Abstract:
Magnetic field sensor arrangements and methods provide a magnetic field sensor positioned proximate to a magnet with an axis of sensitivity aligned relative to the magnet in orientations that provide a good sensitivity and a mechanical difference from other arrangements.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       FIELD OF THE INVENTION 
       [0003]    This invention relates generally to magnetic field sensor arrangements and, more particularly, to a magnetic field sensor arrangement for which a magnetic field sensor is oriented relative to a magnet in a particular ways. 
       BACKGROUND OF THE INVENTION 
       [0004]    Planar Hall elements and vertical Hall elements are known types of magnetic field sensing elements that can be used in magnetic field sensors. A planar Hall element tends to be responsive to (i.e., have a major response axis aligned with) magnetic fields perpendicular to a surface of a substrate on which the planar Hall element is formed. A vertical Hall element tends to be responsive to (i.e., have a major response axis aligned with) magnetic fields parallel to a surface of a substrate on which the vertical Hall element is formed. 
         [0005]    Other types of magnetic field sensing elements are known. For example, a so-called “circular vertical Hall” (CVH) sensing element, which includes a plurality of vertical magnetic field sensing elements, is known and described in PCT Patent Application No. PCT/EP2008/056517, entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, and published in the English language as PCT Publication No. WO 2008/145662, which application and publication thereof are incorporated by reference herein in their entirety. The CVH sensing element is a circular arrangement of vertical Hall elements arranged over a common circular implant region in a substrate. The CVH sensing element can be used to sense a direction (and optionally a strength) of a magnetic field in a plane of the substrate. A CVH sensing elements tends to be responsive to (i.e., have a major response axis aligned with) magnetic fields parallel to a surface of the substrate on which the CVH sensing element is formed 
         [0006]    Various parameters characterize the performance of magnetic field sensing elements. These parameters include sensitivity, which is a change in an output signal of a magnetic field sensing element in response to a change of magnetic field experienced by the magnetic sensing element, and linearity, which is a degree to which the output signal of the magnetic field sensing element varies in direct proportion to the magnetic field. These parameters also include an offset, which is characterized by an output signal from the magnetic field sensing element not representative of a zero magnetic field when the magnetic field sensing element experiences a zero magnetic field. 
         [0007]    Another parameter that can characterize the performance of a CVH sensing element is the speed with which output signals from vertical Hall elements within the CVH sensing element can be sampled, and thus, the speed with which a direction of a magnetic field can be identified. Yet another parameter that can characterize the performance of a CVH sensing element is the resolution (e.g., angular step size) of the direction of the magnetic field that can be reported by the CVH sensing element. 
         [0008]    As described above, the CVH sensing element is operable, with associated circuits, to provide an output signal representative of an angle of a direction of a magnetic field. Therefore, as described below, if a magnet is disposed upon or otherwise coupled to a so-called “target object,” for example, a camshaft in an engine, the CVH sensing element can be used to provide an output signal representative of an angle of rotation, and/or a rotation speed, and/or a rotation direction, of the target object. 
         [0009]    Some conventional magnetic field sensor arrangements position a magnetic field sensor and associated magnetic field sensing element along an axis of rotation of a ring magnet configured to rotate, the ring magnet coupled to a target object. In these arrangements, the magnetic field sensor is disposed such that the major response axis of the magnetic field sensing element within the magnetic field sensor is perpendicular to the axis of rotation of the ring magnet and parallel to a major surface of the ring magnet. 
         [0010]    Other conventional magnetic field sensor arrangements position a magnetic field sensor and associated magnetic field sensing element proximate to a line magnet configured to move linearly, the line magnet coupled to a target object. 
         [0011]    However, due to mechanical constraints, the conventional orientations of a magnetic field sensor relative to a magnet may not be achievable in all installations of the magnetic field sensor. Furthermore, the conventional orientations may not achieve a closest distance between the magnetic field sensing element and the magnet, which is desirable for high sensitivity. Therefore it is desirable to provide a magnetic field sensor arrangement for which the magnetic field sensor is positioned such that a magnetic field sensing element therein has an axis of sensitivity not parallel to a surface of the associated magnet. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention provides a magnetic field sensor arrangement for which a magnetic field sensor is positioned such that a magnetic field sensing element therein has an axis of sensitivity not parallel to a surface of an associated magnet. 
         [0013]    In accordance with one aspect of the present invention, a magnetic field sensor arrangement includes a magnet having two opposing surfaces separated by a magnet thickness and having at least one north pole disposed proximate to at least one south pole. A line between a center of the at least one north pole and a center of the at least one south pole lies in an x-y plane. The magnetic field sensor arrangement also includes a magnetic field sensor comprising a magnetic field sensing element with a center and with at least one major response axis disposed in a major response plane intersecting the magnetic field sensing element. The magnetic field sensor is disposed proximate to the magnet with the major response plane within forty-five degrees of perpendicular to the x-y plane. 
         [0014]    In another aspect of the present invention, a method of sensing a movement of an object includes attaching to the object a magnet having two opposing surfaces separated by a magnet thickness and having at least one north pole disposed proximate to at least one south pole. A line between a center of the at least one north pole and a center of the at least one south pole lies in an x-y plane. The method also includes placing proximate to the magnet a magnetic field sensor comprising a magnetic field sensing element with a center and with at least one major response axis disposed in a major response plane intersecting the magnetic field sensing element. The magnetic field sensor is disposed with the major response plane within forty-five degrees of perpendicular to the x-y plane. 
