Re-magnetization of multi-turn spirals

Abstract

To provide a technique for re-magnetization of a multi-turn spiral.SOLUTION: Aspects of the present disclosure relate to systems and methods for re-magnetization of multi-turn loops. In one aspect, a multi-turn magnetic sensing system includes a multi-turn loop through which domain walls propagate in response to a rotation of a magnetic field, and a magnetization component configured to provide the domain walls to the multi-turn loop. The system further includes one or more wires configured to annihilate at least two of the domain walls of the multi-turn loop.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The disclosed technology relates to multi-turn magnetic sensors and related systems and methods. [Background technology]

[0002] The magnetic sensing system can include a multi-turn magnetic sensor that counts the cumulative number of rotations of a magnetic field. The multi-turn magnetic sensor can include magnetoresistive elements arranged in series with one another as spiral strips. The resistance of one or more of the magnetoresistive elements can change in response to the rotation of the magnetic field. The state of the multi-turn magnetic sensor can be decoded from an output signal of the multi-turn magnetic sensor. Summary of the Invention

[0003] Each claimed innovation has several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the claims, we will now briefly discuss some prominent features of the present disclosure.

[0004] One aspect of the present disclosure is a multi-turn magnetic sensing system comprising: a multi-turn loop having domain walls propagating therethrough in response to a rotation of a magnetic field; a magnetizing component configured to provide the domain walls to the multi-turn loop; and one or more wires configured to annihilate at least two of the domain walls of the multi-turn loop.

[0005] In some embodiments, the magnetizing component includes a reset coil wire configured to fill the multi-turn loop with a domain wall.

[0006] In some embodiments, the multi-turn magnetic sensing system further comprises a decoder configured to output a turn count based on the output signal from the multi-turn loop, the decoder configured to determine the turn count based on a location of a domain wall gap formed by the annihilation of at least two of the domain walls.

[0007] In some embodiments, the one or more wires include a re-magnetization coil that wraps around a portion of the multi-turn loop.

[0008] In some embodiments, the one or more wires include a remagnetization component positioned on one side of a portion of the multi-turn loop.

[0009] In some embodiments, the multi-turn loop comprises a multi-turn spiral, and the one or more wires comprise a remagnetizing component that covers at least three-quarters of the turns of the multi-turn spiral.

[0010] In some embodiments, the multi-turn magnetic sensing system further comprises a readout circuit configured to measure a direction of the external magnetic field, and a controller configured to apply a current pulse to the one or more wires with the direction of the current pulse based on the measured external magnetic field.

[0011] In some embodiments, the readout circuitry is further configured to measure a magnetization state of the multi-turn loop, and the controller is configured to verify that at least two of the domain walls have disappeared based on the measured magnetization state of the multi-turn loop.

[0012] In some embodiments, the multi-turn loop includes a multi-turn spiral, the magnetization component includes a domain wall generator configured to generate a domain wall at one end of the multi-turn spiral, and a magnetic target configured to generate an external magnetic field, and providing the multi-turn spiral with a domain wall includes rotating the magnetic target relative to the multi-turn spiral such that the domain wall generated by the domain wall generator propagates around the multi-turn spiral.

[0013] In some embodiments, the magnetizing component includes one or more reset coil wires configured to generate a magnetic field having sufficient strength to fill the multi-turn loop with domain walls.

[0014] In some embodiments, the multi-turn loop comprises a multi-turn spiral including a first spiral and a second spiral, the first spiral and the second spiral being coupled together such that a domain wall can propagate between the first spiral and the second spiral.

[0015] In some embodiments, the one or more wires include a remagnetizing component including multiple sections, and the multi-turn magnetic sensing system further comprises a controller configured to sequentially apply current pulses to the sections of the remagnetizing component.

[0016] Another aspect of the present disclosure is a method of initializing a multi-turn magnetic sensing system, the method including providing a multi-turn loop with domain walls and applying a magnetic field to a portion of the multi-turn loop so as to annihilate at least two of the domain walls of the multi-turn loop, wherein after the applying, the multi-turn loop is configured to change state in response to a rotation of the magnetic field.

[0017] In some embodiments, the method further includes determining a turn count based on an output signal from the multi-turn loop.

[0018] In some embodiments, the determining is based on a location of a domain wall gap formed by the annihilation of at least two of the domain walls.

[0019] In some embodiments, the applying is performed using a coil that wraps around a portion of the multi-turn loop.

[0020] In some embodiments, the method further includes measuring a direction of the external magnetic field, and the applying includes applying a current pulse to the remagnetizing component, the direction of the current pulse being based on the measured external magnetic field.

[0021] In some embodiments, the method further includes measuring a magnetization state of the multi-turn loop and verifying that at least two of the domain walls have disappeared based on the measured magnetization state of the multi-turn loop.

[0022] In some embodiments, providing the multi-turn loop with a domain wall is performed using one or more reset coil wires that generate a magnetic field with sufficient strength to fill the multi-turn loop with a domain wall.

[0023] Yet another aspect of the present disclosure is a multi-turn magnetic sensing system comprising: a multi-turn loop having domain walls propagating therethrough in response to a rotation of a magnetic field; means for annihilating at least two of the domain walls of the multi-turn loop; and a decoder configured to output a turn count based on an output signal from the multi-turn loop.

[0024] Embodiments of the present disclosure will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0025] [Figure 1] 1 illustrates a multi-turn spiral according to an aspect of the present disclosure. [Figure 2]FIG. 1 is a schematic block diagram of a multi-turn magnetic sensing system according to one embodiment. [Figure 3] 1 illustrates a stage in the initialization process of a multi-turn spiral, according to an embodiment of the present disclosure. [Figure 4] 1 illustrates an exemplary pair of domain walls in a multi-turn spiral that can be annihilated by aspects of the present disclosure. [Figure 5] 1 illustrates one embodiment of a multi-turn spiral including one or more wires configured to annihilate at least two domain walls of the multi-turn spiral, according to aspects of the present disclosure. [Figure 6] 1 shows a portion of a remagnetization coil with partially transparent layers to show the connections between the layers. [Figure 7] 10 illustrates the direction of current flow through a remagnetization coil when applied with a current pulse, according to aspects of the present disclosure. [Figure 8] 8 illustrates the magnetization of the multi-turn spiral of FIG. 7 after remagnetization, according to an embodiment of the present disclosure. [Figure 9] 1 illustrates an exemplary cross section of a multi-turn spiral according to aspects of the present disclosure. [Figure 10] 1 illustrates another embodiment of a multi-turn spiral including a remagnetizing component that can be used to remagnetize a portion of the multi-turn spiral, according to aspects of the present disclosure. [Figure 11] 1 illustrates an exemplary method for initializing a multi-turn spiral, according to an aspect of the present disclosure. [Figure 12] 10 illustrates another exemplary method for initializing a multi-turn spiral, according to aspects of the present disclosure. [Figure 13] 10 illustrates another embodiment of a multi-turn spiral including a magnetizing component that can be used to fill the multi-turn spiral with domain walls, according to aspects of the present disclosure. [Figure 14] 1 illustrates another embodiment of a multi-turn spiral according to aspects of the present disclosure. [Figure 15A] 1 illustrates one embodiment of a multi-turn counter loop according to aspects of the present disclosure. [Figure 15B] 1 illustrates another embodiment of a multi-turn counter loop according to aspects of the present disclosure. [Figure 15C] 10 illustrates yet another embodiment of a multi-turn counter loop according to aspects of the present disclosure. [Figure 16] 10 illustrates yet another embodiment of a multi-turn spiral according to aspects of the present disclosure. [Figure 17] 1 illustrates another embodiment of a multi-turn spiral according to aspects of the present disclosure. [Figure 18] 10 illustrates another embodiment of a multi-turn spiral including one or more wires configured to annihilate at least two domain walls of the multi-turn spiral, according to aspects of the present disclosure. [Figure 19] 10 illustrates yet another embodiment of a multi-turn spiral including a remagnetizing component that can be used to remagnetize a portion of the multi-turn spiral, according to aspects of the present disclosure. [Figure 20] 10 illustrates yet another embodiment of a multi-turn spiral including a remagnetizing component that can be used to remagnetize a portion of the multi-turn spiral, according to aspects of the present disclosure. [Figure 21] 1 illustrates an exemplary method for initializing a multi-turn magnetic sensing system according to an aspect of the present disclosure. [Figure 22A] FIG. 1 is a schematic diagram of two multi-turn sensors of a multi-turn magnetic sensing system, according to one embodiment. [Figure 22B] 22B is a table summarizing the states and turn counts of the multi-turn magnetic sensing system of FIG. 22A as the magnetic field rotates. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in many different ways, as defined and encompassed, for example, by the claims. In this description, reference is made to the drawings, where like reference numbers may indicate identical or functionally similar elements. It will be understood that the elements shown in the drawings are not necessarily drawn to scale. It will also be understood that certain embodiments may include more elements than are illustrated in the drawings and / or a subset of the illustrated elements. Furthermore, some embodiments may incorporate any suitable combination of features from two or more drawings. Headings are provided merely for convenience and do not affect the scope or meaning of the claims.

