Patent Publication Number: US-10330745-B2

Title: Magnetic field sensor with improved response immunity

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 15/061,190 filed Mar. 4, 2016 and entitled “MAGNETIC FIELD SENSOR WITH IMPROVED RESPONSE IMMUNITY,” which is incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     FIELD 
     This disclosure relates generally to magnetic field sensors, and more particularly, to a magnetic field sensor having an improved response immunity. 
     BACKGROUND 
     As is known, sensors of various types are used in a variety of applications. Sensors including one or more sensing elements (e.g., pressure sensing elements, temperature sensing elements, light sensing elements, acoustic sensing elements, and magnetic field sensing elements) are used to detect one or more parameters (e.g., pressure, temperature, light, sound, magnetic field). Magnetic field sensors, for example, are circuits including one or more magnetic field sensing elements, generally in combination with other circuit components (e.g., analog, digital and/or mixed signal components), and are used to detect a magnetic field. 
     In motion (e.g., rotation) detectors, for example, a magnetic field sensor may be used to detect motion of an object, such as a ferromagnetic object, for example, a gear or ring magnet. A magnetic field associated with the object is typically detected by one or more magnetic field sensing elements, such as Hall effect elements and/or magnetoresistance elements, which provide a signal (i.e., a magnetic field signal) proportional to an applied magnetic field. 
     Magnetic field sensing elements are typically sensitive to magnetic field strength and temperature. A magnetic field sensing element&#39;s response to an applied magnetic field (e.g., a magnetic field as may be affected by motion of a ferromagnetic object) may, for example, be a function of various factors including design parameters, such as materials, layer thickness and other dimensions, etc. Manufacturing tolerances and/or defects or irregularities (e.g., layer thickness or layer quality defects) formed during manufacture and/or use of magnetic field sensing elements may adversely affect a magnetic field sensing element&#39;s expected response (e.g., change in resistance) to an applied magnetic field and, thus, adversely affect the reliability of a resulting device (e.g., motion detector) in which the magnetic field sensing elements are provided. 
     In high precision sensing applications such as automobiles, accuracy in magnetic field sensing, such as may be used to detect motion of a target object, can be critical. Engine ignition timing, for example, depends on consistent detection accuracy. When magnetic field sensing elements of a magnetic field sensor integrated circuit (IC) in an engine ignition timing system respond to a magnetic field in an unknown and/or undesirable manner, detection accuracy by the magnetic field sensor IC, and the resulting accuracy or performance of the engine ignition timing system, can be negatively impacted (e.g., due to sudden unexpected changes in an output of magnetic field sensing elements). 
     SUMMARY 
     Described herein are concepts, systems, circuits and techniques related to a magnetic field sensor and a method for providing such a sensor with an improved response to an applied magnetic field and therefore improved sensing. More particularly, the resulting response can exhibit immunity to certain response deviations. 
     In one aspect of the concepts described herein, a magnetic field sensor includes a plurality of magnetoresistance elements, each having a respective length and width selected to provide a respective, different response to an applied magnetic field, wherein each of the plurality of magnetoresistance elements is coupled in parallel. With this arrangement, a condition causing an unexpected or undesirable response in one of the plurality of magnetoresistance elements will have a reduced impact on the magnetic field sensor accuracy. 
     The magnetic field sensor may include one or more of the following features individually or in combination with other features. A width of a first one of the plurality of magnetoresistance elements is different than and a multiple of a width of a second one of the plurality of magnetoresistance elements, and wherein a length of the first one of the plurality of magnetoresistance elements is the same as a length of the second one of the plurality of magnetoresistance elements. The respective, different responses of the plurality of magnetoresistance elements to the applied magnetic field may differ in linearity. Each of the plurality of magnetoresistance elements may have a substantially similar resistance when the applied magnetic field has a magnetic field strength of about zero Gauss. At least one of the plurality of magnetoresistance elements may experience a non-linear response to the applied magnetic field. At least two of the plurality of magnetoresistance elements may experience a non-linear response to the applied magnetic field. The non-linear response may be a result of a magnetic domain. The non-linear response experienced may also be a result of the applied magnetic field having a strength greater than a predetermined level. 
     The width of the first one of the plurality of magnetoresistance elements may also be approximately one-half the width of a second one of the plurality of magnetoresistance elements. 
     Each of the plurality of magnetoresistance elements may have a respective construction and the respective construction may comprise the at least one characteristic selected to provide the respective, different responses to the applied magnetic field. The respective construction may include one or more of: a material of one or more layers of the magnetoresistance element, a thickness of one or more layers of the magnetoresistance element, an ordering of one or more layers of the magnetoresistance element, and a spatial relationship of the magnetoresistance element with respect to the applied magnetic field. The plurality of magnetoresistance elements may be coupled in a bridge configuration. 
     The magnetic field sensor may include processing circuitry responsive to a magnetic field signal generated by the plurality of magnetoresistance elements in response to the applied magnetic field and configured to provide an output signal of the magnetic field sensor indicative of the applied magnetic field. The output signal of the magnetic field sensor may be indicative of one or more of a strength of the applied magnetic field, an angle of the applied magnetic field, a current associated with the applied magnetic field, and a speed and/or direction of movement of a ferromagnetic element that affects the applied magnetic field. 
     The magnetic field sensor may include processing circuitry responsive to a plurality of magnetic field signals, each generated by a respective one or more of the plurality of magnetoresistance elements in response to the applied magnetic field and configured to provide an output signal of the magnetic field sensor indicative of the applied magnetic field. The output signal of the magnetic field sensor may be indicative of one or more of a strength of the applied magnetic field, an angle of a direction of the applied magnetic field, a current associated with the applied magnetic field, and a movement of a ferromagnetic element that affects the applied magnetic field. The magnetic field sensor may be a current sensor. 
     The plurality of magnetoresistance elements may include one or more of a giant magnetoresistance (GMR) element, a magnetic tunnel junction (MTJ) element and a tunneling magnetoresistance (TMR) element. The plurality of magnetoresistance elements may include an anisotropic magnetoresistance (AMR) element. The magnetic field sensor may include a plurality of current sources, each coupled to one or more of the plurality of magnetoresistance elements. The magnetic field sensor can further include a controller configured to sample an output of each magnetoresistance element and provide an output signal as long as the outputs of each of the magnetoresistance elements respond in a similar manner to the applied magnetic field. 
     In another aspect of the concepts described herein, a method includes providing each of a plurality of magnetoresistance elements with at least one characteristic selected to provide a respective, different response to an applied magnetic field, wherein each of the plurality of magnetoresistance elements is coupled in parallel. 