         [0015]    With these arrangements, mechanical arrangements are provided that achieve a good sensitivity that would not be generally apparent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The foregoing features of the invention, as well as the invention itself may be more fully understood from the following detailed description of the drawings, in which: 
           [0017]      FIG. 1  is a pictorial showing a circular vertical Hall (CVH) sensing element having a plurality of vertical Hall elements arranged in a circle over a common implant region in a substrate and a two pole ring magnet disposed close to the CVH sensing element; 
           [0018]      FIG. 1A  is a pictorial showing a plurality of magnetic field sensing elements, for example, vertical Hall elements or magnetoresistance elements, upon a substrate; 
           [0019]      FIG. 1B  is a pictorial showing a magnetic field sensing element upon a substrate; 
           [0020]      FIG. 2  is a graph showing an output signal as may be generated by the CVH sensing element of  FIG. 1  or by the magnetic field sensing elements of  FIG. 1A ; 
           [0021]      FIG. 3  is a block diagram showing an electronic circuit using a CVH sensing element to determine a direction of a sensed magnetic field; 
           [0022]      FIG. 4  is a pictorial showing a magnetic field sensor arrangement having a magnetic field sensor proximate to a ring magnet configured to rotate; 
           [0023]      FIG. 5  is a pictorial showing another magnetic field sensor arrangement having a magnetic field sensor proximate to a ring magnet configured to rotate; 
           [0024]      FIGS. 6-8  are graphs showing behaviors of the magnetic field sensor arrangement of  FIG. 4 ; 
           [0025]      FIGS. 9-11  are graphs showing behaviors of the magnetic field sensor arrangement of  FIG. 5 ; and 
           [0026]      FIG. 12  is a pictorial of another magnetic field sensor arrangement having a magnetic field sensor proximate to line magnet configured to move linearly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Before describing the present invention, some introductory concepts and terminology are explained. 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 elements can be, but are not limited to, Hall effect elements, magnetoresistance elements, or magnetotransistors. As is known, there are different types of Hall effect elements, for example, a planar Hall element, a vertical Hall element, and a circular Hall element. As is also known, there are different types of magnetoresistance elements, for example, a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, an Indium antimonide (InSb) sensor, and a magnetic tunnel junction (MTJ). 
         [0028]    As used herein, the term “sensor” is used to describe a circuit or assembly that includes a sensing element and other components. In particular, as used herein, the term “magnetic field sensor” is used to describe a circuit or assembly that includes a magnetic field sensing element and electronics coupled to the magnetic field sensing element. 
         [0029]    As used herein, the term “center” is used to indicate a point equidistant from or at the average distance from all points on the sides or outer boundaries of an object, which may be a three dimensional object. Unless otherwise specified, the term “center” is used in a three-dimensional sense to indicate a three dimensional center. 
         [0030]    As is known, some of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity parallel to a substrate that supports the magnetic field sensing element, and others of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity perpendicular to a substrate that supports the magnetic field sensing element. In particular, planar Hall elements tend to have axes of sensitivity perpendicular to a substrate, while magnetoresistance elements and vertical Hall elements (including circular vertical Hall (CVH) sensing elements) tend to have axes of sensitivity parallel to a substrate. 
         [0031]    Magnetic field sensors are used in a variety of applications, including, but not limited to, an angle sensor that senses an angle of a direction 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, and a magnetic field sensor that senses a magnetic field density of a magnetic field. 
         [0032]    While a circular vertical Hall (CVH) magnetic field sensing element, which has a plurality of vertical Hall magnetic field sensing elements, is described in examples below, it should be appreciated that the same or similar techniques apply to any type of magnetic field sensing elements and to any type of magnetic field sensors. In particular, techniques apply to one or more separate vertical Hall elements or separate magnetoresistance elements, not arranged in a CVH structure, and with or without associated electronic circuits. 
         [0033]    Referring to  FIG. 1 , a circular vertical Hall (CVH) sensing element  12  includes a circular implant region  18  having a plurality of vertical Hall elements disposed thereon, of which a vertical Hall element  12   a  is but one example. Each vertical Hall element has a plurality of Hall element contacts (e.g., four or five contacts), of which a vertical Hall element contact  12   aa  is but one example. 
         [0034]    A particular vertical Hall element (e.g.,  12   a ) within the CVH sensing element  12 , which, for example, can have five adjacent contacts, can share some, for example, four, of the five contacts with a next vertical Hall element (e.g.,  12   b ). Thus, a next vertical Hall element can be shifted by one contact from a prior vertical Hall element. For such shifts by one contact, it will be understood that the number of vertical Hall elements is equal to the number of vertical Hall element contacts, e.g.,  32 . However, it will also be understood that a next vertical Hall element can be shifted by more than one contact from the prior vertical Hall element, in which case, there are fewer vertical Hall elements than there are vertical Hall element contacts in the CVH sensing element. 
         [0035]    A center of a vertical Hall element  0  is positioned along an x-axis  20  and a center of vertical Hall element  8  is positioned along a y-axis  22 . In the exemplary CVH  12 , there are thirty-two vertical Hall elements and thirty-two vertical Hall element contacts. However, a CVH can have more than or fewer than thirty-two vertical Hall elements and more than or fewer than thirty-two vertical Hall element contacts. 
         [0036]    In some applications, a circular magnet  14  having a south side  14   a  and a north side  14   b  can be disposed over the CVH  12 . The circular magnet  14  tends to generate a magnetic field  16  having a direction from the north side  14   a  to the south side  14   b , here shown to be pointed to a direction of about forty-five degrees relative to x-axis  20 . Other magnets having other shapes and configurations are possible. 
