Corruption detection and smart reset of ferromagnetic structures in magnetic field sensors

A sensor package includes a magnetic field sensor and a corruption detection and reset subsystem. The magnetic field sensor has a magnetic sense element and a ferromagnetic structure characterized by a baseline magnetic state. The subsystem includes a detector element, a processor, and current carrying structure positioned in proximity to the ferromagnetic structure. Methodology performed by the subsystem entails detecting at the detector element an altered magnetic state of the ferromagnetic structure, where the altered magnetic state differs from the baseline magnetic state. Methodology further entails determining, at the processor, when a reset action is needed in response to the altered magnetic state and applying a reset magnetic field to the ferromagnetic structure to reset the ferromagnetic structure from the altered magnetic state to the baseline magnetic state.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to magnetoelectronic devices. More specifically, the present invention relates to corruption detection and smart reset of a ferromagnetic structure in a magnetic field sensor.

BACKGROUND OF THE INVENTION

Magnetic field sensors are widely used in a number of applications including in, for example, compass, security, and military applications, geophysics and space research, biomagnetism and medical applications, and non-destructive testing. Magnetic field sensors are typically based on semiconductor materials (e.g., Hall sensors, semiconductor magnetoresistors, and so forth) and ferromagnetic materials (e.g., ferromagnetic magnetoresistors, flux concentrators, flux guides, and the like). Other magnetic sensors utilize optical, resonant, and superconducting properties.

DETAILED DESCRIPTION

In overview, embodiments of the present invention entail a magnetic field sensor package that includes a corruption detection and reset subsystem and methodology for detecting corruption of the magnetic state of a ferromagnetic structure and resetting the ferromagnetic structure to a baseline magnetic state. The corruption detection and reset subsystem ensures that the magnetic field sensor is “smart” in that it detects or otherwise anticipates a corrupting magnetic shock event directly and/or detects the effects of the magnetic shock event on the magnetization state of the ferromagnetic structures and/or detects the effects of the magnetic shock event on the output of the magnetic field sensor. The monitored data is analyzed within the subsystem to determine if and went to initiate a reset action. Accordingly, a reset action is applied when a reset is needed, as opposed to triggering periodically on a set schedule or tied to an external event, thereby achieving savings in power consumption.

The instant disclosure is provided to further explain in an enabling fashion the best modes, at the time of the application, of making and using various embodiments in accordance with the present invention. The disclosure is further offered to enhance an understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the invention. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

It should be understood that the use of relational terms, if any, such as first and second, top and bottom, and the like are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, some of the figures may be illustrated using various shading and/or hatching to distinguish the different elements. These different elements may be produced utilizing current and upcoming fabrication techniques. Accordingly, although different shading and/or hatching is utilized in the illustrations, the different elements within the structural layers may be formed out of the same material.

Referring toFIG. 1,FIG. 1shows a simplified block diagram of a prior art sensor package20. Sensor package20may be implemented in any device or system in which magnetic field sensing is required, for example, in electronic compass, security, and military applications, in geophysics and space research applications, in biomagnetism and medical applications, and/or in non-destructive testing. In this example, sensor package20may be adapted to sense a magnetic field along three axes. Hence, sensor package20includes an X-axis magnetic field sensor24, a Y-axis magnetic field sensor26, and a Z-axis magnetic field sensor28. Magnetic field sensors24,26,28may be coupled to, or otherwise in communication with, an application specific integrated circuit (ASIC)30to form sensor package20. ASIC30performs some or all functions including, but not limited to, signal conditioning and data management, stabilization control, bridge/output multiplexing, self-test, electrostatic discharge (ESD) protection, and so forth.

There is a wide variety of magnetic field sensor technologies that have been implemented and made into products. Many of these magnetic field sensor technologies incorporate patterned ferromagnetic structures (generically referred to herein as “flux concentrators”) for various purposes including shielding, flux concentrating, and flux redirecting. A flux concentrator is a ferrous material used to increase the performance of a magnetic field sensor.

