Patent Publication Number: US-8542011-B2

Title: Apparatus and method for reducing a transient signal in a magnetic field sensor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of and claims the benefit of and priority to U.S. patent application Ser. No. 13/617,724, filed Sep. 14, 2012, which is a Continuation Application of and claims the benefit of and priority to U.S. patent application Ser. No. 12/900,969, filed Oct. 8, 2010, which applications are incorporated herein by reference in their entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
     Not Applicable. 
     FIELD OF THE INVENTION 
     This invention relates generally to magnetic field sensors and, more particularly, to a magnetic field sensor that includes features that can reduce a transient signal that would otherwise be generated when the magnetic field sensor is in the presence of a rapidly changing magnetic field. 
     BACKGROUND OF THE INVENTION 
     As is known magnetic field sensors can be used in a variety of applications. In one application, a magnetic field sensor can be used to sense an electrical current. One type of current sensor uses a Hall effect magnetic field sensing element in proximity to a current-carrying conductor. The Hall effect magnetic field sensing element generates an output signal having a magnitude proportional to the magnetic field induced by the current through the conductor. Typical current sensors of this type include a gapped toroid magnetic flux concentrator, with the Hall effect device positioned in a toroid gap. The Hall effect device and toroid are assembled in a housing, which is mountable on a printed circuit board. In use, a separate current-carrying conductor, such as a wire, is passed through the center of the toroid and is soldered to the printed circuit board, such as by soldering exposed ends of the wire to plated through-holes. 
     Other configurations of current sensors that use magnetic field sensing elements are known. Other configurations of current sensors are described in U.S. Pat. No. 6,781,359, issued Aug. 24, 2004 and U.S. Pat. No. 7,265,531, issued Sep. 4, 2007, both of which are assigned to the assignee of the present invention and both of which are incorporated by reference herein in their entireties. 
     Various parameters characterize the performance of current sensors, including sensitivity, which is the change in the output signal of a current sensor in response to a one ampere change through the conductor, and linearity, which is the degree to which the output signal of a current sensor varies in direct proportion to the current through the conductor. Important considerations in magnetic field sensors include the effect of stray magnetic fields and external magnetic noise on the sensor performance. 
     It has been observed that an output signal from a magnetic field sensor, for example, a current sensor, tends to have a transient “glitch” when the magnetic field sensor is exposed to a very high rate of change of magnetic field, for example, as may be generated by a very high rate of change of current in a current-carrying conductor. The source of this glitch has not been understood. 
     Techniques, such as filters, have been employed to remove this unwanted glitch. However, filters tend to slow down a desired edge rate otherwise available at the output of a magnetic field sensor. 
     It would be desirable to provide a magnetic field sensor, for example, a current sensor, which does not have the undesired glitch in the output signal when exposed to a rapidly changing magnetic field (or current). 
     SUMMARY OF THE INVENTION 
     The present invention provides a magnetic field sensor, for example, a current sensor, which does not have the undesired glitch in the output signal when exposed to a rapidly changing magnetic field (or current). 
     In accordance with one aspect of the present invention, a magnetic field sensor includes a lead frame having a base plate, a ground pin coupled to the base plate, and a signal output pin. The magnetic field sensor also includes a circuit die disposed upon the base plate. The circuit die includes a substrate. The circuit die also includes a magnetic field sensing element disposed upon the substrate and configured to generate a magnetic field signal responsive to a magnetic field. The circuit die also includes an output circuit disposed upon the substrate. The output circuit includes a circuit ground node and a circuit output node. The output circuit is configured to generate an output signal at the circuit output node responsive to the magnetic field signal. The circuit die also includes a ground circuit trace having first and second ends. The first end of the ground circuit trace is coupled to the circuit ground node. The circuit die also includes a ground bonding pad coupled to the second end of the ground circuit trace. The circuit die also includes an output signal circuit trace having first and second ends. The first end of the output signal circuit trace is coupled to the circuit output node. The circuit die also includes an output signal bonding pad coupled to the second end of the output signal circuit trace. The magnetic field sensor further includes a circuit loop. The circuit loop includes a conductive path between the ground pin and the signal output pin. The circuit loop has a circuit loop interior area. The magnetic field sensor further includes a compensated signal output node coupled to the circuit output node. The magnetic field sensor further includes a conductive structure, which includes a compensation loop coupled in a series arrangement with the circuit loop. The compensation loop has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop. A path traversing the circuit loop in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node resulting from the circuit loop experiencing a rapid change in flux of the magnetic field. 