         [0037]    In some applications, the circular magnet  14  is mechanically coupled to a rotating object (a target object), for example, an automobile crank shaft or an automobile camshaft, and is subject to rotation relative to the CVH sensing element  12 . With this arrangement, the CVH sensing element  12  in combination with an electronic circuit described below can generate a signal related to the angle of rotation of the magnet  14 . 
         [0038]    The CVH sensing element  12  can be disposed upon a substrate  26 , for example, a silicon substrate, along with other electronics (not shown). 
         [0039]    A center  24  of the CVH sensing element  12  is at a center of the entire CVH sensing element  12 . Since the CVH sensing element  12  has very little depth (into the page), the center  24  can be considered to be on the surface of the substrate  26 . 
         [0040]    Referring now to  FIG. 1A , a plurality of magnetic field sensing elements  30   a - 30   h  (or alternatively, sensors), in a general case, can be any type of magnetic field sensing elements. The magnetic field sensing elements  30   a - 30   h  can be, for example, planar Hall elements, vertical Hall elements, or magnetoresistance elements. These elements can also be coupled to an electronic circuit described below. For embodiments where the sensing elements  30   a - 30   h  are vertical Hall elements or magnetoresistance elements, there can also be a magnet the same as or similar to the magnet  14  of  FIG. 1 , disposed proximate to the sensing elements  30   a - 30   h  in the same way as is shown in  FIG. 1 . 
         [0041]    The group of sensing elements  30   a - 30   h  can be disposed upon a substrate  34 , for example, a silicon substrate, along with other electronics (not shown). 
         [0042]    A center  32  of the plurality of magnetic field sensing elements  30   a - 30   h  is at a center of the entire group of magnetic field sensing elements  30   a - 30   h . Since the magnetic field sensing elements  30   a - 30   h  have very little depth (into the page), the center  32  can be considered to be on the surface of the substrate  34 . 
         [0043]    Referring now to  FIG. 1B , a magnetic field sensing element  40  can be a single element, for example, a single vertical Hall element or a single magnetoresistance element, disposed upon a substrate  44  along with other electronics (not shown). 
         [0044]    A center  42  of the magnetic field sensing element  40  is at a center of the magnetic field sensing element  40 . Since the magnetic field sensing element has very little depth (into the page), the center  42  can be considered to be on the surface of the substrate  44 . 
         [0045]    Referring now to  FIG. 2 , a graph  50  has a horizontal axis with a scale in units of CVH vertical Hall element position, n, around a CVH sensing element, for example, the CVH sensing element  12  of  FIG. 1 . The graph  50  also has a vertical axis with a scale in amplitude in units of millivolts. 
         [0046]    The graph  50  includes a signal  52  representative of output signal levels from the plurality of vertical Hall elements of the CVH taken sequentially with the magnetic field of  FIG. 1  stationary and pointing in a direction of forty-five degrees. 
         [0047]    Referring briefly to  FIG. 1 , as described above, vertical Hall element  0  is centered along the x-axis  20  and vertical Hall element  8  is centered along the y-axis  22 . In the exemplary CVH sensing element  12 , there are thirty-two vertical Hall element contacts and a corresponding thirty-two vertical Hall elements, each vertical Hall element having a plurality of vertical Hall element contacts, for example, five contacts. 
         [0048]    In  FIG. 2 , a maximum positive signal is achieved from a vertical Hall element centered at position  4 , which is aligned with the magnetic field  16  of  FIG. 1 , such that a line drawn between the vertical Hall element contacts (e.g., five contacts) of the vertical Hall element at position  4  is perpendicular to the magnetic field. A maximum negative signal is achieved from a vertical Hall element centered at position  20 , which is also aligned with the magnetic field  16  of  FIG. 1 , such that a line drawn between the vertical Hall element contacts (e.g., five contacts) of the vertical Hall element at position  20  is also perpendicular to the magnetic field. 
         [0049]    A sine wave  54  is provided to more clearly show the ideal behavior of the signal  52 . The signal  52  has variations due to vertical Hall element offsets, which tend to somewhat randomly cause element output signals to be too high or too low relative to the sine wave  54 , in accordance with offset errors for each element. The offset signal errors are undesirable. In some embodiments, the offset errors can be reduced by “chopping” each vertical Hall element. 
         [0050]    Chopping will be understood to be a process by which vertical Hall element contacts of each vertical Hall element are driven in different configurations and signals are received from different ones of the vertical Hall element contacts of each vertical Hall element to generate a plurality of output signals from each vertical Hall element. The plurality of signals can be arithmetically processed (e.g., summed or otherwise averaged) resulting in a signal with less offset. 
         [0051]    Full operation of the CVH sensing element  12  of  FIG. 1  and generation of the signal  52  of  FIG. 2  are described in more detail in the above-described PCT Patent Application No. PCT/EP2008/056517, entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, which is published in the English language as PCT Publication No. WO 2008/145662. 
         [0052]    As will be understood from PCT Patent Application No. PCT/EP2008/056517, groups of contacts of each vertical Hall element can be used in a multiplexed or chopped arrangement to generate chopped output signals from each vertical Hall element. Thereafter, or in parallel (i.e., at the same time), a new group of adjacent vertical Hall element contacts can be selected (i.e., a new vertical Hall element), which can be offset by one or more elements from the prior group. The new group can be used in the multiplexed or chopped arrangement to generate another chopped output signal from the next group, and so on. 
         [0053]    Each step of the signal  52  can be representative of a chopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. However, in other embodiments, no chopping is performed and each step of the signal  52  is representative of an unchopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. Thus, the graph  52  is representative of a CVH output signal with or without the above-described grouping and chopping of vertical Hall elements. 