FIG. 2shows a simplified view of a ferromagnetic structure, in the form of a flux concentrator32, implemented with a magnetic field sensor to sense the magnetic field in a direction parallel to the plane of a substrate, such as X-axis magnetic field sensor24. When flux concentrator32is placed opposite a pole face of magnetic field sensor24, an X-axis magnetic field34(represented by dashed lines) channels through flux concentrator32, thereby increasing the magnetic flux density (i.e., the magnetic field) between flux concentrator32and the pole face of magnetic field sensor24. In this side view illustration, an X-axis36is oriented right-and-left on the page, a Y-axis38is oriented up-and-down on the page, and a Z-axis40is represented as a dot that depicts an axis going either into or out of the page on whichFIG. 2is situated. Accordingly, the X-Y plane in this side view illustration is oriented right-and-left and up-and-down on the page.

FIG. 3shows a simplified side view of ferromagnetic structures, in the form of flux guides42, implemented with a magnetic field sensor, such as Z-axis magnetic field sensor28. In this simplified illustration, Z-axis magnetic field sensor28includes a pair of Z-axis sense elements44formed within a dielectric material, or substrate46. Z-axis sense elements44may be magnetic tunnel junction (MTJ) structures, each of which includes ferromagnetic layers48,50separated by an insulator layer52. In this side view illustration, Z-axis40is oriented up-and-down on the page, X-axis36is oriented right-and-left on the page, and Y-axis40is represented as a dot that depicts an axis going either into or out of the page on whichFIG. 2is situated. Accordingly, the X-Y plane in this side view illustration is oriented right-and-left and into or out of the page.

In order to sense the magnetic field in a direction perpendicular to the plane of substrate46, flux guides42are also formed within substrate46. Flux guides42can be used to guide a Z-axis magnetic field54(represented by dashed arrows) into the X-Y plane. Thus, flux guides42are shaped ferromagnetic structures used to guide magnetic flux, i.e., Z-axis magnetic field54, to a preferred location. With the use of flux guides42incorporated into Z-axis magnetic field sensor28, Z-axis magnetic field54is suitably guided so that it can be sensed from in-plane sensing elements (i.e., Z-axis sense elements44).

FIG. 4shows a side view of a ferromagnetic structure, generically referred to herein as a flux concentrator56, exemplifying a magnetic polarization58(represented by rightwardly directed arrows) having a baseline, or stable, orientation. Thus, magnetic polarization58is referred to hereinafter as a baseline magnetic state58of flux concentrator56. Flux concentrator56is used to generally represent flux concentrator32and flux guides42. However, those skilled in the art will recognize that there are a wide variety of flux concentrator designs and functions. Hence, flux concentrator56is used herein to represent any ferromagnetic structure used in a magnetic field sensor to shield, concentrate, or guide a magnetic field.

For optimal response, flux concentrator56has a preferred magnetization orientation. That is, baseline magnetic state58for flux concentrator56will be directed in a uniform, i.e., generally single, direction. Unfortunately, ferromagnetic structures (e.g, flux concentrator56) are susceptible to corruption by exposure to externally applied magnetic fields (e.g., disturbing fields of thirty Gauss or higher). This magnetic corruption can alter the magnetic state of flux concentrator56leading to unstable device characteristics including offset, axis alignment, and noise.

FIG. 5shows a side view of flux concentrator56exemplifying a magnetic polarization61(represented by leftwardly directed arrows) having an altered orientation. Thus magnetic polarization61is referred to hereinafter as an altered magnetic state61.FIG. 5is provided to show the altered magnetic state of flux concentrator56in response to exposure to an externally applied magnetic field of sufficient strength (referred to herein as a magnetic shock event). As shown, altered magnetic state61may be directed in a uniform, i.e., generally single, direction that is opposite to the preferred magnetization orientation for flux concentrator56, e.g., baseline magnetic state58. The change in magnetization from baseline magnetic state58(FIG. 4) to altered magnetic state61can lead to offset shifts in the output signal, known as perming,

FIG. 6shows a side view of flux concentrator56exemplifying a magnetic polarization60having an unstable orientation. Again,FIG. 6is provided to show another type of altered magnetic state of flux concentrator56in response to exposure to an externally applied magnetic field of sufficient strength that results in a split polarization condition. Thus, magnetic polarization60is also referred to hereinafter as an altered magnetic state60of flux concentrator56. In this example, exposure to a magnetic shock event can reorient baseline magnetic state58(FIG. 4) of flux concentrator56so that upon returning to its low field sensing configuration, magnetic domain walls62(one shown) may be present in flux concentrator56. As exemplified inFIG. 5, magnetic domain walls62are regions in flux concentrator56at which the magnetic polarization points in different directions, resulting in altered magnetic state60.