     The method may include one or more of the following features either individually or in combination with other features. A width of a first one of the plurality of magnetoresistance elements is different than and a multiple of a width of a second one of the plurality of magnetoresistance elements, and wherein a length of the first one of the plurality of magnetoresistance elements is the same as a length of the second one of the plurality of magnetoresistance elements. Providing each of a plurality of magnetoresistance elements may include providing the each of the plurality of magnetoresistance elements with a response to the applied magnetic field that differs in linearity. Providing each of a plurality of magnetoresistance elements may include providing at least one magnetoresistance element that experiences a non-linear response to the applied magnetic field. Providing each of a plurality of magnetoresistance elements may include providing at least two magnetoresistance elements that experience a non-linear response to the applied magnetic field. 
     Providing each of a plurality of magnetoresistance elements may include coupling the plurality of magnetoresistance elements in a bridge configuration. The method may include providing a plurality of current sources, each coupled to one or more of the plurality of magnetoresistance elements. The method may include sampling an output of each magnetoresistance element and providing an output signal as long as the outputs of each of the magnetoresistance elements respond in a similar manner to the applied magnetic field. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing features of the disclosure, as well as the disclosure itself may be more fully understood from the following detailed description of the drawings, in which: 
         FIG. 1  is a block diagram of an example magnetic field sensor comprising a plurality of magnetoresistance elements according to the disclosure; 
         FIG. 2  shows a first example configuration of a sensing circuit that may form a portion of the magnetic field sensor of  FIG. 1 ; 
         FIG. 2A  shows a second example configuration of a sensing circuit that may form a portion of the magnetic field sensor of  FIG. 1 ; 
         FIG. 2B  shows a third example configuration of a sensing circuit that may form a portion of the magnetic field sensor of  FIG. 1 ; 
         FIG. 3  shows an illustrative characteristic curve associated with a single magnetoresistance element and an illustrative characteristic curve associated with an example configuration comprising a plurality of magnetoresistance elements according to the disclosure; 
         FIG. 4  shows an example configuration of magnetoresistance elements as may be provided in the magnetic field sensor of  FIG. 1 ; 
         FIG. 4A  is a block diagram of an example integrated circuit for detecting motion of an object, the integrated circuit including the monitor circuit of  FIG. 2 ; and 
         FIG. 5  is a block diagram of another example magnetic field sensor comprising a plurality of magnetoresistance elements according to a further aspect of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The features and other details of the concepts, systems, and techniques sought to be protected herein will now be more particularly described. It will be understood that any specific embodiments described herein are shown by way of illustration and not as limitations of the disclosure and the concepts described herein. Features of the subject matter described herein can be employed in various embodiments without departing from the scope of the concepts sought to be protected. Embodiments of the present disclosure and associated advantages may be best understood by referring to the drawings, where like numerals are used for like and corresponding parts throughout the various views. It should, of course, be appreciated that elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. 
     For convenience, certain introductory concepts and terms used in the specification are collected here. 
     As used herein, the term “magnetic field domain” is used to describe a region within a magnetic field sensing element in which magnetization of the magnetic material is in a uniform direction. In other words, individual magnetic moments of atoms within the magnetic material are aligned with each other in the region with the magnetic material and point in a same direction within the magnetic material. When a magnetic domain is aggravated and individual magnetic moments of atoms within a magnetic material are no longer aligned and pointing in a same direction (e.g., due to the magnetic material being subjected to a magnetic field having a having a strength greater than a predetermined level), the magnetic domain can cause the magnetic material and, thus, a magnetic field sensing element including the magnetic material, to have a non-linear response (e.g., experience a sudden jump in resistance) to an applied magnetic field. 
     As used herein, the term “magnetic field sensor” is used to describe a circuit that uses one or more magnetic field sensing elements, generally in combination with other components and/or circuits. Magnetic field sensors are used in a variety of applications, including, but not limited to, an angle sensor that senses an angle of a magnetic field, a current sensor that senses a magnetic field generated by a current carried by a current-carrying conductor, a magnetic switch that senses the proximity of a ferromagnetic object, a rotation detector that senses passing ferromagnetic articles, for example, magnetic domains of a ring magnet or features of a ferromagnetic target (e.g., gear teeth) where the magnetic field sensor is used in combination with a back-biased or other magnet, and a so-called linear magnetic field sensor that senses a magnetic field density of a magnetic field. 
     As used herein, the term “magnetic field sensing element” is used to describe a variety of electronic elements that can sense a magnetic field. The magnetic field sensing element can be, but is not limited to, a magnetoresistance element, a Hall effect element, or a magnetotransistor. As is known, there are different types of magnetoresistance (MR) elements, for example, a semiconductor magnetoresistance element such as Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, for example, a spin valve, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, and a magnetic tunnel junction (MTJ). As is also known, there are different types of Hall effect elements, for example, a planar Hall element, a vertical Hall element, and a Circular Vertical Hall (CVH) element. The magnetic field sensing element may be a single element or, alternatively, may include two or more magnetic field sensing elements arranged in various configurations, e.g., a half bridge or full (Wheatstone) bridge. Depending on the device type and other application requirements, the magnetic field sensing element may be a device made of a type IV semiconductor material such as Silicon (Si) or Germanium (Ge), or a type III-V semiconductor material like Gallium-Arsenide (GaAs) or an Indium compound, e.g., Indium-Antimonide (InSb). 
     As used herein, the term “processor” is used to describe an electronic circuit that performs a function, an operation, or a sequence of operations. The function, operation, or sequence of operations can be hard coded into the electronic circuit or soft coded by way of instructions held in a memory device. A “processor” can perform the function, operation, or sequence of operations using digital values or using analog signals. 
     In some embodiments, the “processor” can be embodied, for example, in a specially programmed microprocessor, a digital signal processor (DSP), or an application specific integrated circuit (ASIC), which can be an analog ASIC or a digital ASIC. Additionally, in some embodiments the “processor” can be embodied in configurable hardware such as field programmable gate arrays (FPGAs) or programmable logic arrays (PLAs). In some embodiments, the “processor” can also be embodied in a microprocessor with associated program memory. Furthermore, in some embodiments the “processor” can be embodied in a discrete electronic circuit, which can be an analog circuit, a digital circuit or a combination of an analog circuit and a digital circuit. The “controller” described herein may be provided as a “processor.” 
     As used herein, the term “motion” is used to describe a variety of types of movement associated with an object, for example, including rotational movement (or “rotation”) and linear (or “rectilinear”) movement of the object. A “motion detector” may, for example, detect rotation of an object. A “rotation detector” is a particular type of “motion detector.” 
     Additionally, while parallel magnetoresistance elements including a certain number of magnetoresistance elements (e.g., two or three) coupled in parallel are described in several examples below, it should be appreciated that the concepts, systems, circuits and techniques disclosed herein may be implemented using more than or less than the certain number of magnetoresistance elements coupled in parallel. 
     Further, it should be appreciated that, as used herein, relational terms, such as “first,” “second,” “top,” “bottom,” “left,” “right,” and the like, may be used to distinguish one element or portion(s) of an element from another element or portion(s) of the element without necessarily requiring or implying any physical or logical relationship or order between such elements. 