[0027] Multi-turn magnetic sensor Multi-turn magnetic sensors can continuously detect rotational or linear motion without power and can read absolute position upon power-up. Multi-turn magnetic sensors can provide true power-on functionality without receiving electrical power. Multi-turn magnetic sensors can operate based on the principle of magnetic spiral or track-detection motion in the presence of a moving permanent magnet. The magnetic spiral can include nanowires. The magnetic spiral can include giant magnetoresistance (GMR) material or tunneling magnetoresistance (TMR) material. The resistance of the magnetoresistive element of the magnetic spiral can change in response to a rotating magnetic field as the magnetic spiral fills with magnetic domain walls, also known as magnetic domains. This effect is sometimes called morphological anisotropy. The turn count can be decoded from the resistance of the magnetoresistive element of the multi-turn magnetic sensor. The turn count can be combined with the angle detected by the angle sensor to provide absolute multi-turn position information.

[0028] A technical challenge with multi-turn magnetic sensors is initializing and / or resetting the multi-turn magnetic sensor at a midpoint or another specific position in its measurement range. By setting the multi-turn magnetic sensor at such a position, it can accommodate turn counts that fall between the ends of the turn count range. This may be desirable, for example, when a magnetic target is configured to rotate in either direction from its initial position. The present disclosure provides a technical solution to this challenge.

[0029] Embodiments of the present disclosure can initialize or otherwise set a multi-turn magnetic sensor to a particular state. The magnetic turn count information stored in the multi-turn magnetic sensor should correspond to the physical turn count of the system including the multi-turn magnetic sensor. It may be desirable to set the turn count state of the multi-turn sensor to a midpoint or another particular point. One particular initialization technique sets the multi-turn magnetic sensor to an end point of a turn count range. For example, a multi-turn magnetic sensor can be initialized to a state in which the multi-turn magnetic sensor is completely filled with domain walls. The present disclosure provides technical solutions for magnetically setting a multi-turn magnetic sensor to different states.

[0030] Aspects of the present disclosure relate to systems and techniques for remagnetizing a portion of a multi-turn loop, such as a multi-turn spiral, which can be used to set the magnetization of a multi-turn sensor to a particular turn count state other than, for example, the minimum value of the turn count range or the maximum value of the turn count range.

[0031] Resetting a multi-turn magnetic sensor A multi-turn magnetic sensor can be reset by applying a magnetic field having a magnitude higher than the upper magnetic operating limit of the multi-turn magnetic sensor. This can result in the magnetic spiral of the multi-turn magnetic sensor being filled with domain walls. In some applications, such a reset can correspond to the multi-turn magnetic sensor being in a maximum turn count state. In some other applications, resetting the magnetic spiral of a multi-turn magnetic sensor can result in the multi-turn magnetic sensor being in a minimum turn count state with the magnetic spiral empty of domain walls.

[0032] The magnetic spiral can take the form of a clockwise (CW) sensor or a counterclockwise (CCW) sensor. A CW multi-turn magnetic sensor can count turns in the presence of a magnetic field rotating in a CW direction. In such a multi-turn magnetic sensor, the turn count can correspond to the magnetic resistance elements of the magnetic spiral being filled with domain walls. The magnetic resistance elements can be legs of the magnetic spiral. A CCW multi-turn magnetic sensor can count turns in the presence of a magnetic field rotating in a CCW direction. The domain walls propagate in the opposite direction in a CW multi-turn magnetic sensor compared to a CCW multi-turn magnetic sensor.

[0033] Exemplary multi-turn spiral Aspects of the present disclosure relate to systems and techniques for remagnetizing a portion of a multi-turn spiral, which can be used to set the magnetization of a multi-turn sensor to a particular turn count state other than, for example, the minimum turn count range and the maximum turn count range.

[0034] As described herein, certain multi-turn sensors do not have the ability to reset the multi-turn sensor at a midpoint between the minimum and maximum values ​​of the turn count range. For various applications, it may be desirable to reset and / or initialize the multi-turn sensor to a particular turn count state between the minimum and maximum values ​​of the turn count range.

[0035] Accordingly, aspects of the present disclosure provide systems and techniques for initialization of multi-turn sensors that enable new implementations of multi-turn technology. To accurately measure turn count, the magnetic turn count information stored in the sensor must match the physical turn count of the system the sensor is measuring. In many applications, the physical system being measured may be configured to rotate in either direction (e.g., CW or CCW). Therefore, it is desirable to set the turn count state of a multi-turn sensor to a midpoint or another specified point and enable measurements in either direction from the set state.

[0036] FIG. 1 illustrates a multi-turn spiral 100 according to an embodiment of the present disclosure. The multi-turn spiral 100 is an example of a multi-turn loop. As shown in FIG. 1, the multi-turn spiral 100 includes a first spiral 102 and a second spiral 104 coupled together such that a domain wall can propagate between the first spiral 102 and the second spiral 104. The first spiral 102 and the second spiral 104 can include multiple spiral arms, each formed from a single winding of the spiral 102, 104. The first spiral 102 and the second spiral 104 can be formed from a nanowire 103. The multi-turn spiral 100 also includes a domain wall generator 106 at an end of the multi-turn spiral 100. Although embodiments of the present disclosure are described in connection with the multi-turn spiral 100 shown in FIG. 1, aspects of the present disclosure are not limited thereto, and the remagnetization systems and techniques may also be applied to various other types of multi-turn sensors, including, for example, the multi-turn magnetic sensing system 10 of FIG. 22A and / or single spiral multi-turn sensors.

[0037] Multi-turn magnetic sensing system with intermediate position reset The intermediate position reset can be implemented in various multi-turn magnetic sensing systems. Such multi-turn magnetic sensing systems can include a processing circuit and a magnetic reset. The processing circuit can include a signal conditioning circuit and a controller. In certain applications, the multi-turn magnetic system can include one or more additional sensors, such as an angle sensor and / or a quadrant detector. An exemplary multi-turn magnetic sensing system with an intermediate position reset is discussed with reference to FIG. 2.

[0038] FIG. 2 is a schematic block diagram of a multi-turn magnetic sensing system 20 according to one embodiment. The multi-turn magnetic sensing system 20 can track and output a turn count representing the number of turns of an operating magnetic field that can be generated by the rotation of a magnetic target 21 or other magnetic field source. As shown, the magnetic target 21 can be a dipole magnet. In certain applications, the magnetic target 21 can be attached to a rotating shaft. The multi-turn magnetic sensing system 20 includes a multi-turn spiral 100, a signal conditioning circuit 25, a controller 26, and a magnetic reset 27. In some embodiments, the multi-turn spiral 100 can be embodied as the multi-turn spiral 100 of FIG. 1 or any other multi-turn spiral described herein. Exemplary magnetic spirals are shown in FIGS. 1 and 22A.

[0039] The multi-turn spiral 100 can be configured to trace any suitable number of turns for a particular application.

[0040] The output signal from the multi-turn spiral 100 is conditioned by a signal conditioning circuit 25. The signal conditioning circuit 25 may include any suitable circuitry for modifying the raw analog output signal from the multi-turn spiral 100 to make the signal suitable for further processing. The signal conditioning circuit 25 may include, for example, one or more amplifiers and / or one or more filters. The signal conditioning circuit 25 may include a readout circuit 28 that reads out values ​​associated with the magnetoresistive elements of the multi-turn spiral 100. In certain applications, the readout circuit 28 may be implemented according to any suitable principles and advantages disclosed in U.S. Pat. No. 10,782,153, the disclosure of which is hereby incorporated by reference in its entirety for all purposes. The signal generated by the readout circuit 28 may indicate the resistance of one or more of the magnetoresistive elements of the first multi-turn magnetic sensor 22 or the second multi-turn magnetic sensor 24.