The presence of one or more magnetic domain walls62results in non-uniformity in altered magnetic state60. Furthermore, domain walls62may travel up and down the length of flux concentrator56, thereby modulating the local field at the magnetic sense elements. The change in magnetization from baseline magnetic state58(FIG. 4) to altered magnetic state60can also lead to detrimental changes in magnetic sensor performance which can lead to elevated noise levels in the output signal63, offset shifts, and virtual rotation of sensor axis alignment. Exemplary embodiments described below recondition a ferromagnetic structure (e.g., flux concentrator56) by resetting its magnetic orientation from either of altered magnetic states61(as exemplified inFIG. 5) or60(as exemplified inFIG. 6) to baseline magnetic state58(as exemplified inFIG. 4) after being corrupted by an external disturbing field (e.g., a magnetic shock event).

FIG. 7shows a block diagram of a sensor package64having a corruption detection and reset subsystem66in accordance with an embodiment. Sensor package64generally includes a magnetic field sensor68having one or more magnetic sense elements70(one depicted) and one or more ferromagnetic structures, e.g., flux concentrators72(one depicted). Magnetic field sensor68is adapted to sense an external magnetic field74, depicted by arrows, and flux concentrator72is configured for shielding, flux concentrating, or flux redirecting purposes in accordance with a particular design. Sensor package64produces an output signal76, labeled MAGOUT, indicative of external magnetic field74.

For simplicity of illustration, magnetic field sensor68is generally shown with a single magnetic sense element70and a single flux concentrator72, and is therefore adapted to sense external magnetic field74along a single axis and produce a single output signal76. It should be understood, however, that sensor package64may be adapted to sense an external magnetic field along more than one axis, such as sensor package20(FIG. 1). In such a configuration, sensor package64would include multiple magnetic field sensors (e.g., X-axis magnetic field sensor24, Y-axis magnetic field sensor26, and Z-axis magnetic field sensor28shown inFIG. 1) and multiple suitably configured flux concentrators, such as those represented inFIGS. 2 and 3. Furthermore, magnetic field sensor68may include any quantity of sense elements70and flux concentrators72in accordance with particular design parameters.

Subsystem66, incorporated in sensor package64, includes at least one detector element78,80,82configured to detect altered magnetic states61or60(exemplified inFIGS. 5 and 6) of flux concentrator72, a processor84configured to determine when a reset action is needed in response to altered magnetic state61or60, and a current carrying structure86positioned in proximity to flux concentrator72. Current carrying structure86is utilized to apply a reset magnetic field106to flux concentrator72to reset flux concentrator72from altered magnetic state61or60to baseline magnetic state58(FIG. 4). Accordingly, subsystem66monitors for an altered magnetic state of a ferromagnetic structure within a magnetic field sensor package, determines whether a reset action is needed in response to the monitored data, and applies a reset magnetic field to the ferromagnetic structure only when a reset is needed.

Detector element78of subsystem66includes a high field magnetic sense element. Thus, detector element78is referred to hereinafter as high field magnetic sense element78. High field magnetic sense element78exhibits a sensitivity to external magnetic field74that is less than the sensitivity of magnetic sense element70of package64. By way of example, magnetic sense element70may be configured to detect external magnetic field74at a magnitude that is, for example, significantly less than thirty Gauss. However, high field magnetic sense element78may be configured to detect external magnetic field74only when it exceeds a magnetic field threshold. This magnetic field threshold can correspond to an expected magnitude of a magnetic shock event of, for example, approximately thirty Gauss or more.

When external magnetic field74exceeds the predetermined magnetic field threshold, high field magnetic sense element78produces an output signal88, labeled MAGHFinFIG. 7. Output signal88is indicative of an external disturbing field (e.g., a magnetic shock event) that may have been sufficient to alter the magnetic state of flux concentrator72. Thus, the presence of output signal88provides “detection” of a possible or anticipated magnetic state of flux concentrator72. Output signal88is communicated to processor84. Processor84executes a reset action determination process90to determine whether a reset action is required in response to receipt of output signal88, as will be discussed in greater detail below.