         [0054]    It will be understood that, using techniques described above in PCT Patent Application No. PCT/EP2008/056517, a phase of the signal  52  (e.g., a phase of the signal  54 ) can be found and can be used to identify the pointing direction of the magnetic field  16  of  FIG. 1  relative to the CVH sensing element  12 . 
         [0055]    Referring now to  FIG. 3 , a magnetic field sensor  70  includes a sensing portion  71 . The sensing portion  71  can include a CVH sensing element  72  having a plurality of CVH sensing element contacts, e.g., a CVH sensing element contact  73 . In some embodiments there are thirty-two vertical Hall elements in the CVH sensing element  72  and a corresponding thirty-two CVH sensing element contacts. In other embodiments there are sixty-four vertical Hall elements in the CVH sensing element  72  and a corresponding sixty-four CVH sensing element contacts. However, a CVH sensing element can have more than or fewer than thirty-two vertical Hall elements and more than or fewer than thirty-two CVH sensing element contacts. 
         [0056]    A magnet (not shown) can be disposed proximate to the CVH sensing element  72 , and can be coupled to a target object (not shown). The magnet can be the same as or similar to the magnet  14  of  FIG. 1   
         [0057]    As described above, the CVH sensing element  72  can have a plurality of vertical Hall elements, each vertical Hall element comprising a group of vertical Hall element contacts (e.g., five vertical Hall element contacts), of which the vertical Hall element contact  73  is but one example. 
         [0058]    In some embodiments, a switching circuit  74  can provide sequential CVH differential output signals  72   a ,  72   b  from the CVH sensing element  72 . 
         [0059]    The CVH differential output signal  72   a ,  72   b  is comprised of sequential output signals taken one-at-a-time around the CVH sensing element  72 , wherein each output signal is generated on a separate signal path and switched by the switching circuit  74  into the path of the differential output signal  72   a ,  72   b . The signal  52  of  FIG. 2  can be representative of the differential signal  72   a ,  72   b . Therefore, the CVH differential output signal  72   a ,  72   b  can be represented as a switched set of CVH output signals x n =x 0  to x N-1 , taken one at a time, where n is equal to a vertical Hall element position (i.e., a position of a group of vertical Hall element contacts that form a vertical Hall element) in the CVH sensing element  72 , and where there are N such positions. 
         [0060]    In one particular embodiment, the number of vertical Hall elements (each comprising a group of vertical Hall element contacts) in the CVH sensing element  72  is equal to the total number of sensing element positions, N. In other words, the CVH differential output signal  72   a ,  72   b  can be comprised of sequential output signals, wherein the CVH differential output signal  72   a ,  72   b  is associated with respective ones of the vertical Hall elements in the CVH sensing element  72  as the switching circuit  74  steps around the vertical Hall elements of the CVH sensing element  72  by increments of one, and N equals the number of vertical Hall elements in the CVH sensing element  72 . However, in other embodiments, the increments can be by greater than one vertical Hall element, in which case N is less than the number of vertical Hall elements in the CVH sensing element  72 . 
         [0061]    In one particular embodiment, the CVH sensing element  72  has thirty-two vertical Hall elements, i.e., N=32, and each step is a step of one vertical Hall element contact position (i.e., one vertical Hall element position). However, in other embodiments, there can be more than thirty-two or fewer than thirty-two vertical Hall elements in the CVH sensing element  72 , for example sixty-four vertical Hall elements. Also, the increments of vertical Hall element positions, n, can be greater than one vertical Hall element contact. 
         [0062]    In some embodiments, another switching circuit  76  can provide the above-described “chopping” of groups of the vertical Hall elements within the CVH sensing element  72 . Chopping will be understood to be an arrangement in which a group of vertical Hall element contacts, for example, five vertical Hall element contacts that form one vertical Hall element, are driven with current sources  86  in a plurality of different connection configurations, and signals are received from the group of vertical Hall element contacts in corresponding different configurations to generate the CVH differential output signal  72   a ,  72   b . Thus, in accordance with each vertical Hall element position, n, there can be a plurality of sequential output signals during the chopping, and then the group increments to a new group, for example, by an increment of one vertical Hall element contact. 
         [0063]    The sensing portion  71  can also include current sources  86  configured to drive the CVH sensing element  72  when the CVH sensing element  72 . 
         [0064]    While current sources  86  are shown, in other embodiments, the current sources  86  can be replaced by voltage sources. 
         [0065]    The magnetic field sensor  70  includes an oscillator  78  that provides clock signals  78   a ,  78   b ,  78   c , which can have the same or different frequencies. A divider  80  is coupled to receive the clock signal  78   a  and configured to generate a divided clock signal  80   a . A switch control circuit  82  is coupled to receive the divided clock signal  80   a  and configured to generate switch control signals  82   a , which are received by the switching circuits  74 ,  76  to control the sequencing around the CVH sensing element  72 , and optionally, to control the chopping of groups of vertical Hall elements within the CVH sensing element  72  in ways described above. 
         [0066]    The magnetic field sensor  70  can include a divider  88  coupled to receive the clock signal  78   c  and configured to generate a divided clock signal  88   a , also referred to herein as an “angle update clock” signal. 
         [0067]    The magnetic field sensor  70  also includes an x-y direction component circuit  90 . The x-y direction component circuit  90  can include an amplifier  92  coupled to receive the CVH differential output signals  72   a ,  72   b . The amplifier  92  is configured to generate an amplified signal  92   a . A bandpass filter  94  is coupled to receive the amplified signal  92   a  and configured to generate a filtered signal  94   a . A comparator  96 , with or without hysteresis, is configured to receive the filtered signal  94   a . The comparator  96  is also coupled to receive a threshold signal  120 . The comparator  96  is configured to generate a thresholded signal  96   a  generated by comparison of the filtered signal  94   a  with the threshold signal  120 . 