     In some embodiments, the compensation loop is coupled between the circuit output node and the compensated signal output node or the compensation loop is coupled between the between a loop termination node and the ground node. 
     In accordance with another aspect of the present invention, in a magnetic field sensor having a lead frame having a ground pin and a signal output pin, the magnetic field sensor also comprising a circuit die disposed upon the lead frame and comprising a magnetic field sensing element and an output circuit coupled to the magnetic field sensing element, wherein the output circuit comprises a circuit ground node and a circuit output node, a method of compensating an output signal in the magnetic field sensor responsive to a magnetic field includes identifying a circuit loop in the magnetic field sensor. The circuit loop includes a conductive path between the ground pin and the signal output pin. The circuit loop has a circuit loop interior area. The method also includes providing a compensated signal output node coupled to the circuit output node. The method also includes providing a conductive structure. The providing the conductive structure includes providing a compensation loop coupled in a series arrangement with the circuit loop. The compensation loop has a compensation loop interior area selected to be related to the interior area of the circuit loop. A path traversing the circuit loop in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node resulting from the circuit loop experiencing a rapid change in flux of the magnetic field. 
     In some embodiments, providing the compensation loop comprises providing the compensation loop coupled between the circuit output node and the compensated signal output node or providing the compensation loop coupled between the between a loop termination node and the ground node. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a pictorial showing a current sensor having a U-shaped flux concentrator; 
         FIGS. 2 and 2A  are block diagrams showing two views of another embodiment of a current sensor having a donut shaped flux concentrator; 
         FIG. 3  is a graph showing a magnetic field of the current sensors of  FIG. 1 ,  2  or  2 A along an x direction; 
         FIG. 3A  is a graph showing a magnetic field of the current sensors of  FIG. 1 ,  2 , or  2 A along a y direction; 
         FIG. 4  is a block diagram of circuitry that can be included in the current sensors of  FIG. 1 ,  2 , or  2 A, the block diagram showing a so-called circuit loop and showing a so-called compensation loop; 
         FIGS. 4A-4C  are pictorial diagrams showing two loops, looping in opposite directions, coupled in a variety of series arrangements; 
         FIG. 5  is block diagram showing a circuit loop occurring in a prior art magnetic field sensor, here in a current sensor; 
         FIG. 6  is a graph showing a rapidly changing current sensed by the prior art current sensor of  FIG. 5 ; 
         FIG. 6A  is a graph showing a rapidly changing output signal generated by the prior art current sensor of  FIG. 5  when experiencing the rapidly changing current of  FIG. 6 , showing an unwanted transient signal portion; 
         FIG. 6B  is a graph showing a rapidly changing current sensed by a current sensor of the present invention; 
         FIG. 6C  is a graph showing a rapidly changing output signal generated by the current sensor of the present invention when experiencing the rapidly changing current of  FIG. 6B , showing no unwanted transient signal portion or a reduced amplitude transient signal portion; 
         FIG. 7  is block diagram showing a circuit die having a compensation loop on a signal side of an output amplifier; 
         FIG. 7A  is block diagram showing a circuit die having a compensation loop on a ground side of an output amplifier; 
         FIG. 8  is a block diagram showing the circuit die of  FIG. 7  coupled to a lead frame in an integrated circuit package; 
         FIG. 8A  is a block diagram showing the circuit die of  FIG. 7A  coupled to a lead frame in an integrated circuit package; 
         FIG. 9  is a block diagram showing a circuit die, for example, the circuit die of  FIG. 5 , coupled to a lead frame in an integrated circuit package, wherein the lead frame includes a compensation loop on a signal side of an output amplifier; 
         FIG. 9A  is a block diagram showing a circuit die, for example, the circuit die of  FIG. 5 , coupled to another lead frame in an integrated circuit package, wherein the lead frame includes a compensation loop on a signal side of an output amplifier; 
         FIG. 9B  is a block diagram showing a circuit die, for example, the circuit die of  FIG. 5 , coupled to yet another lead frame in an integrated circuit package, wherein the lead frame includes a compensation loop on a ground side of an output amplifier; 
         FIG. 10  is a block diagram showing a circuit die, for example, the circuit die of  FIG. 5 , coupled to yet another lead frame in an integrated circuit package, wherein the integrated circuit package is coupled to a circuit board, wherein the circuit board includes a compensation loop on the signal side of an output amplifier; 