In the in-plane sensing directions (e.g., X-axis36and Y-axis38depicted inFIG. 2), the sensitivity of high field magnetic sense element78may be effectively decreased in a tunnel magnetoresistance (TMR) configuration by increasing the magnetic bias of the free layer. The magnetic bias of the free layer can be increased by reducing the spacing from the permanent magnet. Alternatively, in the in-plane sensing directions, the sensitivity may be effectively decreased by increasing shielding of the ferromagnetic layers over high field magnetic sense element78. In an out-of-plane direction (e.g., Z-axis40depicted inFIG. 3), a TMR configuration of high field magnetic sense element78may use a flux concentrator or a Hall sensor to achieve a suitable sensitivity.

Detector element80of subsystem66is included in processor84, and is referred to hereinafter as noise detector80. Noise detector80may be software, hardware, or a combination of software and hardware adapted to receive one or more output signals92, labeled MAG, from magnetic sense element70and detect a noise component on one or more output signals92. Processor84, executing reset action determination process90, can determine whether a reset action is required when the noise component on output signal92exceeds a noise threshold, as will be discussed in greater detail below.

Detector element82of subsystem66includes a magnetic state sensor94and a reference sensor96, and is referred to hereinafter as a flux concentrator state sensor82. Magnetic state sensor94is a magnetic field sensor that is located in proximity to flux concentrator72. Magnetic state sensor94is configured to detect a magnetic state of flux concentrator72. Reference sensor96is also magnetic field sensor. However, reference sensor96is displaced away from flux concentrator72and therefore does not detect the magnetic state of flux concentrator72. Instead, reference sensor96detects an ambient magnetic field. As will be discussed in greater detail below, a state signal98, labeled MAGSTATE, is provided by state sensor system82. State signal98is indicative of a difference in magnetic polarization between magnetic state sensor94and reference sensor96. Thus, state signal98provides a direct indication of altered magnetic state61(FIG. 5) of flux concentrator72. State signal98is communicated to processor84. Processor84, executing reset action determination process90, can determine whether a reset action is required when state signal98exceeds a difference threshold or falls outside of a predetermined range, as will be discussed in greater detail below.

Thus, corruption detection and reset subsystem66incorporated in sensor package64includes detector elements that monitor the environmental (exposure) conditions, the magnetic sensor output itself, and the state of critical ferromagnetic structural components of the magnetic sensor. More particularly, high field magnetic sense element78may be implemented for direct detection of a high magnetic field disturbing event (e.g., a magnetic shock event) indicating that flux concentrator72may be subject to magnetic corruption. Noise detector80implemented at processor84directly monitors the magnetic sensor output for noise levels indicative of magnetic corruption of the ferromagnetic structure. And, magnetic state sensor94of state sensor system82closely coupled to a section of the ferromagnetic structure together with reference sensor96provide direct monitoring of the magnetic state of the ferromagnetic structure.

The embodiment ofFIG. 7includes three detector elements78,80,82for illustrative purposes. However, alternative embodiments may include a single mode of monitoring or any suitable combination of two modes of monitoring for magnetic corruption of flux concentrator72.

Processor84of subsystem66may be incorporated as part of an ASIC or microcontroller of magnetic field sensor package64. Processor84may perform some or all functions of sensor package64including, but not limited to, signal conditioning and data management, stabilization control, bridge/output multiplexing, self-test, electrostatic discharge (ESD) protection, and so forth to produce output signal76. Additionally, processor84is configured to execute reset action determination process90in order to accumulate and analyze the information from detector elements78,80,82with appropriate fusing of the input information. Processor84, executing reset action determination process90, is further configured to deduce whether a performance-altering magnetic shock event has occurred and to determine when to trigger a reset action to reset flux concentrator72from either of altered magnetic states61or60(exemplified inFIGS. 5 and 6) back to baseline magnetic state58(FIG. 4). Although a single ASIC/MCU84is shown, it should be understood that sensor package64may include multiple processors adapted to perform various functions, as well as to execute reset action determination process90.