[0041] The controller 26 can include a decoder 29 that can determine the cumulative turn count of the operating magnetic field from the output signal from the signal conditioning circuit 25. The controller 26 can digitize the output signal from the signal conditioning circuit 25 using an analog-to-digital converter (ADC). The digital output signal from the ADC can be provided to the decoder 29 for determining the turn count. The controller 26 can output the turn count to a user interface, for example. The user interface can be connected to an inter-integration circuit (IIC). 2 The magnetic reset 27 may be any suitable interface, including, but not limited to, a Serial Peripheral Interface (C) interface or a Serial Peripheral Interface (SPI). The controller 26 may generate a control signal to control the magnetic reset 27. Depending on the embodiment, the controller 26 may include a state machine, a microcontroller, or any other similar controller.

[0042] The decoder 29 may output a turn count representing the cumulative number of turns of the operating magnetic field. The decoder 29 may determine any suitable value, for example, from Table 1B. For example, the decoder 29 may determine the state and turn count of the multi-turn spiral 100. The decoder 29 may determine the state of the multi-turn spiral 100 based on an output signal from the readout circuit 28. The state of the multi-turn spiral 100 may be determined based on a signal representing the resistance of a magnetoresistive element of the multi-turn spiral 100. The decoder 29 may receive a digital input signal and provide the turn count as a digital output signal. In certain applications, the decoder 29 may implement successive approximation decoding to determine the state of the multi-turn spiral 100. Such decoding may be implemented according to any suitable principles and advantages disclosed in U.S. Pat. No. 10,830,613, the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

[0043] The decoder 29 can determine the turn count from the state of the multi-turn spiral 100. An exemplary mapping of turn count to sensor state is provided in FIG. 22B. In decoding the output signal from the readout circuit 28, the decoder 29 can decode a valid pre-balance state and a valid balanced state. The decoder 29 can be a full-turn decoder, a half-turn decoder, or a quarter-turn decoder.

[0044] The controller 26 can control the magnetic reset 27 to reset the multi-turn magnetic sensors 22, 24 to a reset state. Such a magnetic reset can be performed upon system initialization. In such an example, the reset state can be an initial state. In some applications, the magnetic reset can be performed in response to one or more of the following: detecting a system fault; for rollover counting, discussed in more detail below; periodically; after reaching a threshold amount of time for system operation; or in response to detecting any other suitable condition.

[0045] The magnetic reset 27 can include any suitable structure for resetting the multi-turn spiral 100. In certain applications, the magnetic reset 27 can include a wire or coil capable of generating a reset magnetic field greater than the upper operating limit of the multi-turn spiral 100. The controller 26 can apply a current to the wire or coil to generate the reset magnetic field. The wire or coil can fill the multi-turn spiral 100 with domain walls, placing the multi-turn spiral 100 in a reset state. The wire or coil can be mounted on a printed circuit board. In some other applications, the magnetic reset 27 can include a permanent magnet physically proximate to the multi-turn spiral 100 to apply a magnetic field greater than the upper operating limit of the multi-turn spiral 100. For such a permanent magnet, the controller 26 can provide a control signal to bring the permanent magnet close enough to the multi-turn spiral 100 to place the multi-turn spiral 100 in a reset state. The controller 26 can then move the permanent magnet away from the multi-turn spiral 100 to allow the multi-turn magnetic sensing system 20 to track the rotation of the magnetic field.

[0046] Remagnetization of a portion of a multi-turn spiral FIG. 3 illustrates a stage in an initialization process for a multi-turn spiral 2300 according to aspects of the present disclosure. Referring to FIG. 3 , a multi-turn sensor system can apply a magnetic field 110 to fill the multi-turn spiral 100 with domain walls 112. In some embodiments, the magnetic field 110 can be applied by a magnetization component (e.g., magnetic reset 27 of FIG. 2 ). In some embodiments, the magnetization component can include a domain wall generator (e.g., domain wall generator 106 of FIG. 1 ) configured to provide domain walls to the multi-turn spiral 100, which can partially or completely fill the multi-turn spiral 100 as the multi-turn spiral 100 rotates relative to the magnetic target 21. The domain walls 112 can include a tail-to-tail domain wall 112 a and a head-to-head domain wall 112 b. The remaining arrows pointing in one direction indicate the direction of magnetization of the multi-turn spiral 100 between the domain walls 112. After being reset with a magnetic field 110, the multi-turn spiral 100 is filled with domain walls 112, as shown in FIG.

[0047] To initialize the multi-turn spiral 100 to a turn count between a minimum and maximum turn count, the multi-turn sensor can annihilate at least one pair of domain walls 112 of the multi-turn spiral 100. FIG. 4 illustrates an example pair of domain walls 112a, 112b in the multi-turn spiral 100 that can be annihilated according to aspects of the present disclosure. As shown in FIG. 4, the multi-turn sensor system can magnetize a portion 114 of the multi-turn spiral 100 to annihilate the pair of domain walls 112. In some embodiments, a magnetic field can be applied in a direction opposite to the magnetization of the multi-turn spiral 100 to cause the pair of domain walls to propagate in opposite directions and annihilate each other. The pair of domain walls can include a tail-to-tail domain wall 112a and a head-to-head domain wall 112b. In the embodiment of FIG. 4, portion 114 extends from the upper left corner of multi-turn spiral 100 (the upper left corner of first spiral 102) to the lower right corner of multi-turn spiral 100 (the lower right corner of second spiral 104).

[0048] FIG. 5 illustrates one embodiment of a multi-turn spiral 100 including one or more wires configured to annihilate at least two domain walls of the multi-turn spiral 100, according to aspects of the present disclosure. The one or more wires can include a remagnetization component, including a remagnetization coil 120, which can be wrapped around the portion 114 of the multi-turn spiral 100 shown in FIG. 4. The remagnetization coil 120 can be a flat solenoid coil wrapped around the nanowire. The remagnetization coil 120 can include a first wire 122 located below the multi-turn spiral 100 and a second wire 124 located above the multi-turn spiral 100. In some embodiments, the first wire 122 and the second wire 124 can be electrically connected to each other by a via 126 (see FIG. 6). Thus, the remagnetization coil 120 can surround the nanowire 103 by forming a spiral around the nanowire 103. Thus, the remagnetizing coil 120 may include wires 122 and 124 positioned on opposite sides of the multi-turn spiral 100 that are electrically connected to one another. The multi-turn sensor may be configured to apply a current pulse to the remagnetizing coil 120 to remagnetize the portion 114 of the multi-turn spiral 100. For example, a controller (e.g., controller 26 of FIG. 2) may be configured to apply a current pulse to the remagnetizing coil 120.

[0049] Figure 6 shows a portion of the remagnetizing coil 120 with partially transparent layers to show the connections between the layers. In particular, Figure 6 shows a via 126 connecting the first wire 122 to the second wire 124 of the remagnetizing coil 120. A portion of the nanowire 103 that forms the multi-turn spiral 100 is also shown between the first wire 122 and the second wire 124 of the remagnetizing coil 120.

[0050] FIG. 7 illustrates the direction of current flowing through the remagnetizing coil 120 when applied with a current pulse 130, according to aspects of the present disclosure. In some embodiments, it may be important to apply the current pulse to the remagnetizing coil 120 for a relatively short period of time. For example, the current pulse may be applied for a length of time on the order of 1 microsecond. Referring to FIG. 7 , in the illustrated embodiment, the current pulse 130 is applied between the ends of the remagnetizing coil 120 to generate a magnetic field 132 along the portion 114 of the multi-turn spiral 100 that overlaps the remagnetizing coil 120. Compared to the magnetization of the portion 114 of the multi-turn spiral 100 indicated by the arrows in FIGS. 1 and 3 , the magnetic field 132 generated by the current pulse 130 is oriented in the opposite direction. When the magnetic field 132 has a sufficient magnitude (e.g., greater than a threshold magnetic field), the magnetic field 132 remagnetizes the portion 114 of the multi-turn spiral 100.