     Referring now to  FIG. 1 , an example magnetic field sensor system  100  includes a magnetic field sensor  130  having a plurality of magnetic field sensing elements  140  coupled in parallel and configured to provide an output signal  170   a  in response to an applied magnetic field (e.g., a magnetic field as may be generated by an object  120 , as will be discussed). 
     The magnetic field sensor  130 , which may be provided in the form of an integrated circuit (IC) in some embodiments, includes a signal path, or channel  150  (e.g., an analog, digital or mixed signal path). The sensor  130  also includes a memory device  160  (e.g., EEPROM or flash memory), and a controller  170 . The signal path  150  has an input coupled to an output of the parallel magnetic field sensing elements  140 , and an output coupled to the controller  170 . 
     The parallel magnetic field sensing elements  140  may be driven by one or more current and/or voltage sources (not shown) and include a plurality of magnetoresistance (MR) elements (e.g., GMR elements) coupled in parallel to form a parallel MR resistance. The parallel magnetic field sensing elements  140  may also include at least one other type of magnetic field sensing element (e.g., Hall effect element) in addition to the magnetoresistance elements in some embodiments. The other type of magnetic field sensing element may be coupled in series or in parallel with the with parallel magnetoresistance elements  140 . Further, the specific type of other magnetic field sensing element (e.g., vertical Hall effect element) may be selected such that the other magnetic field sensing element has a same or similar axis of sensitivity as parallel magnetoresistance elements  140 . 
     The applied magnetic field may be generated in various ways depending on the type of sensor system  100  and its application. For example, the applied magnetic field may be generated in response to motion of an object  120  (e.g., a ring magnet or ferromagnetic gear) having features, e.g., magnetic domains or gear teeth  120   a ,  120   b ,  120   c ,  120   d . For example, the object  120  can be disposed a shaft  110  (e.g., a steering shaft or a camshaft) configured to rotate in a direction  112 . The object  120  may also be coupled to an automobile wheel, as another example. The applied magnetic field may also be generated by a magnet (not shown) disposed proximate to or within the sensor  130 . With such a back-biased magnet configuration, motion of the object  120  can result in variations of the magnetic field sensed by the parallel magnetoresistance elements  140  and, thus, may result in variations of the magnetic field signal  140   a . It should be appreciated that the parallel magnetoresistance elements  140  may take any form and configuration suitable for detecting motion (e.g., speed of motion and/or direction of motion) of the object  120  by sensing a magnetic field affected by such motion. 
     Each of the parallel magnetoresistance elements  140  has at least one characteristic (e.g., length, width and/or construction, as will be discussed further below) selected to provide a respective, different response (e.g., change in resistance) to the applied magnetic field. The respective, different responses of the parallel magnetoresistance elements  140  to the applied magnetic field may, for example, differ in linearity, and correspond to at least one of the parallel magnetoresistance elements  140  experiencing a different, non-linear response to the applied magnetic field and/or a magnetic domain. In other words, each of the parallel magnetoresistance elements  140  may have a different susceptibility to response variations, such as may be due to the applied magnetic field and/or a magnetic domain. The foregoing may, for example, reduce the impact of magnetic domains associated with individual magnetoresistance elements of the parallel magnetoresistance elements  140 . As known, due to manufacturing constraints and tolerances magnetic domains and responses to a particular magnetic field strength can differ even amongst magnetoresistance elements intended to be identical. 
     In some embodiments, the parallel magnetoresistance elements  140  may include one or more of a giant magnetoresistance (GMR) element, a magnetic tunnel junction (MTJ) element and a tunneling magnetoresistance (TMR) element. Additionally, in some embodiments, the parallel magnetoresistance elements  140  may include an anisotropic magnetoresistance (AMR) element. In one embodiment, it is preferable for the parallel magnetoresistance elements  140  to be of a same or similar element type (e.g., GMR elements) with each of the parallel magnetoresistance elements  140  having the at least one characteristic selected to provide the respective, different response to the applied magnetic field. 
     The signal path  150 , which includes an amplifier  152 , a filter  154  and an analog-to-digital converter (ADC)  156  in the illustrated embodiment, is coupled to receive the magnetic field signal  140   a  at an input and configured to generate a signal (e.g., digital signal  156   a ) representative of the magnetic field signal  140   a  at an output. In particular, the amplifier  152  is coupled to receive the magnetic field signal  140   a  and configured to generate an amplified signal  152   a . Additionally, the filter  154  (e.g., a programmable analog filter) is coupled to receive the amplified signal  152   a  and configured to generate a filtered signal  154   a . Further, the ADC  156  is coupled to receive the filtered signal  154   a  and configured to generate a corresponding digital signal  156   a . The digital signal  156   a  is provided to a corresponding input of controller  170 . 
     The controller  170  (e.g., a synchronous digital controller or an analog controller), which may include diagnostic circuitry and/or software, for example, is coupled to receive at least the digital signal  156   a  at a respective input and configured to generate a controller output signal  170   a  at an output of the sensor  130 . The controller output signal  170   a  can be provided in a variety of signal formats, including, but not limited to, a SENT format, an I 2 C format, a PWM format, or a two-state binary format, and may be provided as a signal indicative of the magnetic field signal  140   a  (i.e., a signal indicative of the applied magnetic field). The controller output signal  170   a  may also be provided as a signal indicative of one or more of a strength of the applied magnetic field, a proximity of a target, an angle of the applied magnetic field, a current associated with the applied magnetic field, and a movement characteristic, such as speed and/or direction, of a ferromagnetic element (e.g., object  120 ) that affects the applied magnetic field. In some embodiments, the controller output signal  170   a  may be received by circuitry (e.g., analog, digital or mixed-signal circuitry) (not shown) for further processing (e.g., for generating filtered signals, amplified signals, and the like) and error reporting (e.g., to an engine control unit or ECU). For example, in the context of a magnetic field sensor that provides a speed indicating output signal  170   a , the controller  170  may include a peak detector that compares a digital version  156   a  of the magnetic field sensor signal  140   a  to a threshold signal. It will be appreciated that other processing circuitry can be provided in the controller  170  according to the desired information to be provided in the output signal  170   a.    
     While the sensor  130  may be provided in the form of an integrated circuit with an analog front end portion and a digital portion, it will be appreciated that the particular delineation of which circuit functions are implemented in an analog fashion or with digital circuitry and signals can be varied. For example, one or more portions of the signal path  150  (e.g., amplifier  152 , filter  154 , ADC  156 ) may be provided as part of the controller  170 . The controller  170  can, for example, perform the function, operation, or sequence of operations of one or more portions of the signal path  150 . Additionally, the memory device  160  can be provided as part of the controller  170  (e.g., as onboard EEPROM). Further, some of the illustrated circuit functions can be implemented on separate circuits (e.g., additional substrates within the same integrated circuit package, or additional integrated circuit packages, and/or on circuit boards). 
     Referring to  FIGS. 2-2B , example sensing circuits as may be provided in a magnetic field sensor, such as the sensor  130  of  FIG. 1  are shown. It should be appreciated that the example sensing circuits described below are but several of many potential configurations of sensing circuits in accordance with the concepts, systems, circuits and techniques described herein. 