When a determination is made at processor84that a reset action is needed, processor84communicates an internal reset trigger100to a power source102. Power source102may include a battery, a connection to power external to magnetic field sensor package64, and/or control circuitry for management and provision of the power. In response to internal reset trigger100, power source102is configured to apply a direct current (DC) electric reset current104, labeled IRESET, to current carrying structure86. Reset current104generates reset magnetic field106at current carrying structure86, and a vector component of reset magnetic field106is applied to flux concentrator72in order to reverse the magnetization orientation and/or eliminate any domain walls62or other defects in the magnetic state of flux concentrator72(as exemplified inFIGS. 5 and 6).

Reset current104is a non-pulsed or pulsed electric current configured to generate reset magnetic field106such that the vector component of reset magnetic field106is of sufficient magnitude and proper orientation to reset flux concentrator72from the altered magnetic state back to its baseline magnetic state58(FIG. 4). In some embodiments, the magnitude of reset magnetic field106may be approximately thirty Gauss. In other embodiments, the magnitude may be approximately one hundred Gauss. And in still other embodiments, the magnitude may be somewhere between approximately thirty and approximately one hundred Gauss. The magnitude may be less than thirty Gauss and more than one hundred Gauss in still other embodiments.

In an embodiment, current carrying structure86may be a continuous coil structure located in proximity to flux concentrator72. For example, current carrying structure86may be positioned within a distance of approximately five microns from flux concentrator72, although the distance may be larger or smaller as well. Additionally, current carrying structure86may have a variety of shapes, sizes, and numbers of coils in accordance with a particular design best suited for applying reset magnetic field106to flux concentrator72. It should be further observed that in some embodiments, power source102may optionally be triggered via an external reset trigger108to provide reset current104to current carrying structure86periodically on a fixed schedule or when a user manually initiates a reset.

ReferringFIGS. 7 and 8,FIG. 8shows a chart110exemplifying the direct detection of a magnetic shock event120that may result in, or otherwise cause, an altered magnetic state of flux concentrator72. High field magnetic sense element78of corruption detection and reset subsystem66is used for direct detection magnetic shock event120. The detection of magnetic shock event120indicates the probability of an altered magnetic state of flux concentrator. It should be recalled that high field magnetic sense element78is configured to exhibit a relatively low sensitivity so that it does not detect external magnetic field74unless the magnitude of external magnetic field74exceeds a predetermined threshold112.

As shown in chart110, high field magnetic sense element78typically senses approximately zero for external magnetic field74due to its low sensitivity to external magnetic field74. However, as further shown, at time “T1”114, high field magnetic sense element78produces output signal88. The magnitude of output signal88exceeds threshold112. Additionally, output signal88may exceed threshold112from time “T1”114to time “T2”116determined to be of a duration118sufficient to alter the magnetic state of flux concentrator72. This change in output signal88from zero to a magnitude that exceeds threshold112for duration118signifies a high field disturbing event, i.e., magnetic shock event120, that could result in altering the magnetic state of flux concentrator72from baseline magnetic state58(FIG. 4). In response to direct detection of magnetic shock event120, execution of reset action determination process90may result in the production of internal reset trigger100, the provision of reset current104to current carrying structure86, and the generation of reset magnetic field106to reset flux concentrator72back to baseline magnetic state58.

Referring toFIGS. 9 and 10in connection withFIG. 7,FIG. 9shows a chart122exemplifying a baseline noise component124imposed upon output signals92of one or more magnetic sense elements70of magnetic field sensor package64, andFIG. 10shows a chart126exemplifying the direct monitoring of output signals92from magnetic sense elements70for noise levels indicative of magnetic corruption of flux concentrator72.

As mentioned previously, noise detector80of processor84is adapted to receive one or more output signals92, labeled MAG, from magnetic sense element(s)70and detect a noise component on one or more output signals92. As generally shown in chart122, baseline noise component124on output signals92(X-axis, Y-axis, and Z-axis) is below a noise threshold128. However, as shown in chart126, a noise component130on output signal92for Z-axis magnetic field sensing exceeds noise threshold128. This noise component130exceeding noise threshold128is indicative of magnetic corruption of flux concentrator72from a magnetic shock event. In response to noise component130exceeding noise threshold128, execution of reset action determination process90may result in the production of internal reset trigger100, the provision of reset current104to current carrying structure86, and the generation of reset magnetic field106to reset flux concentrator72back to baseline magnetic state58(FIG. 4).

