, rather than just to the system described above. Some embodiments may include a subset of the features and / or advantages set forth herein. The elements and operations of the various embodiments described above may be combined to provide further embodiments. The actions of the methods discussed herein may be appropriately performed in any order. In addition, the actions of the methods discussed herein may be appropriately performed in series or in parallel. Although the circuit is depicted in a specific configuration, other equivalent configurations are also feasible.

[0114] Any of the principles and advantages discussed herein may be implemented in conjunction with any other system, device, or method that may benefit from any of the teachings herein. For example, any of the principles and advantages discussed herein may be implemented in conjunction with any device that requires correction of rotational angular position data derived from a rotating magnetic field. Furthermore, the device may include any magnetoresistive or Hall effect device capable of sensing a magnetic field.

[0115] Aspects of the present disclosure may be implemented in various electronic devices or systems. For example, phase correction methods and sensors implemented according to any of the principles and advantages discussed herein may be included in various electronic devices and / or various applications. Examples of electronic devices and applications may include, but are not limited to, servo systems, robots, aircraft, submarines, toothbrushes, biomedical sensing devices, and parts of consumer electronic products, such as semiconductor dies and / or packaging modules, electronic test equipment, etc. In addition, electronic devices may include unfinished products, including products for industrial, automotive, and / or medical applications.

[0116] Unless the context clearly requires otherwise, throughout the specification and claims, the words “comprise, comprising,” “include, including,” and the like should be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense; that is, in the sense of “including, but not limited to.” As generally used herein, the words “coupled” or “connected” refer to two or more elements that may be directly connected or connected through one or more intermediate elements. Thus, although the various schematic diagrams shown in the drawings depict example configurations of elements and components, additional intermediate elements, devices, features, or components may be present in actual embodiments (assuming that the functionality of the depicted circuits is not adversely affected). As used herein, the words “based on” are generally intended to encompass “based solely on” and “based at least partly on.” In addition, when used in this application, the words “herein,” “above,” “below,” and words of similar meaning shall refer to the entire content of this application rather than to any particular portion of this application. Where the context permits, words used in the specific embodiments in the singular or plural may also include the plural or singular, respectively. The word "or" refers to a list of two or more items, and the word is intended to cover all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list. All numerical values ​​or distances provided herein are intended to include similar values ​​within measurement error.

[0117] Although specific embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. In fact, the novel devices, systems, and methods described herein may be embodied in various other forms. In addition, various omissions, substitutions, and changes may be made to the form of the methods and systems described herein without departing from the spirit of the present disclosure.

Claims

1. A magnetic multi-turn sensor, comprising: at least one reluctance track extending in a closed loop configuration and comprising one or more annular segments, wherein each of the annular segments encloses a respective area; and wherein each of the annular sections includes a first section of a magnetoresistive track and a second section of a magnetoresistive track, wherein the first section of the magnetoresistive track and the second section of the magnetoresistive track are configured to overlap at an intersection, and a curved section of the magnetoresistive track extends between the first section of the magnetoresistive track and the second section of the magnetoresistive track.

2. The magnetic multi-turn sensor of claim 1, wherein the at least one reluctance track rotates approximately 360 degrees in each of the annular segments such that a first segment of the reluctance track is substantially perpendicular to the second segment of the reluctance track. 3 . The magnetic multi-turn sensor of claim 1 , wherein each of the annular segments further comprises one or more wicking segments configured to restrict movement of a magnetic domain wall through the crossover. 4 . The magnetic multi-turn sensor according to claim 3 , wherein the one or more siphon sections are arranged close to the first section and / or the second section of the reluctance track.

5. The magnetic multi-turn sensor of claim 3, wherein the one or more siphon sections comprise an S-shaped bend in the reluctance track.

6. The magnetic multi-turn sensor of claim 3, wherein the at least one magnetoresistive track is arranged in a first plane. 7 . The magnetic multi-turn sensor of claim 1 , wherein the first section of the magnetoresistive track is arranged in a first plane and the second section of the magnetoresistive track is arranged in a second plane different from the first plane.

8. The magnetic multi-turn sensor of claim 7, further comprising a spacer layer disposed between the first section and the second section of a magnetoresistive track, wherein the spacer layer is disposed at least in a region of the intersection. 9 . The magnetic multi-turn sensor according to claim 1 , comprising a plurality of annular segments arranged in series or staggered along the magnetoresistive track.

10. The magnetic multi-turn sensor of claim 1, further comprising a plurality of magnetoresistive tracks, each magnetoresistive track comprising a different number of annular portions. 11 . The magnetic multi-turn sensor according to claim 10 , wherein the plurality of magnetoresistive tracks at least include a first magnetoresistive track and a second magnetoresistive track, wherein the second magnetoresistive track is arranged within the closed loop of the first magnetoresistive track.

12. The magnetic multi-turn sensor of claim 1, wherein the at least one magnetoresistive track comprises a relatively prime number of annular segments.

13. The magnetic multi-turn sensor of claim 1, further comprising a plurality of electrical contacts arranged on the at least one reluctance track to thereby define a plurality of sensing elements.

14. The magnetic multi-turn sensor of claim 13, wherein the at least one reluctance track comprises a plurality of straight sections separated by bends on the reluctance track; and Wherein the plurality of electrical contacts are disposed on at least one of the straight sections of the reluctance track.

15. The magnetic multi-turn sensor of claim 13, wherein the sensing element is configured at an angle between about 0 degrees and about 90 degrees relative to a reference direction of the magnetoresistive track.

16. The magnetic multi-turn sensor of claim 14, further comprising a plurality of sensing elements arranged at a period of approximately 90 degrees on at least a portion of a corresponding plurality of straight sections of the magnetoresistive track.

17. The magnetic multi-turn sensor of claim 13, wherein one or more of the plurality of sensing elements are arranged parallel to a reference direction of the magnetoresistive track; and Wherein the at least one reluctance track is longer in a direction parallel to the reference direction than in a direction perpendicular to the reference direction.

18. The magnetic multi-turn sensor of claim 13, wherein the plurality of sensing elements comprises at least one pair of sensing elements separated by an S-shaped section of the magnetoresistive track and configured to determine a direction of rotation of an external magnetic field.

19. The magnetic multi-turn sensor of claim 1, further comprising an initialization coil configured to apply a reset magnetic field to the at least one reluctance track, thereby initializing the reluctance track to a known magnetization state.

20. A magnetic multi-turn sensor, comprising: at least two reluctance tracks, each of which extends in a closed loop configuration and comprises one or more annular segments, wherein each of the annular sections includes a first section of a reluctance track and a second section of a reluctance track, wherein the first section of the reluctance track and the second section of the reluctance track are configured to overlap at an intersection, a curved section of the reluctance track extending between the first section of the reluctance track and the second section of the reluctance track; and Wherein each of the reluctance tracks includes a different number of annular segments.

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