     Referring to  FIG. 2 , an example sensing circuit  280  includes a plurality of magnetoresistance elements  242 ,  242 ′,  242 ″ (e.g., GMR elements), a signal path  250 , and a current source  232 . The magnetoresistance elements  242 ,  242 ′,  242 ″, which may be the same as or similar to the parallel magnetoresistance elements  140  of  FIG. 1 , are coupled in parallel and are referenced collectively by numeral  240 . The parallel magnetoresistance elements  240  have a first terminal coupled to the current source  232  and a second terminal coupled to a second terminal  202  of the sensing circuit  280 . Current source  232  (e.g., a constant or variable current source) is disposed in a signal path between a first terminal  201  of the sensing circuit  280  and the first terminal of the parallel magnetoresistance elements  240 . Additionally, the signal path  250  has an input coupled to a node N between the first and second terminals  201 ,  202  of the sensing circuit  280 , and an output coupled to an output of the sensing circuit  280 . The signal path  250  is shown with dotted lines to illustrate that in some embodiments, the signal path  250  can be external to the sensing circuit  280 . 
     The parallel magnetoresistance elements  240 , which may be used, for example, to provide an output signal of a magnetic field sensor (e.g.,  130 , shown in  FIG. 1 ) in response to an applied magnetic field (e.g., a magnetic field as may be generated by object  120  of  FIG. 1 ), are driven by the current source  232 . The current source  232  is coupled to a supply voltage, denoted as VCC at the first terminal  201  of the sensing circuit  280 , as may be received from a power supply (not shown), and is configured to drive the parallel magnetoresistance elements  240  with a corresponding current. 
     Each of the parallel magnetoresistance elements  240  has at least one characteristic (e.g., length, width and/or construction) selected to provide a respective, different response (e.g., change in resistance) to an applied magnetic field. The respective, different response of the parallel magnetoresistance elements  240  to the applied magnetic field may, for example, differ in linearity. In one embodiment, each of the parallel magnetoresistance elements  240  has a substantially similar resistance when the applied magnetic field has a magnetic field strength of about zero Gauss. Additionally, in one embodiment, at least one of the parallel magnetoresistance elements  240  experiences a non-linear response to the applied magnetic field. Further, in one embodiment, at least two of the parallel magnetoresistance elements  240  experience a non-linear response in response to the applied magnetic field. The non-linear response may, for example, be a result of a magnetic domain. In other words, each of the parallel magnetoresistance elements  240  may experience a respective, different response (e.g., have a different immunity) to the magnetic domain. The non-linear response may also be a result of the applied magnetic field having a strength greater than a predetermined level. In other words, each of the parallel magnetoresistance elements  240  may experience a respective, different response to the applied magnetic field having a strength greater than the predetermined level. The predetermined level may, for example, be based on type of the parallel magnetoresistance elements  240  (e.g., GMR or AMR elements). 
     Beyond having the at least one characteristic selected to provide the respective, different response to the applied magnetic field, the parallel magnetoresistance elements  240  may be the same as or similar to each other (e.g., in dimensions and/or construction) or may be different from each other. However, each of the parallel magnetoresistance elements  240  will have at least one characteristic selected to be different to provide the respective, different response to the applied magnetic field. 
     Changes in the applied magnetic field experienced by the parallel magnetoresistance elements  240  may cause the resistance (e.g., total resistance or parallel MR resistance) of the parallel magnetoresistance elements  240  to change. Additionally, in some embodiments, changes in temperature experienced by the parallel magnetoresistance elements  240  may also cause the resistance of the parallel magnetoresistance elements  240  to change. As the resistance of the parallel magnetoresistance elements  240  changes, a voltage at node N (i.e.,  242   a ) also changes. Additionally, as the resistance of the parallel magnetoresistance elements  240  changes, an output of the sensing circuit  280  (e.g., amplifier output signal  252   a ) and an output of a sensor (e.g.,  130 ) in which the sensing circuit  280  may be provided may also change. 
     Since magnetoresistance elements  242 ,  242 ′,  242 ″ are coupled in parallel in the example embodiment shown, the total resistance (i.e., R total ) or parallel MR resistance of the parallel magnetoresistance elements  240  is equal to R 242 ∥R 242′ ∥R 242″ , or 
                   R   242     ×     R     242   ′       ×     R     242   ″             (       R   242     ×     R     242   ′         )     +     (       R   242     ×     R     242   ″         )     +     (       R     242   ′       ×     R     242   ″         )         ,         
where R 242  corresponds to a resistance associated with magnetoresistance element  242 , R 242′  corresponds to a resistance associated with magnetoresistance element  242 ′, and R 242″  corresponds to a resistance associated with magnetoresistance element  242 ″. As one example result of this arrangement, in embodiments where one or more of the parallel magnetoresistance elements  240  (e.g., magnetoresistance element  242 ) experiences a non-linear response to the applied magnetic field (e.g., due to a magnetic domain or the applied magnetic field having a strength greater than a predetermined level), the total resistance of the parallel magnetoresistance elements  240  is minimally affected by the non-linear response of the one or more parallel magnetoresistance elements  240  to the applied magnetic field. It follows that the voltage at node N (i.e.,  242   a ), the output of the sensing circuit  280 , and the output of the sensor in which the sensing circuit  280  may be provided, likewise may be minimally affected by the non-linear response of the one or more parallel magnetoresistance elements  240  to the applied magnetic field. Detection accuracy of the sensing circuit  280  can thereby be improved over conventional arrangements.
 
     In other words, in contrast to conventional arrangements in which only a single magnetoresistance element is used, which single element may experience a non-linear response to an applied magnetic field, the parallel magnetoresistance elements  240  in the above-described arrangement may experience a reduced change in total resistance (e.g., a reduced impact from a magnetic domain) as a result of the parallel coupling of magnetoresistance elements  242 ,  242 ′,  242 ″ that have at least one characteristic (e.g., length, width and/or construction) selected to provide a respective, different response to the applied magnetic field. 
     For example, if magnetoresistance element  242  of the parallel magnetoresistance elements  240  in the above-described arrangement experiences a non-linear response to an applied magnetic field due to a magnetic domain, the total resistance of the parallel magnetoresistance elements  240  may be given by (R 242 +R domain )∥R 242′ ∥R 242″ , or 
                   (       R   242     +     R   domain       )     ×     R     242   ′       ×     R     242   ″                   (       (       R   242     +     R   domain       )     ×     R     242   ′         )     +                 (       (       R   242     +     R   domain       )     ×     R     242   ″         )     +     (       R     242   ′       ×     R     242   ″         )               ,         
where R domain  corresponds to the resistance change due to the magnetic domain. As illustrated, magnetoresistance elements  242 ′ and  242 ″ mask (or minimize) the impact of the magnetic domain on the total resistance of the parallel elements. In contrast, if only the magnetoresistance element  242  were used, the resulting resistance would be given by R 242 +R domain .