Referring toFIGS. 11 and 12in connection withFIG. 7,FIG. 11shows a simplified top view of the implementation of state sensor system82to directly monitor the magnetic state of flux concentrator72andFIG. 12shows a simplified cross-sectional side view of state sensor system82with flux concentrator72. In the illustration ofFIG. 11, magnetic state sensor94underlies flux concentrator72. Hence, magnetic state sensor94is shown in dashed line view since it is obscured from sight inFIG. 11. As further shown in the illustration ofFIG. 11, reference sensor96is spatially displaced away from flux concentrator72.

FIGS. 11 and 12are illustrated to demonstrate an altered magnetic state of flux concentrator72in response to a disturbing event occurring within external magnetic field74relative to a baseline magnetic state. To that end, a first magnetic field path132, represented by dotted lines, represents altered magnetic state61(FIG. 5), and a second magnetic field path134, represented by dashed lines, represents baseline magnetic state58(FIG. 4). Both first and second magnetic field paths132,134are present inFIG. 11as basis for comparison and for simplicity of illustration. However, as discussed above in connection withFIGS. 4 and 5, flux concentrator72will either be in baseline magnetic state58or altered magnetic state61. Magnetic state sensor94is adapted to detect the magnetic state of flux concentrator72, e.g., exemplified by first and second magnetic field paths132,134, relative to reference sensor96following an external disturbing field (e.g., a magnetic shock event).

Referring now toFIGS. 13 and 14,FIG. 13shows a chart136exemplifying a spatial variation of the magnitude of the magnetic field on state sensors94,96of state sensor system82(FIG. 11), andFIG. 14shows a chart140exemplifying a temporal plot of the magnitude of the magnetic field before and after a perming event using state sensor system82, which includes magnetic state sensor94and reference sensor96(seeFIG. 11).

As shown in chart136, a first spatial plot line138demonstrates baseline magnetic state58, labeled BY-BASELINE, of flux concentrator72(corresponding to second magnetic field path134ofFIG. 11) as sensed at magnetic state sensor94. First spatial plot line138falls within an ambient magnetic field range144as sensed at reference sensor96, spaced a distance “X” away from flux concentrator72. That is, baseline magnetic state58, as represented by first spatial plot line138, represents the magnetic polarization of flux concentrator72when it has not been subjected to a disturbing magnetic field.

As further shown in chart136, a second spatial plot line142represents altered magnetic state61, labeled BY-PERMED, of flux concentrator72(corresponding to first magnetic field path132ofFIG. 11) as sensed at magnetic state sensor94. Second spatial plot line142also falls within ambient magnetic field range144, as sensed at reference sensor96, spaced distance “X” away from flux concentrator72. Thus second spatial plot line142is presented to demonstrate a perming event in which the magnetic polarization of flux concentrator72in altered magnetic state61may be opposite to the magnetic polarization of flux concentrator72in baseline magnetic state58.

Accordingly, the magnetic polarization of flux concentrator72in altered magnetic state61opposes the magnetic polarization of flux concentrator72in baseline magnetic state58, as detected at magnetic state sensor94. For example, the magnitude of the magnetic field in altered magnetic state61may be approximately equal but opposite in direction to the magnitude of the magnetic field in baseline magnetic state58. However, the magnetic field sensed at reference sensor96, regardless of whether flux concentrator72is in altered magnetic state61or in baseline magnetic state58will be generally equivalent. As such, a difference between the magnetic polarization sensed at magnetic state sensor94and sensed at reference state sensor96provides an indication of altered magnetic state61relative to baseline magnetic state58. This difference can be communicated to processor84(FIG. 7) as state signal98(FIG. 7).