         [0068]    The x-y direction component circuit  90  also includes an amplifier  114  coupled to receive the divided clock signal  88   a . The amplifier  114  is configured to generate an amplified signal  114   a . A bandpass filter  116  is coupled to receive the amplified signal  114   a  and configured to generate a filtered signal  116   a . A comparator  118 , with or without hysteresis, is coupled to receive the filtered signal  116   a . The comparator  118  is also coupled to receive a threshold signal  122 . The comparator  118  is configured to generate a thresholded signal  118   a  by comparison of the filtered signal  116   a  with the threshold signal  122 . 
         [0069]    The bandpass filters  94 ,  116  can have center frequencies equal to I/T, where T is the time that it takes to sample all of the vertical Hall elements within the CVH sensing element  72 . 
         [0070]    It should be understood that the amplifier  114 , the bandpass filter  116 , and the comparator  118  provide a delay of the divided clock signal  88   a  in order to match a delay of the circuit channel comprised of the amplifier  92 , the bandpass filter  94 , and the comparator  96 . The matched delays provide phase matching, in particular, during temperature excursions of the magnetic field sensor  70 . 
         [0071]    A counter  98  can be coupled to receive the thresholded signal  96   a  at an enable input, to receive the clock signal  78   b  at a clock input, and to receive the thresholded signal  118   a  at a reset input. 
         [0072]    The counter  98  is configured to generate a phase signal  98   a  having a count representative of a phase difference between the thresholded signal  96   a  and the thresholded signal  118   a.    
         [0073]    The phase shift signal  98   a  is received by a latch  100  that is latched upon an edge of the divided clock signal  88   a . The latch  100  is configured to generate a latched signal  100   a , also referred to herein as an “x-y angle signal.” 
         [0074]    It will be apparent that the latched signal  100   a  is a multi-bit digital signal that has a value representative of a direction of an angle of the magnetic field experience by the CVH sensing element  72 , and thus, an angle of the magnet and target object. 
         [0075]    In some embodiments, the clock signals  78   a ,  78   b ,  78   c  each have a frequency of about 30 MHz, the divided clock signal  80   a  has a frequency of about 8 MHz, and the angle update clock signal  88   a  has a frequency of about 30 kHz. However in other embodiments, the initial frequencies can be higher or lower than these frequencies 
         [0076]    With the magnetic field sensor  70 , it will be appreciated that an update rate of the x-y angle signal  100   a  occurs at a rate equivalent to a rate at which all of the vertical Hall elements within the CVH sensing element  72  are collectively sampled. 
         [0077]    Referring now to  FIG. 4 , a magnetic field sensor arrangement  120  includes a magnet  126  (e.g., a ring magnet) having two opposing surfaces  126   a ,  126   b  separated by a magnet thickness. In some embodiments, the surfaces  126   a ,  126   b  are flat and/or parallel. However, in other embodiments, the surfaces  126   a ,  126   b  of the magnet  126  can be irregular. 
         [0078]    The magnet  126  has at least one north pole and at least one south pole, but can have a plurality of north poles and/or a plurality of south poles. A line (not shown) between a center of the at least one north pole and a center of the at least one south pole lies in an x-y plane (axes shown). 
         [0079]    The magnet  126  can be coupled to a target object  128 , for example, a shaft configured to rotate. 
         [0080]    A magnetic field sensor  122  has a magnetic field sensing element (not shown) disposed therein upon a substrate (not shown). The magnetic field sensor  122  can be comprised of circuits the same as or similar to the magnetic field sensor  70  of  FIG. 3 . 
         [0081]    The magnetic field sensor  122  can have leads, of which a lead  124  is but one example, which are configured to couple to or solder to a circuit board (not shown). The magnetic field sensor and magnetic field sensing element therein have at least one major response axis  125  disposed in a major response plane (e.g., parallel to the x-y plane) in which direction the magnetic field sensing element is most sensitive and perpendicular to which the magnetic field sensing element has little or no sensitivity. 
         [0082]    It will be understood from discussion above that a CVH sensing element has a plurality of major response axes disposed in a major response plane. 
         [0083]    In the magnetic field sensor arrangement  120 , the magnetic field sensor  122  is disposed relative to the magnet  126  in an orientation as shown, such that the major response axis  125  is disposed in a major response plane parallel to and between planes of the first and second surfaces  126   a ,  126   b , respectively. 
         [0084]    In other embodiments, the magnetic field sensor  122  is disposed so that the major response axis  125  does not pass between planes of the first and second surfaces  126   a ,  126   b.    
         [0085]    The magnetic field sensor  122  is disposed at a distance  130  away from an edge of the magnet  126 . 
         [0086]    Magnetic field lines, of which a magnetic field line  132  is but one example, take a variety of paths from the north pole to the south pole, but at the edge of the magnet  126  generally follow a circuitous path from the north pole to the south pole. The magnetic field line  132  is representative of a portion of one of the circuitous paths. The magnetic field sensor  122  is responsive to the magnetic field, e.g.,  132 . 
         [0087]    The magnetic field sensor  122  is disposed such that the distance  130  is small and such that the magnetic field line  132  passes through the magnetic field sensor  122  and with a direction generally parallel to the major response axis  125 . 
         [0088]    In other embodiments, the magnet  126  has a plurality of north poses and a plurality of south poles. 