[0051] Figure 7 also shows the direction of the magnetic field 110 applied during the stage of the initialization process shown in Figure 3. As shown in Figure 7, the direction of the magnetic field 132 is substantially opposite to the direction of the magnetic field 110 and, consequently, the pair of domain walls 112 (see tail-to-tail domain wall 112a and head-to-head domain wall 112b in Figure 4).

[0052] FIG. 8 illustrates the magnetization of the multi-turn spiral 100 after the remagnetization of FIG. 7 , according to an embodiment of the present disclosure. The domain wall 112 previously present in the portion 114 of the multi-turn spiral 100 is removed (e.g., via annihilation), and the magnetization / domain is rotated by 180 degrees. Using this domain wall gap in the domain walls shown in FIG. 8 , compared to the configuration of FIG. 3 , the multi-turn spiral 100 can be initialized at an intermediate position (e.g., a position between the minimum and maximum turn count). The multi-turn sensor can determine the location of the first missing domain wall pair along the multi-turn spiral 100 starting from the domain wall generator 106, for example, by measuring the resistance of the nanowire (whether the nanowire is implemented using GMR, tunneling magnetoresistance (TMR), or another technology). The multi-turn sensor can then determine the turn count based on the determined location of the first missing domain wall pair.

[0053] Although certain embodiments are discussed with reference to initialization, any suitable principles and advantages disclosed herein may be applied to setting the state of a multi-turn spiral at one or more other times. For example, any suitable principles and advantages disclosed herein may be applied to a power-down situation. As another example, any suitable principles and advantages disclosed herein may be applied to rollover counting. Rollover counting may enable a multi-turn sensor system to count turns beyond the number of turns of a multi-turn spiral. In rollover counting, the multi-turn spiral may be set to a particular state (e.g., an intermediate stage) after reaching a particular turn count (e.g., a maximum or minimum turn count), a turn count index may be stored and / or updated, and a readout circuit may determine the turn count based on the stored turn count index and the state of the multi-turn spiral.

[0054] 5 and 8 illustrate one embodiment in which the remagnetizing coil 120 extends along the portion 114 of the multi-turn spiral 100, the remagnetizing coil 120 may be located along any other suitable portion of the multi-turn spiral 100 without departing from aspects of the present disclosure. Thus, the multi-turn spiral 100 may be reset at different points along the multi-turn spiral 100 depending on the location of the remagnetizing coil 120. In further embodiments, multiple coils 120 may be included at different locations along the multi-turn spiral 100, allowing the multi-turn sensor to initialize the multi-turn spiral 100 to multiple different turn count states.

[0055] FIG. 9 illustrates an exemplary cross section of a multi-turn spiral 100 according to an embodiment of the present disclosure. As shown in FIG. 9, the multi-turn spiral 100 includes a silicon wafer 140 having a silicon oxide (SiO) surface 142, a first isolation layer 144, a second isolation layer 146, a third isolation layer 148, a first metal layer 150, a nanowire layer 152, a first via layer 154, a second via layer 156, and a second metal layer 158. In some embodiments, the first metal layer 150 and the second metal layer 158 may be formed of Al, Au, Cu, alloys thereof, or any other suitable metal used for semiconductor wires. The first, second, and third isolation layers 144, 146, and 148 may be formed of AlO, SiN, or similar electrically isolating materials. The third isolation layer 148 may be a final passivation layer. The first via layer 154 and the second via layer 156 can electrically connect the first metal layer 150 and the second metal layer 158. The remagnetization coil 120 can be formed by the first metal layer 150 and the second metal layer 158 and the electrical connections provided by the first via layer 154 and the second via layer 156. The nanowire layer 152 can be formed of a GMR and / or TMR material.

[0056] Those skilled in the art will appreciate that the arrangement shown in FIG. 9 is just one embodiment of the multi-turn spiral 100, and that the multi-turn spiral 100 can be implemented in a variety of different ways.

[0057] FIG. 10 illustrates another embodiment of a multi-turn spiral 100 including a remagnetizing component that can be used to remagnetize a portion of the multi-turn spiral 100, according to aspects of the present disclosure. In contrast to the embodiment of FIG. 5, the remagnetizing component of the embodiment of FIG. 10 includes a remagnetizing coil 120 that covers a larger portion of the multi-turn spiral 100. For example, the remagnetizing coil 120 can cover a complete turn of the multi-turn spiral 100. FIG. 10 illustrates an exemplary remagnetizing coil 120 that covers a complete turn of the multi-turn spiral 100.

[0058] When the multi-turn spiral 100 is filled with domain walls 112, the locations of the domain walls may change due to, for example, the magnetic field 110. Referring back to FIG. 3, the multi-turn spiral 100 may be filled with domain walls 112, with the domain walls 112 located at the upper left and lower right corners of the multi-turn spiral 100. However, if the magnetic field 110 is rotated approximately 90 degrees in either direction, the domain walls 112 should be located at the lower left and upper right corners of the multi-turn spiral 100. In this case, the remagnetization coil 120 of FIG. 5 will only cover a single domain wall and may therefore not be able to annihilate the pair of domain walls.

[0059] In contrast, the multi-turn spiral 100 of FIG. 10 includes a remagnetizing coil 120 that covers a complete turn of the multi-turn spiral 100. Therefore, the remagnetizing coil 120 will cover at least two domain walls 112, regardless of the orientation of the external magnetic field 110. Therefore, the multi-turn spiral 100 can more reliably annihilate pairs of domain walls 112 in the area covered by the remagnetizing coil 120. The multi-turn sensor can also be configured to apply a current pulse to the remagnetizing coil 120 in either direction to ensure that domain walls 112 located within the remagnetizing coil 120 can annihilate. A remagnetizing coil 120 that covers three-quarters of the turns of a multi-turn magnetic sensor can be sufficient to annihilate domain wall pairs under any operating magnetic field.

[0060] 11 illustrates an exemplary method 200 for initializing the multi-turn spiral 100 according to an embodiment of the present disclosure. The method 200 begins at block 201.

[0061] In block 202, the multi-turn sensor system applies a magnetic field to the multi-turn spiral 100 having a strength sufficient to fill the multi-turn spiral 100 with domain walls. In some embodiments, the multi-turn sensor system can apply the magnetic field using a reset coil (such as magnetic reset 27 in FIG. 2) or a reset wire (such as reset wire 160 in FIG. 13). The multi-turn sensor system applies the magnetic field to the multi-turn spiral 100 in the presence of an operating magnetic field, which may be generated by a magnet, such as magnetic target 21 in FIG. 2. In some cases, the operating magnetic field may have any direction; therefore, the strength of the magnetic field applied to the multi-turn spiral 100 may exceed a threshold that can fill the multi-turn spiral 100 with domain walls, regardless of the direction of the operating magnetic field.

[0062] In block 204, the multi-turn sensor system applies a current pulse to the remagnetization coil 120 to remove at least one pair of domain walls in the multi-turn spiral 100. The method 200 ends in block 206. At this point, the multi-turn spiral 100 is set to a state corresponding to a turn count that is between the ends of the turn count range. Thus, the multi-turn spiral 100 can change state from the state set by the method 200 in response to a rotation of the magnetic field in either the CW or CCW direction.

[0063] 12 illustrates another exemplary method 220 for initializing a multi-turn spiral 100 according to an embodiment of the present disclosure. The method 220 begins at block 221.

[0064] In block 222, the multi-turn sensor system measures the direction of the operating magnetic field. For example, the operating magnetic field may be generated by a magnet, such as magnetic target 21 in FIG. 2. In some embodiments, the multi-turn sensor system may include a single-turn sensor configured to measure the direction or angle of the operating magnetic field. The single-turn sensor may include a quadrant detector combined with an anisotropic magnetoresistive (AMR) sensor.

[0065] In block 224, the multi-turn sensor system determines a direction for applying a current pulse to a reset coil (such as magnetic reset 27 in FIG. 2) or reset wire (such as reset wire 160 in FIG. 13) to fill the multi-turn spiral 100 with domain walls. The multi-turn sensor system applies a current pulse to the remaining coils or wires based on the determined direction of the external magnetic field from block 222. The magnitude of the current pulse is selected to generate a magnetic field with sufficient strength to fill the multi-turn spiral 100 with domain walls.