 
     The signal path  250 , which may be the same as or similar to signal path  150  described above in conjunction with  FIG. 1 , for example, is configured to provide an output signal (e.g., amplifier output signal  252   a ) of the sensing circuit  280 . The signal path  250  includes an amplifier  252  which may be the same as or similar to amplifier  152  of signal path  150  and may be powered by the supply voltage received at first terminal  201  of the sensing circuit  280  and coupled to receive a voltage  242   a  associated with magnetoresistance elements  240  at a first amplifier input (e.g., a non-inverting input). The amplifier  252  is also coupled to receive a reference signal (e.g., a ground or non-zero reference voltage) at a second amplifier input (e.g., an inverting input) and configured to generate an amplifier output signal  252   a  indicative of a voltage difference between the voltage  242   a  and the reference signal. The amplifier output signal  252   a  corresponds to an output signal of the sensing circuit  280  in the illustrated embodiment. 
     In some embodiments, the output of sensing circuit  280  (here, amplifier output signal  252   a ) may be received at an input of circuitry (e.g., controller  170 ) for further processing (e.g., to provide an output of a sensor IC). Additionally, in some embodiments, signal path  250  includes circuitry (e.g., proximity detector circuitry) to determine the speed, direction, proximity, angle, etc. of an object (e.g.,  120 , shown in  FIG. 1 ) based on changes in the applied magnetic field, and responses of the parallel magnetoresistance elements  240  to the applied magnetic field. 
     Referring to  FIG. 2A , a sensing circuit  1280  in accordance with another embodiment includes magnetoresistance elements  242 ,  242 ′ and signal path  250 . The sensing circuit  1280  also includes additional magnetoresistance elements  1242 ,  1242 ′,  2242 ,  2242 ′,  3242 ,  3242 ′ in the illustrated embodiment. Magnetoresistance elements  242 ,  242 ′,  1242 ,  1242 ′,  2242 ,  2242 ′,  3242 ,  3242 ′ are coupled in a bridge configuration (e.g., a Wheatstone bridge configuration), as denoted by reference numeral  1240 . The bridge configuration  1240  has a first terminal coupled to first terminal  201  of sensing circuit  1280  and a second terminal coupled to second terminal  202  of sensing circuit  1280 . 
     Each of the magnetoresistance elements of  FIG. 2A  is coupled in parallel with at least one other magnetoresistance element. In particular, magnetoresistance element  242 ′ is coupled in parallel with magnetoresistance element  242 , magnetoresistance element  1242 ′ is coupled in parallel with magnetoresistance element  1242 , magnetoresistance element  2242 ′ is coupled in parallel with magnetoresistance element  2242 , and magnetoresistance element  3242 ′ is coupled in parallel with magnetoresistance element  3242 . In some embodiments, more than two magnetoresistance elements may be coupled in parallel with each other, as shown in  FIG. 2 , for example. Each “arm” of the bridge configuration  1240  contains a same number of magnetoresistance elements (e.g., two) coupled in parallel, as shown in  FIG. 2A , for example. However, in other embodiments, it is possible for at least one “arm” of the bridge configuration  1240  to contain a different number of magnetoresistance elements coupled in parallel than other “arms” of the bridge configuration  1240 . 
     The parallel magnetoresistance elements of  FIG. 2A  each have at least one characteristic (e.g., length, width and/or construction) selected to provide a respective, different response (e.g., change in resistance) to an applied magnetic field in some embodiments. The foregoing may, for example, provide for each of the magnetoresistance elements of  FIG. 2A  having a different immunity to a magnetic domain, as discussed above in conjunction with  FIG. 2 . In other embodiments, each magnetoresistance element in a parallel-coupled pair or group of magnetoresistance elements (e.g.,  242 ,  242 ′) has at least one characteristic selected to provide a respective, different response to the applied magnetic field, but magnetoresistance elements in different parallel-coupled groups of magnetoresistance elements may have the same or similar response. For example, magnetoresistance elements  242 ,  1242 , which are not coupled in parallel in the illustrated embodiment, may have a same or similar response to the applied magnetic field in some embodiments. The foregoing may provide for each of the magnetoresistance elements of  FIG. 2A  (e.g.,  242 ,  242 ′,  1242 ) in a parallel-coupled pair or group of magnetoresistance elements having a different immunity to a magnetic domain. In one embodiment, it is preferable for each parallel-coupled pair or group of magnetoresistance elements to have a same or similar immunity response to the applied magnetic field (e.g., such that a probability of occurrence of a magnetic domain condition with one or more of the magnetoresistance elements is normalized). 
     Amplifier  252  of signal path  250  is coupled to receive a first output voltage  1242   a  generated at a first voltage node of the bridge configuration  1240  at a first amplifier input (e.g., non-inverting input), a second output voltage  1242   b  generated at a second voltage node of the bridge configuration  1240  at a second amplifier input (e.g., an inverting input), and configured to generate an amplifier output signal  1252   a  indicative of a voltage difference between the first output voltage  1242   a  and the second output voltage  1242   b . Amplifier output signal  1252   a  may correspond to an output signal of the sensing circuit  1280 . 
     As the resistance of the magnetoresistance elements in bridge configuration  1240  changes in response to an applied magnetic field as may be produced by motion of an object (e.g.,  120 , shown in  FIG. 1 ), for example, at least one of the first output voltage  1242   a  and the second output voltage  1242   b  may also change. The changes in the first output voltage  1242   a  and/or the second output voltage  1242   b  may be used to detect changes in the applied magnetic field. Since each of the magnetoresistance elements in at least a parallel-coupled pair or group of magnetoresistance elements has at least one characteristic selected to provide a respective, different response to the applied magnetic field, detection accuracy of the applied magnetic field may be minimally affected by an unexpected or undesirable (e.g., non-linear) response of one or more of the magnetoresistance elements to the applied magnetic field. 
     While the magnetoresistance elements of  FIG. 2A  (e.g.,  242 ,  242 ′,  1242 ) are shown coupled in a bridge configuration  1240  in the example embodiment shown, other arrangements are possible, for example, a resistor divider arrangement. Other possible arrangements include an arrangement in which the magnetoresistance elements are used as load resistors in an amplifier stage, a half-bridge circuit comprising the magnetoresistance elements, and a circuit including at least one parallel-coupled pair or group of magnetoresistance elements which are coupled to a current source. Many other arrangements are, of course, possible, as will be apparent to one of skill in the art. 