         [0089]    It will be recognized that, a smaller distance  130  results in a higher magnetic field sensed by the magnetic field sensor  122  and magnetic field sensing elements therein. However, this orientation of the magnetic field sensor  122 , particularly when coupled to a circuit board (not shown), results in a comparatively large distance  130  between the magnetic field sensor  122 , and in particular, the magnetic field sensing element (not shown) within the magnetic field sensor  122 , and the magnet  126 . 
         [0090]    Referring now to  FIG. 5 , a magnetic field sensor arrangement  140  includes a magnet  146  (e.g., a ring magnet) having two opposing surfaces  146   a ,  146   b  separated by a magnet thickness and having at least one north pole (N) disposed proximate to at least one south pole (S). In some embodiments, the surfaces  146   a ,  146   b  are flat and/or parallel. However, in other embodiments, the surfaces  146   a ,  146   b  of the magnet  146  can be irregular. 
         [0091]    A line (not shown) between a center of the at least one north pole and a center of the at least one south pole lies in an x-y plane (axes shown). 
         [0092]    The magnet  146  can be coupled to a target object  148 , for example, a shaft configured to rotate. 
         [0093]    A magnetic field sensor  144  has a magnetic field sensing element (not shown) with a center and with at least one major response axis  145  disposed in a major response plane intersecting the magnetic field sensing element. The magnetic field sensor  144  can be comprised of circuits the same as or similar to the magnetic field sensor  70  of  FIG. 3 . The magnetic field sensor  144  is disposed proximate to the magnet  146  with the major response axis  145  and major response plane within about forty-five degrees of perpendicular to the x-y plane. In some embodiments, the major response axis  145  and major response plane are perpendicular to the x-y plane. 
         [0094]    It will be understood from discussion above that a CVH sensing element has a plurality of major response axes disposed in a major response plane. 
         [0095]    In some embodiments, the center of the magnetic field sensing element within the magnetic field sensor  144  is disposed in a plane parallel to and between the two opposing surfaces  146   a ,  146   b.    
         [0096]    In other embodiments as shown, the center of the magnetic field sensing element is disposed in a plane parallel to and not between the two opposing surfaces  146   a ,  146   b.    
         [0097]    The magnetic field sensing element within the magnetic field sensor  144  is disposed at a distance  150  from an edge of the magnet  146  in a y direction, and at a distance  154  in the z direction. The distance  150  can be smaller than the distance  130  of  FIG. 4 . 
         [0098]    Magnetic field lines, of which a magnetic field line  152  is but one example, take a variety of paths from the north pole to the south pole. The magnetic field line  152  is the same as or similar to the magnetic field line  132  of  FIG. 4 . The magnetic field sensor  144  is responsive to the magnetic field, e.g.,  152 , generated by the magnet  146 . 
         [0099]    It will be recognized that the magnetic field sensor  144  can be disposed at a position such that magnetic field lines, e.g., the magnetic field line  152 , passes through the magnetic field sensor  144 , and, in particular, through the magnetic field sensing element within the magnetic field sensor  144 , in a direction parallel to the major response axis  145  and to the major response plane, accordingly. 
         [0100]    In other embodiments, the magnet  146  has a plurality of north poses and a plurality of south poles. 
         [0101]    It is desirable that the magnetic field sensor  144  behaves with a sensitivity and with an error the same as or similar to the magnetic field sensor  122  of  FIG. 4 . Graphs shown below in  FIGS. 6-8  show sensitivity and errors for the magnetic field sensor arrangement  120  of  FIG. 4 . Graphs shown below in  FIGS. 9-11  show sensitivity and errors for the magnetic field sensor arrangement  140  of  FIG. 5 . 
         [0102]    Referring now to  FIG. 6 , a graph  150  has a horizontal axis with a scale in units of angular rotation in degrees of a magnet, for example, the magnet  126  of  FIG. 4 . The graph  150  also includes a vertical axis with a scale in units of magnetic field in teslas in an x-y plane, for example, the x-y plane of  FIG. 4 . 
         [0103]    Curves  152 - 170  are representative of magnetic fields experienced by a magnetic field sensor, for example, the magnetic field sensor  122  of  FIG. 4 , and in particular, a magnetic field sensing element within the magnetic field sensor  122 , for different positions of the magnetic field sensor  122  in a z-direction (see axes in  FIG. 4 ) as the magnet  126  rotates. To generate the curves  152 - 170 , it is presumed that the magnet  126  of  FIG. 4  has one north pole and one south pole. It is also presumed that the distance  130  of  FIG. 4  is about 1 mm. It is also presumed that the magnet  126  has a thickness between the first and second surfaces  126   a ,  126   b  of about 3 mm. 
         [0104]    The curve  152  is representative of a position of the magnetic field sensor  122  in the z-direction corresponding to zero millimeters, which is equivalent to the magnetic field sensor (i.e., the magnetic field sensing element within the magnetic field sensor  122 ) being centered upon the y-axis, which is midway between the first and second opposing surfaces  126   a ,  126   b  of the magnet  126 . 
         [0105]    The remaining curves  154 - 170  are representative of positions of the magnetic field sensing element in increments of 0.5 millimeters, respectively, in the z-direction of  FIG. 4 . 
         [0106]    The curve  162 , which corresponds to a z-direction position of 2.5 millimeters, has a small but uniform magnetic field amplitude over the 360 degrees rotation of the magnet. 
         [0107]    Referring now to  FIG. 7 , a graph  180  has a horizontal axis with a scale in units of angular rotation in degrees of a magnet, for example, the magnet  126  of  FIG. 4 . The graph  150  also includes a vertical axis with a scale in units of estimated angular error in degrees. 