[0066] At block 226, the multi-turn sensor system applies a current pulse to the remagnetizing coil 120 to remove at least one pair of domain walls in the multi-turn spiral 100. As at block 224, the multi-turn sensor system can determine a direction to apply the current pulse to the remagnetizing coil 120 based on the determined direction of the external magnetic field from block 222. The method 220 ends at block 228.

[0067] Advantageously, by measuring the external magnetic field direction in block 222, the magnitude of the current pulses applied to both the reset coil and the remagnetization coil 120 can be reduced. That is, the multi-turn sensor system can apply current pulses in a direction that combines constructively with the external magnetic field direction. In contrast, if the direction of the external magnetic field is unknown, the magnitude of the current pulses must generate a magnetic field sufficient to overcome the external magnetic field when it is opposite the generated magnetic field, causing the multi-turn spiral 100 to fill with domain walls or annihilate domain wall pairs.

[0068] In either or both of methods 200 or 220, rather than applying a magnetic field to the multi-turn spiral 100 relative to a magnetic target to fill the multi-turn spiral 100 with domain walls, the sensor fills the multi-turn spiral 100 in blocks 202 and / or 224 by mechanically rotating the applied magnetic field (e.g., magnetic target 21 of FIG. 2 ), so that the domain walls from the domain wall generator 106 can propagate around the multi-turn spiral 100 until the multi-turn spiral 100 is filled with domain walls. The mechanical rotation of the applied magnetic field can be in a CW or CCW direction, depending on the location of the domain wall generator 106 and the spiral direction of the multi-turn spiral 100.

[0069] In some embodiments, the location of the gap in the domain wall (e.g., the location where the annihilated domain wall was expected to be located) can be moved by rotating the magnetic field in the remagnetization coil with an applied current pulse in combination with providing a custom domain wall configuration pattern in the spiral after initialization of method 200 and / or method 220 is complete. In some embodiments, one or more additional domain wall pairs can be annihilated to form multiple gaps in the domain wall when providing a custom domain wall configuration pattern. For example, the additional domain wall pairs can be annihilated after moving the additional domain wall pairs in the portion of the multi-turn spiral 100 corresponding to the remagnetization coil 120. In some embodiments, the multi-turn spiral 100 can include multiple remagnetization coils 120 positioned in different portions of the multi-turn spiral 100, and each of the remagnetization coils 120 can be configured to annihilate one or more pairs of domain walls.

[0070] In some embodiments, the sensor can also use measurements from a readout circuit (such as readout circuit 28 of FIG. 2) as part of the initialization process (e.g., methods 200 and / or 220). The readout circuit can generate a resistance readout that can be used to measure the magnetization state of each of the spirals 102 and 104 of the multi-turn spiral 100. This output from the readout circuit can be used in a number of ways for the initialization process.

[0071] For example, the multi-turn sensor system can measure the magnetization state of each of spirals 102 and 104 before and after remagnetization (e.g., blocks 204 and 226) of portion 114 of multi-turn spiral 100. The multi-turn sensor system can verify that multi-turn spiral 100 is filled with domain walls before remagnetization, and verify that a pair of domain walls has disappeared after remagnetization.

[0072] In some embodiments, in response to detecting that the remagnetization process has failed, the multi-turn sensor system may repeat the remagnetization process (e.g., repeat block 204 or 226) or apply a current pulse to the remagnetization coil 120 with a current of a larger magnitude.

[0073] In some embodiments, in response to detecting that the remagnetization process has failed, the multi-turn sensor system may report the failed remagnetization as part of a self-diagnosis of the multi-turn sensor system.

[0074] In some embodiments, the multi-turn sensor system can determine the location of the vanishing pair of domain walls based on the measured magnetization state of the spiral, and then energize only selected portions of the remagnetization coil 120 where the vanishing pair of domain walls are located.

[0075] In some embodiments, the multi-turn sensor system can energize only selected portions of the remagnetization coil 120 based on the determined locations of the pair of domain walls, allowing the external magnetic field to move the domain walls when the direction of the external magnetic field moves the domain walls in a desired direction for annihilation.

[0076] In some embodiments, the multi-turn sensor system can energize selected portions of the remagnetization coil 120 with a current of a larger magnitude based on the determined locations of a pair of domain walls, for example, when moving the domain walls in a direction opposite to the external magnetic field. This can ensure that the magnetic field applied by the remagnetization coil 120 is sufficient to overcome the external magnetic field while also moving the domain walls in the desired direction for annihilation.

[0077] In some embodiments, multi-turn sensors including the multi-turn spirals described herein can be implemented using GMR technology. The GMR multi-turn sensor may be combined with a magnetic field angle sensor and / or sensors configured to measure magnetic field amplitude. These sensors may be fabricated at the system level on the same die as the GMR multi-turn sensor, on a co-packaged die, or on the same printed circuit board (PCB). These sensors can be based on AMR, GMR, TMR, and / or Hall effect technology. The multi-turn sensor can use the output from these sensors to remagnetize the multi-turn spiral segments in a manner similar to how the output of the readout circuit is used, as described above. For example, a remagnetizing current can be applied to a selected number of segments of the remagnetizing coil 120. In other segments of the remagnetizing coil 120, the domain walls will move due to an external magnetic field. In other cases, the remagnetizing current amplitude of each segment of the remagnetizing coil 120 can be adjusted depending on the strength and direction of the measured external magnetic field.

[0078] FIG. 13 illustrates another embodiment of a multi-turn spiral 100 including a magnetization component that can be used to fill the multi-turn spiral 100 with domain walls, according to aspects of the present disclosure. In the embodiment of FIG. 13, the magnetization component includes a pair of reset wires 160 disposed across both the first spiral 102 and the second spiral 104 of the multi-turn spiral 100. In other embodiments, the magnetization component can include one or more domain wall generators configured to provide domain walls in one or both of the first spiral 102 and the second spiral 104. The reset wire 160 can be combined with a remagnetization coil 120 and monolithically integrated with the multi-turn spiral 100. The reset wire 160 can fill the multi-turn spiral 100 with domain walls. While FIG. 13 illustrates an embodiment in which the reset wire 160 is embodied as a wire, in other embodiments, the reset wire 160 can be replaced with a reset coil configured to fill the multi-turn spiral 100 with domain walls.

[0079] While certain embodiments include open-loop spirals, any suitable principles and advantages disclosed herein may be applied to closed-loop spirals for multi-turn magnetic sensing. Figure 14 illustrates another embodiment of a multi-turn spiral 300 according to aspects of the present disclosure. Figure 15A illustrates an embodiment of a multi-turn counter loop 340 according to aspects of the present disclosure. Figure 15B illustrates another embodiment of a multi-turn counter loop 360 according to aspects of the present disclosure. Figure 15C illustrates yet another embodiment of a multi-turn counter loop 380 according to aspects of the present disclosure.

[0080] 14 , multi-turn spiral 300 can include nanowires 303 formed in a closed-loop spiral. In some embodiments, closed-loop multi-turn spiral 300 can include a siphon structure or bridge to allow domain walls to continuously propagate around multi-turn spiral 300. A remagnetizing component (not shown in FIG. 14 ) can be positioned such that the remagnetizing component can magnetize portion 314 of multi-turn spiral 300 to annihilate the pair of domain walls. The remagnetizing component can be, for example, a remagnetizing coil. The remagnetizing component can be embodied according to any suitable principles and advantages described herein.

[0081] In FIG. 15A , the multi-turn counter loop 340 can include a nanowire 343 formed in a closed loop with multiple stop structures 356, sometimes referred to as inwardly tapered protrusions. The multiple stop structures 356 can be implemented according to any suitable principles and advantages disclosed in U.S. Patent Publication No. 2010 / 0301842, the disclosure of which is incorporated herein by reference in its entirety for all purposes. In some embodiments, the closed-loop multi-turn counter loop 340 can include a partition structure to allow a domain wall to propagate continuously around the multi-turn counter loop 340. A remagnetization component (not shown) can be positioned such that the remagnetization component magnetizes a portion 354 of the multi-turn counter loop 340 to annihilate a pair of domain walls. The remagnetization component can be, for example, a remagnetization wire or a remagnetization coil. The remagnetization component can be embodied according to any suitable principles and advantages described herein.