     Referring to  FIG. 2B , in which like elements of  FIGS. 2 and 2A  are provided having like reference designations, a sensing circuit  2280  in accordance with another embodiment includes magnetoresistance elements  242 ,  242 ′,  1242 ,  1242 ′,  2242 ,  2242 ′,  3242 ,  3242 ′ and signal path  250 . The sensing circuit  2280  also includes current sources  232 ,  232 ′,  1232 ,  1232 ′,  2232 ,  2232 ′,  3232 ,  3232 ′ in the illustrated embodiment. Current sources  232 ,  232 ′,  1232 ,  1232 ′,  2232 ,  2232 ′,  3232 ,  3232 ′, which may be the same as or similar to each other in some embodiments, are each coupled to one or more of the magnetoresistance elements  242 ,  242 ′,  1242 ,  1242 ′,  2242 ,  2242 ′,  3242 ,  3242 ′ and in a bridge configuration (e.g., a Wheatstone bridge configuration), as denoted by reference numeral  2240 . 
     The current sources of  FIG. 2B  are each coupled to receive the supply voltage, denoted as VCC, at the first terminal  201  of the sensing circuit  2280 , and are configured to drive the magnetoresistance elements with corresponding current signals. The magnitude of these current signals may, for example, be adjusted to bias one or more of the magnetoresistance elements to provide for improved accuracy in the sensing circuit  2280  (e.g., by providing temperature compensation in the sensing circuit  2280 ). As one example, temperature compensation may be provided in sensing circuit  2280  by adjusting the magnitude of the current signals to maintain a same or similar voltage level at one or more voltage nodes in the sensing circuit  2280  (e.g., a first voltage node, as will be discussed) regardless of temperature. Although the current sources of  FIG. 2B  (e.g.,  232 ) are each shown as coupled to a single magnetoresistance element (e.g.,  242 ) in the illustrated embodiment, it should be appreciated that in other embodiments one or more of the current sources of  FIG. 2B  may be coupled to two or more magnetoresistance elements. 
     Amplifier  252  of signal path  250  is coupled to receive a first output voltage  2242   a  generated at a first voltage node of the bridge configuration  2240  at a first amplifier input (e.g., non-inverting input), a second output voltage  2242   b  generated at a second voltage node of the bridge configuration  2240  at a second amplifier input (e.g., inverting input), and is configured to generate an amplifier output signal  2252   a  indicative of a voltage difference between the first output voltage and the second output voltage. Amplifier output signal  2252   a  corresponds to an output signal of the sensing circuit  2280  in the illustrated embodiment. 
     While the sensing circuits of  FIGS. 2-2B  are shown as including a certain number of magnetoresistance elements with the magnetoresistance elements positioned in a particular manner, it should be appreciated that other configurations of magnetoresistance elements are possible in accordance with the concepts, systems, circuits and techniques sought to be protected herein. The circuits may be implemented using more than or less than the number of magnetoresistance elements shown, and the magnetoresistance elements may be configured in other manners than that which is shown. 
     Referring to  FIG. 3 , illustrative characteristic curves as may be representative of response characteristics of magnetoresistance elements, which can be the same as or similar to the magnetoresistance elements described above in conjunction with  FIGS. 1-2B , for example, are shown in a plot  300 . The magnetoresistance elements can be provided, for example, in a magnetic field sensor which can be the same as or similar to magnetic field sensor  130  of  FIG. 1 . Plot  300  has a horizontal axis with a scale in degrees corresponding, for example, to rotation of an object (e.g., object  120 , shown in  FIG. 1 ) with respect to the magnetoresistance elements, and a vertical axis with a scale in ohms corresponding to resistance of the magnetoresistance elements. 
     Plot  300  includes a first characteristic curve  310  representative of a response characteristic of a single magnetoresistance element (e.g.,  242 ), and a second characteristic curve  320  representative of a combined response characteristic of a plurality of magnetoresistance elements (e.g.,  242 ,  242 ′,  242 ″) coupled in parallel (e.g.,  240 ), for example, as shown in  FIGS. 2-2B , when subjected to a magnetic field (e.g., an applied magnetic field). 
     Curve  310  is represented by a line with markings (e.g., circle markings) and overlaps curve  320 , which is represented by a line without markings, for a substantial portion of the plot  300 , as will be discussed below. Each of the parallel-coupled magnetoresistance elements characterized by curve  320  has at least one characteristic (e.g., length, width and/or construction) selected to provide a respective, different response to an applied magnetic field. The plurality of magnetoresistance elements characterized by curve  320  may include the magnetoresistance element characterized by curve  310 . 
     As illustrated, the resistance of the magnetoresistance element characterized by curve  310  and the resistance (e.g., total resistance) of the parallel magnetoresistance elements characterized by curve  320  generally change in response to changes in a magnetic field strength experienced by the magnetoresistance element(s), except for when the magnetoresistance element(s) is/are in a so-called saturation region in which the resistance of the magnetoresistance element(s) substantially levels off. 
     As is also illustrated, the curves  310  and  320  are substantially the same (and the magnetoresistance element(s) characterized by the curves  310  and  320  have substantially the same resistance) until the magnetoresistance element(s) experience a first magnetic field strength, for example, at a first rotation position of the object, as represented by point  302 . At point  302 , the magnetoresistance element characterized by curve  310  experiences a sudden increase in resistance, while the combined resistances of parallel-coupled magnetoresistance elements characterized by curve  320  continue to decrease. In the example embodiment shown, the magnetoresistance element characterized by curve  310  experiences an increase in resistance from the first magnetic field strength at point  302  until a second, different magnetic field strength, for example, at a second rotation position of the object, as represented by point  303 . At point  303 , the magnetoresistance element characterized by curve  310  experiences a sudden decrease in resistance. Additionally, at point  304 , which corresponds to a third, different magnetic field strength, for example, experienced by the magnetoresistance element(s) at a third rotation position of the object, curves  310  and  320  meet again, with the magnetoresistance element(s) characterized by curves  310  and  320  having a substantially similar resistance at the third magnetic field strength. 
     The sudden resistance changes illustrated by curve  310  relative to curve  320  between points  302  and  304  may, for example, correspond to the magnetoresistance element characterized by curve  310  experiencing a substantial non-linear response to the applied magnetic field (e.g., due to a magnetic domain or the applied magnetic field having a strength greater than a predetermined level), while the combined resistance of the parallel-coupled magnetoresistance elements characterized by curve  320 , which may include the magnetoresistance element characterized by curve  310 , is substantially immune to the adverse response characteristic of one of its constituent parallel-coupled elements. For example, parallel magnetoresistance elements characterized by curve  320  may experience a slightly non-linear response or may even remain substantially linear due to the parallel coupling of its magnetoresistance elements. The foregoing may provide for improved detection accuracy by the parallel magnetoresistance elements and, more importantly, detection accuracy of a magnetic field sensor in which the parallel magnetoresistance elements may be provided. 
     Referring to  FIG. 4 , an example plurality of magnetoresistance elements  442 ,  442 ′,  442 ″ as may be coupled in parallel and provided in a magnetic field sensor ( FIG. 1 ) is shown. Magnetoresistance elements  442 ,  442 ′,  442 ″ (e.g., GMR yokes or yoke structures), which may be the same as or similar to magnetoresistance elements  242 ,  242 ′,  242 ″ of  FIG. 2 , are coupled in parallel and supported by a substrate (not shown). The substrate may be a semiconductor substrate or any other material substrate that can support electrical components and may be provided in the form of an integrated circuit. It is also possible that the parallel-coupled magnetoresistance elements may be provided on separate electrically coupled substrates within the same integrated circuit package. Similar to the magnetoresistance elements described above, each of the magnetoresistance elements has at least one characteristic (e.g., dimensions and/or construction) selected to provide a respective, different response to an applied magnetic field. 