         FIG. 10A  is a block diagram showing a circuit die, for example, the circuit die of  FIG. 5 , coupled to yet another lead frame in an integrated circuit package, wherein the integrated circuit package is coupled to a circuit board, wherein the circuit board includes a compensation loop on the ground side of an output amplifier; 
         FIGS. 11 and 11A  are block diagrams showing two views of a circuit die coupled to yet another lead frame in an integrated circuit package, wherein the lead frame includes a compensation loop on a signal side of an output amplifier, and wherein the compensation loop has bends to transition to a plane below a base plate of the lead frame; 
         FIGS. 12 and 12A  are block diagrams showing two views of a circuit die coupled to yet another lead frame in an integrated circuit package, wherein the integrated circuit includes a circuit board having a compensation loop on a signal side of an output amplifier; 
         FIG. 13  is a side view of a circuit die coupled to a lead frame with a direct bonding method, coupled with solder balls or the like; and 
         FIG. 13A  is a side view of a circuit die coupled to a lead frame with a direct bonding method in a relative flip-chip arrangement, coupled with solder balls or the like. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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). 
     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, most types of magnetoresistance elements tend to have axes of maximum sensitivity parallel to the substrate and most types of Hall elements tend to have axes of sensitivity perpendicular to a substrate. 
     As used herein, the term “magnetic field sensor” is used to describe a circuit that includes a magnetic field sensing element. Magnetic field sensors are used in a variety of applications, including, but not limited to, 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. 
     While magnetic field sensors having Hall effect elements are shown and described in examples below, the same techniques can be applied to a magnetic field sensor having any type of magnetic field sensing element. 
     Current sensors are shown and described in examples, below. However, the same techniques can be applied to any magnetic field sensor, and, desirably, to any magnetic field sensor that experiences a rapid rate of change in a magnetic field. 
     Current sensors with flux concentrators are shown and described in examples below. It will be understood that the use of a flux concentrator tends to increase the rate of change of a magnetic field experienced by the magnetic field sensor. While this increase tends to result in large output signal transients described below, for example, in conjunction with  FIGS. 6 and 6A , techniques described below can be applied to any magnetic field sensor, with or without a flux concentrator. 
     Referring to  FIG. 1 , an integrated current sensor  10 , shown in an exploded view prior to final assembly, includes a magnetic field sensing element, here in the form of Hall effect magnetic sensor  12  (here shown without an encapsulated body for clarity), a current-carrying conductor  16  and a magnetic core  24 . The conductor  16  includes features for receiving portions of the Hall effect sensor  12  and the magnetic core  24  such that the elements are maintained in a fixed and aligned position relative to each other. 
     In the illustrated embodiment, the conductor  16  has a first notch  18   a  and a second notch  18   b  substantially aligned with the first notch. When assembled, at least a portion of the Hall effect sensor  12  is disposed in the first notch  18   a . The magnetic core  24  is substantially C-shaped (or U-shaped) and has a central region  24   a  and a pair of substantially parallel legs  24   b ,  24   c  extending from the central region. When assembled, at least a portion of the central region  24   a  is disposed in the second notch  18   b  of the conductor  16  such that each leg  24   b ,  24   c  covers at least a portion of a respective surface of the Hall effect sensor  12 . 
     In some embodiments, the conductor  16 , and, in particular, the notches  18   a ,  18   b , are formed by stamping. 
     The Hall effect sensor  12  is provided in the form of an integrated circuit containing a sensor die  14  having a Hall effect element  14   a  thereon, all encapsulated with an electrically insulating material. The integrated Hall effect sensor  12  can be provided in different package types, such as the “K” single in line (SIP) package having a thickness on the order of 1.6 mm. The effective air gap is equal to the thickness of the package, with the sensor die resting approximately in the center of the air gap. 
     The Hall effect sensor has leads  15  adapted for mounting to a printed circuit board (not shown). Leads  15  include a power, or Vcc, connection, a ground connection, and an output connection adapted to carry an output signal proportional to the current through the conductor  16 . The output signal can be a current or a voltage. 