         [0108]    Curves  182 - 200  are representative of angular errors of pointing directions of sensed magnetic fields versus rotation angle of the magnet  126  at a variety of positions of the magnetic field sensor  122  of  FIG. 4 , specifically for different positions of the magnetic field sensor circuit in a z-direction (see axes in  FIG. 4 ) as the magnet  126  rotates. To generate the curves  182 - 200 , it is again presumed that the magnet  126  of  FIG. 4  has one north pole and one south pole. It is also presumed that the distance  130  of  FIG. 4  is about 1 mm. It is also presumed that the magnet  126  has a thickness between the first and second surfaces  126   a ,  126   b  of about 3 mm. 
         [0109]    The curve  182  (hidden behind the curve  184 ) is representative of a position of the magnetic field sensor  122  in the z-direction corresponding to zero millimeters, which is equivalent to the magnetic field sensor (i.e., the magnetic field sensing element within the magnetic field sensor  122 ) being centered upon the y-axis, which is midway between the first and second opposing surfaces  126   a ,  126   b  of the magnet  126 . 
         [0110]    The remaining curves  184 - 200  are representative of positions of the magnetic field sensing element in increments of 0.5 millimeters in the z-direction of  FIG. 4 . It can be seen that the curve  192  has a lowest angular error of about +/−four degrees. The curve  192  corresponds to an offset in the z-direction of 2.5 millimeters and corresponds to the curve  162  of  FIG. 6 . 
         [0111]    Referring now to  FIG. 8 , a graph  210  has a horizontal axis with a scale in units of angular rotation in degrees of a magnet, for example, the magnet  126  of  FIG. 4 . The graph  210  also includes a vertical axis with a scale in units of estimated angular error in degrees. 
         [0112]    Curves  212 - 222  are representative of angular errors of pointing directions of sensed magnetic fields versus rotation angle of the magnet  126  at a variety of positions of the magnetic field sensor  122  of  FIG. 4 , specifically for different positions of the magnetic field sensor  122  in the y-direction (see axes in  FIG. 4 ) as the magnet  126  rotates. To generate the curves  212 - 222 , it is again presumed that the magnet  126  of  FIG. 4  has one north pole and one south pole. 
         [0113]    It is also presumed that the magnet  126  has a thickness between the first and second surfaces  126   a ,  126   b  of about 3 mm. 
         [0114]    The curve  212  is representative of a position of the magnetic field sensor  122  (i.e., the magnetic field sensing element within the magnetic field sensor  122 ) in the y-direction corresponding to one millimeter, and centered midway between the first and second opposing surfaces  126   a ,  126   b  of the magnet  126 . The curves  212 - 222  are generated for the z-direction position of the magnetic field sensor  122  (i.e., the magnetic field sensing element within the magnetic field sensor  122 ) of zero millimeters, corresponding to positions of the magnetic field sensor  122  to generate the curve  152  of  FIG. 6  and curve  182  of  FIG. 7 . 
         [0115]    The remaining curves  214 - 222  are representative of positions of the magnetic field sensing element in increments of 0.5 millimeters in the x-direction of  FIG. 4 . It can be seen that the curves  214 - 222  have roughly equivalent errors. Thus, it should be appreciated that movement or placement error of the magnetic field sensor  122  in the direction of the y-axis (i.e., changes of air gap) does not affect the accuracy of the sensed magnetic field very much. 
         [0116]    Referring now to  FIG. 9 , a graph  240  has a horizontal axis with a scale in units of angular rotation in degrees of a magnet, for example, the magnet  146  of  FIG. 5 . The graph  240  also includes a vertical axis with a scale in units of magnetic field in teslas in an x-z plane, for example, the x-y plane of  FIG. 5 . 
         [0117]    Curves  242 - 260  are representative of magnetic fields experienced by a magnetic field sensor, for example, the magnetic field sensor  144  of  FIG. 5 , and in particular, a magnetic field sensing element within the magnetic field sensor  144 , for different positions of the magnetic field sensor  144  in a z-direction (see axes in  FIG. 5 ) as the magnet  146  rotates. To generate the curves  242 - 260 , it is presumed that the magnet  146  of  FIG. 5  has one north pole and one south pole. It is also presumed that the distance  150  of  FIG. 5  is about 1 mm. It is also presumed that the magnet  146  has a thickness between the first and second surfaces  146   a ,  146   b  of about 3 mm. 
         [0118]    The curve  242  is representative of a position of the magnetic field sensor  144  in the z-direction corresponding to zero millimeters, which is equivalent to the magnetic field sensor  144  (i.e., the magnetic field sensing element within the magnetic field sensor  144 ) being centered upon the y-axis, which is midway between the first and second opposing surfaces  146   a ,  146   b  of the magnet  146 . 
         [0119]    The remaining curves  244 - 260  are representative of positions of the magnetic field sensing element in increments of 0.5 millimeters in the z-direction of  FIG. 5 . 
         [0120]    The curve  246 , which corresponds to a z-direction position of 1.0 millimeters, is the curve with the smallest magnetic field amplitude, leading to an optimal position in terms of sensor resolution. 
         [0121]    Referring now to  FIG. 10 , a graph  270  has a horizontal axis with a scale in units of angular rotation in degrees of a magnet, for example, the magnet  146  of  FIG. 5 . The graph  270  also includes a vertical axis with a scale in units of estimated angular error in degrees. 