As illustrated in the temporal plot ofFIG. 14, prior to a magnetic shock event146a magnitude of a magnetic field148sensed at magnetic state sensor94indicates that flux concentrator72is in baseline magnetic state58. However, following magnetic shock event146, magnitude of the magnetic field148sensed at magnetic state sensor94now indicates that flux concentrator72is in altered magnetic state61. In comparison, a magnitude of a magnetic field149measured at reference sensor96over the same time period remains within ambient magnetic field range144. Thus, chart140demonstrates a condition in which a perming effect (which can produce offset shifts in sensor output) has resulted in response to magnetic shock event146occurring at some point in time. In response to the detection of altered magnetic state61via state signal98(FIG. 7), execution of reset action determination process90may result in the production of internal reset trigger100, the provision of reset current104to current carrying structure86, and the generation of reset magnetic field106to reset flux concentrator72back to baseline magnetic state58(FIG. 4).

Referring toFIGS. 7 and 15,FIG. 15shows a flowchart of reset action determination process90executed within corruption detection and reset subsystem66in accordance with another embodiment. In general, flux concentrator reset process90is performed to detect an altered magnetic state of a ferromagnetic structure within a magnetic field sensor package, determine whether a reset action is needed in response to the monitored data, and apply a reset magnetic field to the ferromagnetic structure only when a reset is needed.

Process90is performed in a sensor package (e.g., sensor package64) that includes three detector elements, e.g., high field magnetic sense element78, noise detector80, and state sensor system82. The monitored data from the three detector elements78,80,82may be fused to determine whether a reset action is needed. In alternative embodiments, having more than or less than the three detector elements, a determination as to whether a reset action is needed can be made based on the combined received monitored data.

At a block150of process90, subsystem66monitors the magnetic state and/or anticipated magnetic state of flux concentrator72directly and/or indirectly. More particularly, data from the detector elements (e.g., high field magnetic sense element78, noise detector80, and state sensor system82) is received at processor84. In response to the receipt of monitored data, a query block152determines whether an altered magnetic state of flux concentrator72can be deduced. In the exemplary embodiment having three detector elements, an altered magnetic state of flux concentrator72may be detected in response to 1) receipt of output signal88from high field magnetic sense element78, and/or 2) receipt of output signal92from magnetic sense element70of magnetic field sensor package62, and/or 3) receipt of state signal98.

At query block152, when the monitored data falls within normal ranges, it can be deduced that flux concentrator72is in its baseline magnetic state58(FIG. 4). As such, process control loops back to block150to continue monitoring the magnetic state of flux concentrator72. However, when at least some of the monitored data falls outside of normal ranges, it can be deduced that flux concentrator72may be in either of altered magnetic states61and60(FIGS. 5 and 6). As such, process90proceeds to a query block154.

At query block154, processor84determines whether a reset action is needed in response to the altered magnetic state. That is, processor84can make an intelligent determination by fusing the monitored data from high field magnetic sense element78, from detector element80, and from state sensor system82. In an embodiment, processor84determines whether 1) output signal88detected at high field magnetic sense element78exceeds threshold112(FIG. 7), and/or 2) whether noise component130(FIG. 9) in output signal92from magnetic sense element70(as determined by detector element80) exceeds noise threshold128(FIG. 9), and/or 3) whether state signal98, representing the difference in magnetic polarization between magnetic state sensor94and reference sensor96, exceeds a difference threshold.

When processor84determines that a reset action is not needed, process control loops back to block150to continue monitoring the magnetic state of flux concentrator72. However, when processor84determines that a reset action is needed in response to the monitored data, process90continues at a block156. At block156, processor84produces internal reset trigger100. Internal reset trigger102is communicated to power source102and power source100communicates reset current104to current carrying structure86.

At a block158, reset magnetic field106is applied to flux concentrator72in response to receipt of reset current104at current carrying structure86. That is, reset current104generates reset magnetic field106about the conductive segments of current carrying structure86. A vector component of reset magnetic field106of sufficient magnetic flux density magnitude and proper orientation is applied to flux concentrator72via current carrying structure86in order to reset a magnetic polarization of flux concentrator72from altered magnetic state60back to its baseline magnetic state58(FIG. 4). The vector component of reset magnetic field106should meet or exceed a minimum threshold level of magnetic flux density sufficient to reset, i.e., “clean,” the magnetic polarization of flux concentrator72to produce the stable, baseline magnetic state58(FIG. 4).