     In the example embodiment shown, each of the magnetoresistance elements  442 ,  442 ′,  442 ″ has a respective length and width. Additionally, each of the magnetoresistance elements  442 ,  442 ′,  442 ″ has a first major surface (e.g.,  443 ,  443 ′,  443 ″) and a second opposing major surface (not shown). The second major surface may be parallel, or parallel within manufacturing tolerances, to the respective first major surface. A first dimension across first major surface  443  (e.g., a major axis of the first major surface  443 ) of a first one of the magnetoresistance elements  442  may correspond to a length of the first magnetoresistance element  442  and a second dimension across the first major surface  443  (e.g., a minor axis of the first major surface  443 ) may correspond to a width of the first magnetoresistance element  442 . Additionally, a first dimension across a first major surface  443 ′ of a second one of the magnetoresistance elements  442 ′ may correspond to a length of the second magnetoresistance element  442 ′ and a second dimension across the first major surface  443 ′ may correspond to a width of the second magnetoresistance element  442 ′. Further, a first dimension across a first major surface  443 ″ of a third one of the magnetoresistance elements  442 ″ may correspond to a length of the third magnetoresistance element  442 ″ and a second dimension across the first major surface  443 ″ may correspond to a width of the third magnetoresistance element  442 ″. 
     The above-described length and width dimensions of the magnetoresistance elements  442 ,  442 ′,  442 ″ may comprise the at least one characteristic selected to provide the respective, different responses (e.g., corresponding changes in resistance) to the applied magnetic field in some embodiments. As one example, the length and width of first magnetoresistance element  442  may be a multiple of the length and width of second magnetoresistance element  442 ′. Additionally, the length and width of second magnetoresistance element  442 ′ may be a multiple of the length and width of third magnetoresistance element  442 ″. For example, the length and width of first magnetoresistance element  442  may be approximately one-half the length and width of second magnetoresistance element  442 ′. Additionally, the length and width of second magnetoresistance element  442 ′ may be approximately one-half the length and width of third magnetoresistance element  442 ″. Other multiples (e.g., one-third, one-fourth, etc.) of the lengths and widths of the magnetoresistance elements  442 ,  442 ′,  442 ″ are possible. 
     In one embodiment, it is preferable for the magnetoresistance elements  442 ,  442 ′,  442 ″ to each have the characteristic (e.g., length and/or width) selected to be different in order to provide the respective, different response to the applied magnetic field, as in the above example in which each of the magnetoresistance elements  442 ,  442 ′,  442 ″ has a different length and width than the other magnetoresistance elements. In another embodiment, two of the magnetoresistance elements  442 ,  442 ′,  442 ″ may have a first characteristic (e.g., length and/or width) selected to be different while one of the magnetoresistance elements may have a second characteristic (e.g., construction) selected to be different. For example, magnetoresistance elements  442 ,  442 ′ may each have lengths and widths selected to be different than each other, while magnetoresistance element  442 ″ may have a same length and width as one of the magnetoresistance elements  442 ,  442 ′ but have a construction (e.g., layer stack up) selected to be different. 
     The respective lengths and widths of the magnetoresistance elements  442 ,  442 ′,  442 ″ may also be selected such that each magnetoresistance element  442 ,  442 ′,  442 ″ has at least one different dimension (e.g., length), while also retaining a substantially similar resistance when subjected to substantially no magnetic field (i.e., a magnetic field with a strength of about zero Gauss). For example, each of the magnetoresistance elements  442 ,  442 ′,  442 ″ may have a same or similar width but have a different length to provide for a substantially similar resistance when subjected to substantially no magnetic field. In this scenario, the length may comprise the at least one characteristic selected to provide the respective, different responses to the applied magnetic field. Alternatively, the width may comprise the at least one characteristic selected to provide the respective, different responses to the applied magnetic field while the lengths of the parallel-coupled elements may be substantially the same. As shown in  FIG. 4A , the width of elements  442 ,  442 ′″,  442 ″″ are each different while the lengths of elements  442 ,  442 ′″,  442 ″″ are substantially the same. Each of the magnetoresistance elements  442 ,  442 ′″,  442 ″″ has a first major surface (e.g.,  443 ,  443 ′″,  443 ″″) and a second opposing major surface (not shown). The second major surface may be parallel, or parallel within manufacturing tolerances, to the respective first major surface. 
     In general, the respective lengths and widths of the magnetoresistance elements  442 ,  442 ′,  442 ″ may be any lengths and widths that provide for a respective, different response to an applied magnetic field. Additionally, the lengths and widths of the magnetoresistance elements  442 ,  442 ′,  442 ″ can be made to have any dimensions within manufacturing capabilities to achieve any desired resistance, and provide for the respective, different response to the applied magnetic field. 
     In some embodiments, one or more parameters associated with the construction of each of the magnetoresistance elements  442 ,  442 ′,  442 ″ may comprise the at least one characteristic selected to provide the respective, different responses to the applied magnetic field. Illustrative construction parameters include one or more of: a material, a layer thickness, and a ordering of one or more layers (e.g., antiferromagnetic layers, pinned layers and/or non-magnetic layers) of the magnetoresistance elements  442 ,  442 ′,  442 ″. The respective construction may also include a spatial relationship of the magnetoresistance elements  442 ,  442 ′,  442 ″ on one plane, for example, relative to an applied magnetic field. For example, magnetoresistance elements  442 ,  442 ′,  442 ″ may each be supported by a semiconductor substrate with magnetoresistance element  442  positioned closer to an edge of the substrate than magnetoresistance element  442 ′ and magnetoresistance element  442 ′ positioned closer to the edge of the substrate than magnetoresistance element  442 ″. 
     As one example, magnetoresistance elements  442 ,  442 ′,  442 ″ may each comprise multiple layers (i.e., a material stack) including one or more antiferromagnetic layers, one or more pinned layers, and/or one or more non-magnetic layers. The antiferromagnetic layers may include Manganese-Platinum (MnPt), the pinned layers may include Cobalt-Iron (CoFe), and the non-magnetic layers may include a select one of Iridium (Ir) and Ruthenium (Ru) as a few examples. 
     In general, the material, layer thickness, and ordering of the layers (e.g., antiferromagnetic and non-magnetic layers) of the magnetoresistance elements  442 ,  442 ′,  442 ″ can affect the manner in which the magnetoresistance elements  442 ,  442 ′,  442 ″ respond to an applied magnetic field. 