[0082] 15B and 15C, the multi-turn counter loops 360, 380 can have other structures configured to detect the turn count of the operating magnetic field. A remagnetization component (not shown) can be positioned such that the remagnetization component can magnetize a portion of the multi-turn counter loops 360, 380 to annihilate a pair of domain walls. The remagnetization component can be, for example, a remagnetization wire or a remagnetization coil. The remagnetization component can be embodied according to any suitable principles and advantages described herein.

[0083] While certain embodiments include one domain wall generator connected to the end of a multi-turn spiral, any suitable principles and advantages disclosed herein may be applied to multi-turn spirals that are connected to no domain wall generators or to two or more domain wall generators. Figure 16 illustrates yet another embodiment of a multi-turn spiral 400 according to aspects of the present disclosure. Figure 17 illustrates another embodiment of a multi-turn spiral 440 according to aspects of the present disclosure.

[0084] 16, the multi-turn spiral 400 can include a first spiral 402 and a second spiral 404 coupled together such that a domain wall can propagate between the first spiral 402 and the second spiral 404. The first spiral 402 and the second spiral 404 can be formed from a nanowire 403. The multi-turn spiral 400 of FIG. 16 does not include a domain wall generator.

[0085] 16, for an open-loop multi-turn spiral 400 without a domain wall generator, it may be desirable to ensure that at least one domain wall remains adjacent to the domain wall gap created by remagnetization. For example, overturning the multi-turn spiral 400 in either the CW or CCW direction could remove one of the domain walls adjacent to the domain wall gap, obscuring the turn count information. Therefore, avoiding such overturning can be advantageous.

[0086] 17, a multi-turn spiral 440 can include a first spiral 402 and a second spiral 404 coupled together such that a domain wall can propagate between the first spiral 402 and the second spiral 404. The first spiral 402 and the second spiral 404 can be formed from a nanowire 403. The multi-turn spiral 440 of FIG. 17 also includes a pair of domain wall generators 446 at opposite ends of the multi-turn spiral 440.

[0087] 17, it may be desirable to ensure that the domain wall gap does not fall into either of the domain wall generators 446. Overturning in the CW or CCW direction can fill the domain wall gap with a new domain wall, and the turn count information may become ambiguous. Therefore, it may be advantageous to avoid such overturning.

[0088] For example, in the case of an open-loop spiral with one domain wall generator 106, as shown in FIG. 1 , it may be desirable to ensure that the domain wall gap on the domain wall generator 106 side does not enter the domain wall generator 106. If the domain wall gap enters the domain wall generator 106, the gap may be filled with a new domain wall, and the turn count information would become ambiguous. The end without the domain wall generator 106 may be allowed to rotate until the domain wall gap disappears at this end, but it cannot rotate any further. It is desirable not to push the domain wall adjacent to the gap on the domain wall generator side out of the multi-turn spiral 100. Overturning would result in erroneous turn count information. Therefore, it may be advantageous to avoid such overturning.

[0089] In certain embodiments, the remagnetization component can be divided into sections that can be energized to annihilate domain walls. The sections can be connected in parallel to one another. FIG. 18 illustrates another embodiment of a multi-turn spiral 500 including one or more wires configured to annihilate at least two domain walls of the multi-turn spiral 500, according to aspects of the present disclosure. In contrast to the embodiments of FIGS. 5 and 10 , the one or more wires in FIG. 18 include a remagnetization coil 520 having multiple sections 522, the selection of which is numbered in FIG. 18 . The sections 522 of the remagnetization coil 520 can be energized in sequence to move pairs of domain walls toward one another and annihilate them when they meet. For example, the sequence can include applying current pulses to sections 1 and N-1, sections 2 and N-2, sections 3 and N-3, etc. In some embodiments, current pulses can be applied such that adjacent sections 522 are energized with at least some overlap. For example, sections 2 and N-2 can be energized before sections 1 and N are de-energized.

[0090] In embodiments where the multi-turn sensor system measures the direction of an external magnetic field, because domain walls may propagate due to the applied external magnetic field, the multi-turn sensor system may not energize certain sections 522 of the remagnetization coil 520. This may reduce the power used to annihilate a pair of domain walls.

[0091] By using a remagnetizing coil 520 with multiple sections 522, the total amount of current applied to the multiple sections 522 can be smaller than the current pulse applied to a single remagnetizing coil (such as the remagnetizing coil 120 of FIG. 5 or FIG. 10 ). For example, when using a single coil as the remagnetizing coil, the coil resistance may be relatively high. Therefore, to overcome the coil resistance, a relatively high voltage may be used for the current pulse. In some implementations, the magnitude of the current pulse may be difficult to generate using the supply voltage available on a multi-turn sensor system. Therefore, using a remagnetizing coil 520 with multiple sections 522 may be more practical in embodiments with limited supply voltage.

[0092] In some embodiments, multiple sections 522 can be electrically connected in parallel, thereby reducing the total resistance and increasing the total current to remagnetize the desired spiral region.

[0093] While certain embodiments include a remagnetizing coil, any other suitable remagnetizing component can alternatively or additionally be used to annihilate the domain walls. FIG. 19 illustrates yet another embodiment of a multi-turn spiral 600 including one or more wires forming a remagnetizing component 620 that can be used to remagnetize a portion of the multi-turn spiral 600, according to aspects of the present disclosure. In contrast to the embodiment of FIG. 18, the remagnetizing component 620 includes multiple metal sections 622, the selection of which is numbered in FIG. 19. As illustrated, the multiple metal sections 622 can be present in a single layer. The multiple metal sections 622 can be located adjacent to the nanowire 603, for example, above or below the nanowire 603, forming the multi-turn spiral 600. Advantageously, fabricating a remagnetizing component 620 with multiple metal sections 622 in a single layer can have simpler process integration than embodiments employing a spiral coil wound around the nanowire 603. In certain applications, a spiral coil wrapped around nanowire 603 may be more efficient at generating a magnetic field compared to multiple metal sections 622 on one side of nanowire 603.

[0094] In some embodiments, the plurality of metal sections 622 can be spaced a predetermined distance from the nanowire 603. For example, the predetermined distance can be selected to ensure that the plurality of metal sections 622 are sufficiently close to the nanowire 603 to generate a magnetic field at the nanowire 603 with sufficient strength, while also allowing the plurality of metal sections 622 to be spaced far enough from the nanowire 603 to ensure that the plurality of metal sections 622 are not shorted to the nanowire 603, for example, as a result of manufacturing deformations.

[0095] In some embodiments, multiple metal sections 622 can be connected in parallel with one another. In other embodiments, multiple metal sections 622 can be energized in a sequential order, similar to the sequential order described in connection with FIG. 18 .

[0096] FIG. 20 illustrates yet another embodiment of a multi-turn spiral 700 including a remagnetizing component that can be used to remagnetize a portion of the multi-turn spiral 700, according to aspects of the present disclosure. In contrast to the embodiments of FIGS. 5 and 10, the remagnetizing component includes a remagnetizing coil 720 formed on one side (e.g., above or below) of the nanowire 703. The remagnetizing coil 720 includes a plurality of first wires 722 and a plurality of second wires 724 positioned above the first wires 722. In the embodiment of FIG. 20, in which the remagnetizing coil 720 is positioned above the nanowire 703, the first wires 722 can generate a magnetic field to annihilate a pair of domain walls. The second wires 724 may not significantly affect the magnetic field generated by the first wires 722. For example, the second wires 724 may generate a Coulter field on the nanowire 703 that has a lower magnitude due to their greater distance from the nanowire 703.

[0097] 21 illustrates an exemplary method 800 for initializing a multi-turn magnetic sensing system according to an embodiment of the present disclosure. The method 800 begins at block 801.

[0098] At block 810, the method 800 includes filling the multi-turn spiral with a domain wall. For example, a multi-turn magnetic sensing system may include a magnetizing component configured to fill the multi-turn spiral with a domain wall.

[0099] At block 820, the method 800 includes remagnetizing a portion of the multi-turn spiral to annihilate at least two of the domain walls of the multi-turn spiral. For example, the multi-turn magnetic sensing system may include a remagnetization component configured to generate a magnetic field across the portion of the multi-turn spiral to annihilate domain walls within the portion of the multi-turn spiral. The remagnetization component may be implemented according to any suitable principles and advantages disclosed herein.

[0100] At block 830, the method 800 includes measuring the turn count based on the output signal from the multi-turn spiral. For example, the multi-turn magnetic sensing system may include a decoder configured to determine the turn count based on the location of the domain wall gap formed by the annihilation of at least two of the domain walls. The method 800 ends at block 840.