After flux concentrator72is reset to the magnetic state from altered magnetic state61(FIG. 5) and/or to purge domain walls62(FIG. 6) so as to return to baseline magnetic state58(FIG. 4), power source102may discontinue the provision of reset current104, and magnetic sense element70with flux concentrator72within sensor package64may be utilized to sense external magnetic field74. Thereafter, process control loops back to block150to continue monitoring the magnetic state and/or the anticipated magnetic state of flux concentrator72.

FIG. 16shows a block diagram of a sensor package160in accordance with another embodiment. Sensor package160includes many of the components also included in sensor package64(FIG. 7). These components include magnetic sense element70, flux concentrator72, high field magnetic sense element78, detector element80, state sensor system82, processor84, current carrying structure86, and power source102. Details of the components and their function that are common to the components described above in connection with sensor package64will not be repeated herein.

A primary differentiation of sensor package160relative to sensor package64is that sensor package160includes a separate, second flux concentrator162that functions as a proxy for flux concentrator72. Accordingly, state sensor system82monitors a magnetic state of second flux concentrator162. An altered magnetic state of second flux concentrator162is indicative of the altered magnetic state of flux concentrator72. Therefore, determination of an altered magnetic state of second flux concentrator162may be used to determine whether flux concentrator72and second flux concentrator162are to be reset.

It is to be understood that certain ones of the process blocks depicted inFIG. 15may be performed in parallel with each other or with performing other processes. Furthermore, it is to be understood that the particular ordering of the process blocks depicted inFIG. 15may be modified, while achieving substantially the same result. Accordingly, such modifications are intended to be included within the scope of the inventive subject matter. In addition, although particular system configurations are described in conjunction withFIGS. 7 and 16, above, embodiments may be implemented in systems having other architectures, as well. These and other variations are intended to be included within the scope of the inventive subject matter.

Thus, various embodiments of a sensor package having a corruption detection and reset subsystem and methodology for detecting corruption of the magnetic state of a ferromagnetic structure and resetting the ferromagnetic structure to a baseline magnetic state have been described. An embodiment of a method in a sensor package having a ferromagnetic structure, the ferromagnetic structure being characterized by a baseline magnetic state, wherein the method comprises detecting an altered magnetic state of the ferromagnetic structure, the altered magnetic state differing from the baseline magnetic state. The method further comprises determining, at a processor within the sensor package, when a reset action is needed in response to the altered magnetic state and applying a reset magnetic field to the ferromagnetic structure via a current carrying structure positioned in proximity to the ferromagnetic structure to reset the ferromagnetic structure to the baseline magnetic state.

An embodiment of a sensor package comprises a magnetic field sensor, the magnetic field sensor including a magnetic sense element and a ferromagnetic structure proximate the magnetic sense element, the ferromagnetic structure being characterized by a baseline magnetic state. The sensor package further comprises a subsystem incorporated in the sensor package. The subsystem comprises a detector element configured to detect an altered magnetic state of the ferromagnetic structure, the altered magnetic state differing from the baseline magnetic state, a processor configured to determine when a reset action is needed in response to the altered magnetic state, and a current carrying structure positioned in proximity to the ferromagnetic structure, the current carrying structure being utilized to apply a reset magnetic field to the ferromagnetic structure to reset the ferromagnetic structure to the baseline magnetic state.

The methodology and sensor package, discussed above, and the inventive principles thereof enable the detection of corruption of the magnetic state of a ferromagnetic structure in a magnetic field sensor package and resetting the ferromagnetic structure to a baseline magnetic state. A corruption detection and reset subsystem within the sensor package ensures that the magnetic field sensor is “smart” in that it detects or otherwise anticipates a corrupting magnetic shock event directly and/or detects the effects of the magnetic shock event on the magnetization state of the ferromagnetic structures and/or detects the effects of the magnetic shock event on the output of the magnetic field sensor. The monitored data is analyzed within the subsystem to determine if and went to initiate a reset action. Accordingly, a reset action is applied when a reset is needed, as opposed to triggering periodically on a set schedule or tied to an external event, thereby achieving savings in power consumption.