     Referring to  FIG. 5 , in which like elements of  FIG. 1  are provided having like reference designations, a magnetic field sensor system  500  in accordance with another embodiment includes a magnetic field sensor  530 , as may be provided in the form of an integrated circuit (IC). The sensor  530  includes magnetic field sensing element(s)  540 , magnetic field sensing element(s)  1540  and magnetic field sensing element(s)  2540 , each of which includes at least one magnetoresistance element (e.g., a GMR element). The sensor  530  additionally includes respective signal paths, or channels  150 ,  1150  and  2150 . The signal path  150  has an input coupled to an output of magnetic field sensing element(s)  540  and an output coupled to a corresponding input of a controller  170 . Additionally, the signal path  1150  has an input coupled to an output of magnetic field sensing element(s)  1540  and an output coupled to a corresponding input of the controller  170 . Further, the signal path  2150  has an input coupled to an output of magnetic field sensing element(s)  2540  and an output coupled to a corresponding input of the controller  170 . 
     Magnetic field sensing element(s)  540 , which includes at least one magnetoresistance element (e.g., a GMR element), may be driven by a first current source (not shown) and configured to generate a magnetic field signal (e.g., magnetic field signal  540   a ) in response to an applied magnetic field (e.g., a magnetic field as may be generated by motion of object  120 ). 
     Magnetic field sensing element(s)  540  may also include at least one other type of magnetic field sensing element (e.g., Hall effect element) in addition to the at least one magnetoresistance element  540  in some embodiments. The other type of magnetic field sensing element, which may be sensitive in a same direction or plane as magnetic field sensing element(s)  540 , may also be configured to generate a magnetic field signal (e.g., magnetic field signal  540   a ) in response to the applied magnetic field. The applied magnetic field, as may be sensed by magnetic field sensing element(s)  540 , may be similar to the applied magnetic fields discussed in the figures above and generated in various ways depending on the type of sensor  530  and its application. As one example, the applied magnetic field may be generated in response to motion of the object  120 . 
     Signal path  150  is coupled to receive the magnetic field signal  540   a  at an input and configured to generate a signal (e.g., digital signal  156   a ) representative of the magnetic field signal  540   a  at an output. In particular, amplifier  152  of the signal path  150  is coupled to receive the magnetic field signal  540   a  and configured to generate an amplified signal  152   a . Additionally, filter  154  of the signal path  150  is coupled to receive the amplified signal  152   a  and configured to generate a filtered signal  154   a . Further, ADC  156  of the signal path  150  is coupled to receive the filtered signal  154   a  and configured to generate a corresponding digital signal  156   a . The digital signal  156   a  is provided to a corresponding input of controller  170 . 
     Magnetic field sensing element(s)  1540 ,  2540  may be the same as or similar to magnetic field sensing element(s)  540  with each including at least one magnetoresistance element. Each of magnetoresistance elements  540 ,  1540 ,  2540  has at least one characteristic selected to provide a respective, different response to the applied magnetic field. The at least one selected characteristic for each of elements  540 ,  1540 ,  2540  may be the same or different. Additionally, signal paths  1150 ,  2150  may be the same as or similar to signal path  150 , as shown. Signal path  1150  is coupled to receive a magnetic field signal  1540   a  at an input and configured to generate a signal (e.g., digital signal  1156   a ) representative of the magnetic field signal  1540   a  at an output. Additionally, signal path  2150  is coupled to receive a magnetic field signal  2540   a  at an input and configured to generate a signal (e.g., digital signal  2156   a ) representative of the magnetic field signal  2540   a  at an output. 
     The controller  170  (i.e., processing circuitry) is coupled to receive at least the digital signal  156   a , the digital signal  1156   a , and the digital signal  2156   a  at respective inputs and configured to generate a controller output signal  570   a  at an output of the sensor  530 . The controller output signal  570   a  may be provided as a signal indicative of at least one of the magnetic field signal  540   a , the magnetic field signal  1540   a , and the magnetic field signal  2540   a  (i.e., a signal indicative of the applied magnetic field). The controller output signal  570   a  may also be provided as a signal indicative of one or more of a strength of the applied magnetic field, a proximity of an object, an angle of the applied magnetic field, a current associated with the applied magnetic field, and a movement (e.g., speed and/or direction) of a ferromagnetic element (e.g., object  120 ) that affects the applied magnetic field. In some embodiments, the controller output signal  570   a  may be received by circuitry (e.g., analog, digital or mixed-signal circuitry) (not shown) for further processing (e.g., for generating filtered signals, amplified signals, and the like) and error reporting (e.g., to an engine control unit or ECU). 
     Additionally, in some embodiments, the controller  170  may be configured to evaluate or poll (i.e., sample) each of magnetic field sensing element(s)  540 ,  1540 ,  2540  (or outputs of each of magnetic field sensing element(s)  540 ,  1540 ,  2540 ) at predetermined time periods through use of one or more algorithms in the controller  170 . As one example, the controller  170  may evaluate the outputs of the magnetic field sensing element(s)  540 ,  1540 ,  2540  (i.e., may evaluate signals  156   a ,  1156   a ,  2156   a ) with one or more detectors (e.g., peak detectors). As long as at least two of the outputs of the magnetic field sensing element(s)  540 ,  1540 ,  2540  respond in a same or similar manner to the applied magnetic field (e.g., two detector outputs switch at substantially the same time), as may be determined through one or more logic operations (e.g., exclusive-or operation), for example, the controller  170  may provide an output signal (here, controller output signal  570   a ) indicative of a speed of motion of the object  120  or a direction of motion of the object  120 . In other words, as one result of each of the magnetic field sensing element(s)  540 ,  1540 ,  2540  having at least one characteristic selected to provide a respective, different response to the applied magnetic field, the output signal  570   a  of the controller  170  is not affected (or at least is less affected) if one of the magnetic field sensing element(s)  540 ,  1540 ,  2540  has an unexpected or undesirable response to the applied magnetic field (e.g., due to a magnetic domain or the applied magnetic field having a strength greater than a predetermined level). 
     As described above and will be appreciated by those of ordinary skill in the art, embodiments of the disclosure herein may be configured as a system, method, or combination thereof. Accordingly, embodiments of the present disclosure may be comprised of various means including hardware, software, firmware or any combination thereof. Furthermore, embodiments of the present disclosure may take the form of a computer program product on a computer-readable storage medium having computer readable program instructions (e.g., computer software) embodied in the storage medium. Any suitable non-transitory computer-readable storage medium may be utilized. 
     It is to be appreciated that the concepts, systems, circuits and techniques sought to be protected herein are not limited to use in a particular application but rather, may be useful in substantially any application where it is desired to detect a magnetic field. 
     Having described preferred embodiments, which serve to illustrate various concepts, structures and techniques, which are the subject of this patent, it will now become apparent to those of ordinary skill in the art that other embodiments incorporating these concepts, structures and techniques may be used. Additionally, elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. 
     Accordingly, it is submitted that that scope of the patent should not be limited to the described embodiments but rather should be limited only by the spirit and scope of the following claims.