[0101] Intermediate position reset for multi-turn magnetic sensors Aspects of the present disclosure relate to resetting a multi-turn magnetic sensor to a reset state corresponding to a turn count between a first value and a second value of a turn count range corresponding to two multi-turn magnetic sensor states. The first value can be a minimum value of the turn count range, and the second value can be a maximum value of the turn count range. Thus, the multi-turn magnetic sensing system can track a CW rotation of a magnetic field from the reset state and track a CCW rotation of a magnetic field from the reset state.

[0102] In some embodiments, the multi-turn magnetic sensing system can include two multi-turn magnetic sensors, one CW multi-turn magnetic sensor, and one CCW multi-turn magnetic sensor. Domain walls can propagate in opposite directions in the CW multi-turn sensor and the CCW multi-turn magnetic sensor. Both the CW multi-turn magnetic sensor and the CCW multi-turn magnetic sensor can be reset to a reset state during an initialization phase. The reset state can correspond to both multi-turn magnetic sensors being filled with domain walls.

[0103] From the reset state, the multi-turn magnetic sensing system can count the cumulative number of turns in the CW and / or CCW directions. When the magnetic field rotates in the CW direction from the reset state, the CCW sensor counts down from N to 0, where N is the maximum number of turns. At the same time, the CW sensor can remain in its maximum N-turn state. Similarly, when the magnetic field rotates in the CCW direction from the reset state, the CW sensor can count down from N to 0, where N is the maximum number of turns. At the same time, the CCW sensor can remain in its maximum N-turn state.

[0104] Figure 22A is a schematic diagram of two multi-turn sensors of a multi-turn magnetic sensing system according to one embodiment. Figure 22B is a table summarizing the states and turn counts for the multi-turn magnetic sensing system of Figure 22A as the magnetic field rotates. Figure 22A shows a multi-turn magnetic sensing system 10 having a CW sensor and a CCW sensor with magnetic reset capability capable of measuring ±N rotations of a rotating magnetic field with a mid-range magnetic reset.

[0105] Referring to FIG. 22A , a multi-turn magnetic sensing system 10 includes a first magnetic spiral 12 and a second magnetic spiral 14. The magnetic spirals 12 and 14 each implement a respective multi-turn magnetic sensor. The magnetic spirals 12 and 14 each include a plurality of magnetoresistive elements 15 arranged in series with each other. Each side of the magnetic spirals 12 and 14 between adjacent corners of the magnetic spirals 12 and 14 includes a magnetoresistive element 15. The magnetic spirals 12 and 14 each include 6 turns and 24 magnetoresistive elements 15. The magnetic spirals 12 and 14 may each include a domain wall generator 16 at the end of the spiral. In certain applications, the first magnetic spiral 12 and the second magnetic spiral 14 can exist on a single die. Alternatively, the first magnetic spiral 12 and the second magnetic spiral 14 can exist on different dies.

[0106] The multi-turn magnetic sensing system 10 can count ±3 turns of the magnetic field from the reset state. The reset state can correspond to a turn count between the endpoints of the counting range. For example, in the multi-turn magnetic sensing system 10, the reset state can correspond to the midpoint of the counting range. For a ±3 count range, the first magnetic spiral 12 and the second magnetic spiral 14 can each have a measurement range of 6 turns. For example, as shown in FIG. 22A , the first magnetic spiral 12 can count 6 turns of the magnetic field in the CW direction, and the second magnetic spiral 14 can count 6 turns of the magnetic field in the CCW direction. In the multi-turn magnetic sensing system 10, the reset state can correspond to the midpoint of the turn count range. This can be because the first magnetic spiral 12 and the second magnetic spiral 14 have the same number of turns.

[0107] In this disclosure, CW turns are denoted as positive turns and CCW turns are denoted as negative turns. The same functions can be described using the opposite convention, where CCW turns are positive turns and CW turns are negative turns.

[0108] The operation of the multi-turn magnetic sensing system 10 will be discussed with reference to FIG. 22B. The first magnetic spiral 12 and the second magnetic spiral 14 can be reset. This can fill each of the magnetic spirals 12, 14 with a domain wall. In the reset state, the first magnetic spiral 12 and the second magnetic spiral 14 can both be in a maximum state, which in this example is 6. The turn count of the multi-turn magnetic sensing system 10 can represent the cumulative number of turns since the reset state. Thus, in the reset state, the turn count is 0. This state can be system state A of the multi-turn magnetic sensing system 10.

[0109] As the magnetic field rotates three full CW turns, the turn count of the second magnetic spiral 14 may decrease and the state of the first magnetic spiral 12 may remain the same. The turn count of the multi-turn magnetic sensing system 10 may increase by one for each full CW rotation of the magnetic field. The states of the multi-turn magnetic sensing system 10 after one full CW rotation from the reset state, two full CW rotations from the reset state, and three full CW rotations from the reset state are B, C, and D, respectively, in FIG. 22B .

[0110] As the magnetic field rotates three full CW turns, the turn count of the second magnetic spiral 14 may decrease and the turn count of the first magnetic spiral 12 may remain the same. The turn count of the multi-turn magnetic sensing system 10 may increase by one for each full CW rotation of the magnetic field. The states of the multi-turn magnetic sensing system 10 after one full CW rotation from the reset state, two full CW rotations from the reset state, and three full CW rotations from the reset state are B, C, and D, respectively, in FIG. 22B .

[0111] From system state D, the magnetic field can rotate three full CCW turns. The turn count of the first magnetic spiral 12 can decrease and the turn count of the second magnetic spiral 14 can increase. The turn count of the multi-turn magnetic sensing system 10 can decrease by one for each full CCW rotation of the magnetic field. The states of the multi-turn magnetic sensing system 10 after these full CCW magnetic field rotations from system state D are E, F, and G, respectively. In system state G, after three CW rotations and three CCW rotations from the reset state, the system turn count returns to 0.

[0112] The magnetic field can be rotated three more full CW turns, where the first magnetic spiral 12 can be decreased and the turn count of the second magnetic spiral 14 can be increased.

[0113] After the magnetic field has rotated three cumulative turns in each direction from the reset state, the multi-turn magnetic sensing system 10 can operate in a balanced state. The first system state K and subsequent states in FIG. 22B correspond to the multi-turn magnetic sensing system 10 operating in a balanced state. Once equilibrium is reached, the multi-turn magnetic sensing system 10 operates in one of seven system states for a full turn of the magnetic field, where these system states correspond to full turn counts from -3 to +3. These seven system states are states J, K, L, M, N, O, and P in FIG. 22B. A preconditioning circuit and decoder can be used to decode the valid pre-balanced states into turn counts. In FIG. 22B, states A, B, C, D, E, F, G, H, and I are valid pre-balanced states from which the system turn count can be decoded.

[0114] As shown by FIG. 22B , the multi-turn magnetic sensing system 10 can have two or more system states corresponding to the same turn count. For example, there may be a pre-equilibrium state and an equilibrium state that both correspond to the same turn count. As an example, system states H and L both correspond to a turn count of −1. As another example, system states B, F, and N each correspond to a turn count of 1. This example shows that two or more pre-equilibrium states can correspond to the same turn count as one equilibrium state.

[0115] 22B shows 16 system states (i.e., states A through P) corresponding to full turns from the reset state. Other valid states are possible for the multi-turn magnetic sensing system 10. Another valid state may be a pre-balance state. As an example of another valid state, one CCW rotation from the reset state may be another valid state.

[0116] The operation of the multi-turn magnetic sensing system 10 is discussed above with reference to a full rotation of the magnetic field. The multi-turn magnetic sensing system 10 can track turns at different resolutions according to any suitable principles and advantages disclosed herein. For example, the decoder can determine turn counts from output signals associated with the first magnetic spiral 12 and / or the second magnetic spiral 14 with half-turn or quarter-turn resolution. With half-turn resolution, an intermediate state can exist between any two consecutive states associated with a full turn, where the intermediate state can correspond to a half-turn between two consecutive full-turn states. With quarter-turn resolution, three intermediate states can exist between any two consecutive states associated with a full turn, where the intermediate states can correspond to a quarter-turn, a half-turn, and three-quarters turn.