         [0122]    Curves  272 - 290  are representative of angular errors of pointing directions of sensed magnetic fields versus rotation angle of the magnet  146  at a variety of positions of the magnetic field sensor  144  of  FIG. 5 , specifically for different positions of the magnetic field sensor  144  in a z-direction (see axes in  FIG. 5 ) as the magnet  146  rotates. To generate the curves  272 - 290 , it is again presumed that the magnet  146  of  FIG. 5  has one north pole and one south pole. It is also presumed that the distance  150  of  FIG. 5  is about 1 mm. It is also presumed that the magnet  146  has a thickness between the first and second surfaces  146   a ,  146   b  of about 3 mm. 
         [0123]    The curve  272  is representative of a position of the magnetic field sensor  144  in the z-direction corresponding to zero millimeters, which is equivalent to the magnetic field sensor  144  (i.e., the magnetic field sensing element within the magnetic field sensor  144 ) being centered upon the y-axis, which is midway between the first and second opposing surfaces  146   a ,  146   b  of the magnet  146 . At the position represented by the curve  272 , errors of the magnetic field sensor  144  are high due to the absence or near absence of a magnetic field in the maximum response direction  145 . 
         [0124]    The remaining curves  274 - 290  are representative of positions of the magnetic field sensing element in increments of 0.5 millimeters in the z-direction of  FIG. 5 . It can be seen that the curve  276  has a lowest angular error of about +/−eight degrees. The curve  276  corresponds to an offset in the z-direction of 1.0 millimeters and corresponds to the curve  246  of  FIG. 9 . 
         [0125]    Referring now to  FIG. 11 , a graph  300  has a horizontal axis with a scale in units of angular rotation in degrees of a magnet, for example, the magnet  146  of  FIG. 5 . The graph  300  also includes a vertical axis with a scale in units of estimated angular error in degrees. 
         [0126]    Curves  302 - 312  are representative of angular errors of pointing directions of sensed magnetic fields versus rotation angle of the magnet  146  at a variety of positions of the magnetic field sensor  144  of  FIG. 5 , specifically for different positions of the magnetic field sensor  144  in a y-direction (see axes in  FIG. 5 ) as the magnet  146  rotates. To generate the curves  302 - 312 , it is again presumed that the magnet  146  of  FIG. 5  has one north pole and one south pole. It is also presumed that the magnet  146  has a thickness between the first and second surfaces  146   a ,  146   b  of about 3 mm. 
         [0127]    The curve  302  is representative of a position of the magnetic field sensor  144  (i.e., the magnetic field sensing element within the magnetic field sensor  144 ) in the y-direction corresponding to zero millimeters, and shifted 1.5 mm along the z-axis from the center position between the first and second opposing surfaces  146   a ,  146   b  of the magnet  146 . The curves  302 - 312  are generated for the z-direction position of the magnetic field sensor  144  of 1.5 millimeters, corresponding to positions of the magnetic field sensor  144  to generate the curve  248  of  FIG. 9  and curve  278  of  FIG. 10 . 
         [0128]    The remaining curves  304 - 312  are representative of positions of the magnetic field sensing element in increments of 0.5 millimeters in the y-direction of  FIG. 5 . It can be seen that the curves  214 - 222  do not have equivalent errors. Thus, it should be appreciated that movement or placement error of the magnetic field sensor  144  in the direction of the y-axis (i.e., changes of air gap) does affect the accuracy of the sensed magnetic field. 
         [0129]    By comparison of  FIGS. 6-8  with  FIGS. 9-11 , it can be seen that the magnetic field sensor arrangement  140  of  FIG. 5  can achieve similar or better accuracies than the magnetic field sensor arrangement  120  of  FIG. 4 . 
         [0130]    Referring now to  FIG. 12 , a magnetic field sensor arrangement  320  includes a magnet  326  having two opposing surfaces  326   a ,  326   b  separated by a magnet thickness. The magnet  326  has at least one north pole and at least one south pole, but can have a plurality of north poles and/or a plurality of south poles as shown. 
         [0131]    The magnet  326  can be coupled to a target object (not shown). 
         [0132]    A magnetic field sensor  322  has a magnetic field sensing element (e.g., a CVH sensing element  323 ) with a center and with at least one major response axis  324  disposed in a major response plane (e.g., parallel to a y-z plane) intersecting the magnetic field sensing element  323 . The magnetic field sensor  324  is disposed proximate to the magnet  326  with the major response plane within forty-five degrees of perpendicular to an x-y plane. In some embodiments, the major response plane is perpendicular to the x-y plane. 
         [0133]    In some embodiments as shown, a center of the magnetic field sensing element (e.g.,  323 ) is disposed in a plane parallel to and not between the two opposing surfaces  326   a ,  326   b . However, in other embodiments, the center of the magnetic field sensing element is disposed in a plane between the two opposing surfaces  326   a ,  322   b.    
         [0134]    Magnetic field lines, of which a magnetic field line  330  is but one example, take a variety of paths from a north pole to the south pole. The magnetic field sensor  322  is responsive to the magnetic field, e.g.,  330 , generated by the magnet  326 . 
         [0135]    It will be recognized that the magnetic field sensor  322  can be disposed at a position such that magnetic field lines, e.g., the magnetic field line  330 , passes through the magnetic field sensor  322 , and, in particular, through the magnetic field sensing element within the magnetic field sensor  322 , in a direction generally parallel to the major response axis  324 . 
         [0136]    With the magnetic field sensor arrangement  320 , a linear position of the magnet  326 , configured to move in directions  328 , can be sensed by the magnetic field sensor  322 . 
         [0137]    All references cited herein are hereby incorporated herein by reference in their entirety. 
         [0138]    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. 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.