[0117] 22A and / or 22B may be applied to a multi-turn magnetic sensing system capable of counting ±N turns, where the CW and CCW sensors each have an individual measurement range of 2N turns. For rollover counting and indexing, any suitable principles and advantages disclosed with reference to FIGURES 22A and / or 22B may be applied to a multi-turn magnetic sensing system with rollover counting, where the turn count may have a value having a magnitude greater than the number of turns of an individual multi-turn magnetic sensor.

[0118] Although magnetic spirals 12 and 14 are configured to count the same number of turns, any of the suitable principles and advantages disclosed with reference to Figures 22A and / or 22B may be applied to two magnetic spirals capable of counting different numbers of turns, in which case the reset state need not be at the exact midpoint of the system turn count range.

[0119] Uses, Terminology, and Conclusions The multi-turn magnetic sensing systems disclosed herein can be implemented in any suitable application that can benefit from counting turns of a rotating magnetic field. Example applications include, but are not limited to, electronic power steering (EPS) applications such as EPS steer-by-wire actuator applications, parking lock actuators, seat belt retractors, transmission actuators, other vehicle applications, robotics and / or robotic applications such as arm joint position tracking, rotary to linear actuator applications, wire draw encoder applications, other industrial automation applications, etc.

[0120] In the embodiments described above, sensors, circuits, systems, and methods for multi-turn magnetic sensing are described with reference to specific embodiments. However, it will be understood that the principles and advantages of the embodiments may be used for any other suitable sensors, circuits, systems, and methods involving multi-turn magnetic sensing.

[0121] Unless the context clearly requires otherwise, throughout the specification and claims, words such as "comprise," "comprising," "include," "including," and the like, should be construed in an inclusive sense, i.e., "including, but not limited to," as opposed to an exclusive or exhaustive sense. As generally used herein, the words "coupled" or "connected" refer to two or more elements, which may be directly connected or connected via one or more intermediate elements. Thus, the various schematic diagrams shown in the figures depict example configurations of elements and components, although additional intervening elements, devices, features, or components may be present in an actual embodiment (provided the functionality of the depicted circuitry is not adversely affected). Furthermore, the words "herein," "above," "below," and words of similar import, when used herein, shall refer to this specification as a whole and not to any particular portions of this specification. Where the context permits, words in the detailed description using singular or plural numerals may also include the plural or singular numerals, respectively. The word "or" when referring to a list of two or more items is intended to encompass all interpretations of the word: any item in the list, all items in the list, and combinations of items in the list. All numerical values ​​provided herein are intended to include similar values ​​within the error of measurement.

[0122] Additionally, conditional language used herein, such as, among others, "can," "could," "might," "may," "for example," "etc.", and the like, unless specifically stated otherwise or understood within the context when used otherwise, is generally intended to convey that certain embodiments include certain features, elements, and / or conditions, while other embodiments do not.

[0123] The teachings of the embodiments provided herein may be applied to other systems, not necessarily those described above. Elements and acts of the various embodiments described above may be combined to provide further embodiments. The acts of the methods discussed herein may be performed in any order, as appropriate. Furthermore, the acts of the methods discussed herein may be performed serially or in parallel, as appropriate.

[0124] While certain embodiments of the present invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel circuits, methods, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the circuits, methods, apparatus, and systems described herein may be made without departing from the spirit of the present disclosure. For example, while the disclosed embodiments are presented in a given configuration, alternative embodiments may perform the same degree of functionality with different components and / or circuit topologies, and some elements may be deleted, moved, added, subdivided, combined, and / or modified. Each of these elements may be implemented in a variety of different ways. Any suitable combination of elements and acts of the various embodiments described above may be combined to provide further embodiments. The following claims and their equivalents are intended to cover such forms or modifications as are within the scope and spirit of the present disclosure. Accordingly, the scope of the present invention is defined by reference to the claims.

[0125] The claims presented herein are in single dependent form for filing with the USPTO, but it should be understood that any claim may depend on any preceding claim of the same type unless it is clearly not technically feasible to do so.

Claims

1. 1. A multi-turn magnetic sensing system, comprising: a multi-turn loop through which a domain wall propagates in response to a rotation of a magnetic field; a magnetizing component configured to provide the domain wall in the multi-turn loop; one or more wires configured to annihilate at least two of the domain walls of the multi-turn loop.

2. The multi-turn magnetic sensing system of claim 1 , wherein the magnetizing component includes a reset wire configured to fill the multi-turn loop with a domain wall.

3. 2. The multi-turn magnetic sensing system of claim 1, further comprising a decoder configured to output a turn count based on an output signal from the multi-turn loop, the decoder configured to determine the turn count based on a location of a domain wall gap formed by the annihilation of the at least two of the domain walls.

4. The multi-turn magnetic sensing system of claim 1 , wherein the one or more wires include a remagnetizing coil encircling a portion of the multi-turn loop.

5. The multi-turn magnetic sensing system of claim 1 , wherein the one or more wires include a remagnetizing component positioned on one side of a portion of the multi-turn loop.

6. The multi-turn magnetic sensing system of claim 1 , wherein the multi-turn loop comprises a multi-turn spiral, and the one or more wires comprise a remagnetizing component that covers at least three-quarters of the turns of the multi-turn spiral.

7. a readout circuit configured to measure the direction of an external magnetic field; 10. The multi-turn magnetic sensing system of claim 1, further comprising: a controller configured to apply a current pulse to the one or more wires with a direction of the current pulse based on the measured external magnetic field.

8. the readout circuitry is further configured to measure a magnetization state of the multi-turn loop; 8. The multi-turn magnetic sensing system of claim 7, wherein the controller is configured to verify that the at least two of the domain walls have disappeared based on the measured magnetization state of the multi-turn loop.

9. the multi-turn loop comprises a multi-turn spiral, and the magnetizing component comprises: a domain wall generator configured to generate a domain wall at one end of the multi-turn spiral; a magnetic target configured to generate an external magnetic field; 2. The multi-turn magnetic sensing system of claim 1, wherein providing a domain wall on the multi-turn spiral comprises rotating the magnetic target relative to the multi-turn spiral such that the domain wall generated by the domain wall generator propagates around the multi-turn spiral.

10. The magnetized component is The multi-turn magnetic sensing system of claim 1 , comprising one or more reset wires configured to generate a magnetic field having sufficient strength to fill the multi-turn loop with the domain wall.

11. 2. The multi-turn magnetic sensing system of claim 1, wherein the multi-turn loop comprises a multi-turn spiral including a first spiral and a second spiral, the first spiral and the second spiral coupled together such that a domain wall can propagate between the first spiral and the second spiral.

12. 10. The multi-turn magnetic sensing system of claim 1, wherein the one or more wires include a remagnetizing component including multiple sections, the multi-turn magnetic sensing system further comprising a controller configured to sequentially apply current pulses to the sections of the remagnetizing component.

13. 1. A method for initializing a multi-turn magnetic sensing system, comprising: providing a domain wall in a multi-turn loop; applying a magnetic field to a portion of the multi-turn loop so as to annihilate at least two of the domain walls of the multi-turn loop; After said applying, the multi-turn loop is configured to change state in response to a rotation of the magnetic field.

14. The method of claim 13 further comprising determining a turn count based on an output signal from the multi-turn loop.

15. The method of claim 14 , wherein said determining is based on a location of a domain wall gap formed by said annihilation of said at least two of said domain walls.

16. The method of claim 13 , wherein the applying is performed using a coil that encircles a portion of the multi-turn loop.

17. 14. The method of claim 13, further comprising measuring a direction of an external magnetic field, and wherein said applying comprises applying a current pulse to the remagnetizing component, the direction of the current pulse being based on the measured external magnetic field.

18. measuring the magnetization state of the multi-turn loop; 14. The method of claim 13, further comprising verifying that the at least two of the domain walls have disappeared based on the measured magnetization state of the multi-turn loop.

19. 14. The method of claim 13, wherein the providing the domain wall in the multi-turn loop is performed using one or more reset wires that generate a magnetic field having sufficient strength to fill the multi-turn loop with the domain wall.

20. 1. A multi-turn magnetic sensing system, comprising: a multi-turn loop through which a domain wall propagates in response to a rotation of a magnetic field; means for annihilating at least two of the domain walls of the multi-turn loop; a decoder configured to output a turn count based on an output signal from the multi-turn loop.

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