     The sensor die  14  includes the Hall effect element  14   a  and Hall circuitry  14   b  for processing the output signal of the Hall effect element  14   a . Use of the Hall effect sensor  12  enhances the integration of the current sensor  10  by incorporating circuit components which otherwise would be provided separately, such as by discrete components mounted to a printed circuit board. 
     The conductor  16  can be comprised of various conductive materials, such as copper, and is adapted for mounting to a printed circuit board through which the measured current is provided to the conductor  16 . To this end, bent leads or tabs  16   a ,  16   b  ( 16   b  not shown) suitable for soldering into circuit board vias (or holes) are provided at end portions of the conductor  16 . Mechanisms other than bent tabs  16   a ,  16   b  may be used to mount the current sensor  10  to a circuit board, such as screw terminals and associated hardware or flat leads or tabs. In alternate embodiments, the same or other mounting mechanisms can be used to allow the current sensor  10  to be mounted to other than a circuit board. For example, the current sensor  10  can have wire couplings (not shown) that allow the current sensor  10  to be coupled in series with a wire. 
     Preferably, the conductor  16  (excluding the bent tabs  16   a ,  16   b ) is substantially planar as shown, without features extending in the z-axis  21  which would increase the height of the current sensor  10  off of the printed circuit board. In use, the plane of the conductor  16  is positioned close to the printed circuit board plane, thereby providing a low profile current sensor. 
     The first notch  18   a  of the conductor  16  has a width w 2  selected to receive at least a portion of the Hall effect sensor  12 , which has a width w 1 . Preferably, the width w 1  and the width w 2  are sufficiently similar so that, in assembly, the possible movement of the Hall effect sensor  12  relative to the conductor  16  in the x-axis  19  is negligible. More specifically, nominal width w 1  is slightly smaller than nominal width w 2 , such as by approximately 0.28 mm, so that, with worst case tolerances, the largest width w 1  is 0.4 mm smaller than the smallest width w 2 . In the illustrated embodiment, nominal width w 1  is 5.18 mm and nominal width w 2  is 5.46 mm. Widths w 1  and w 2  can thus be characterized as being substantially equal. 
     The second notch  18   b  of the conductor has a width w 3  selected to receive at least a portion of the magnetic core  24 . Preferably, the width w 3  and the width w 4  of the central region  24   a  of the magnetic core are sufficiently similar, so that, in assembly, the possible movement of the magnetic core  24  relative to the conductor  16  in the x-axis  19  is negligible. More specifically, nominal width w 4  is slightly smaller than nominal width w 3 , such as by approximately 0.2 mm, so that, with worst case tolerances, the smallest width w 4  is 0.34 mm smaller than the largest width w 3  and the largest width w 4  is 0.08 mm smaller than the smallest width w 3 . In the illustrated embodiment, nominal width w 3  is 5.46 mm and nominal width w 4  is 5.25 mm. Widths w 3  and w 4  can thus be characterized as being substantially equal. 
     The spacing h 3  between magnetic core legs  24   b ,  24   c , the thickness or height h 2  of the conductor  16  and the thickness or height h 1  of the Hall effect sensor  12  are all substantially similar so that possible movement of the components relative to each other in the z-axis  21  is restricted. More specifically, nominal conductor height h 2  and sensor height h 1  are slightly smaller than nominal height h 3 , such as by approximately 0.1 mm, so that, with worst case tolerances, the smallest height h 1  and height h 2  are 0.22 mm smaller than the largest height h 3  and the largest height h 1  and height h 2  are 0.01 mm smaller than the smallest height h 3 . In the illustrated embodiment, the nominal height h 1  is 1.55 mm, the nominal height h 2  is 1.50 mm, and the nominal height h 3  is 1.64 mm. 
     In other embodiments, however, the spacing h 3  is selected in accordance with other factors. For example, in one alternate embodiment, the spacing h 3  is substantially larger than the height h 1  of the Hall effect sensor  12 , in order to increase the reluctance and, therefore, to increase the current through the carrying conductor  16  that would saturate the current sensor  10 . Thus, this alternate embodiment has a greater current carrying capacity. 
     The magnetic core  24  tailors the magnetic field across the sensor die  14  and may be referred to alternatively as a magnetic field concentrator, a magnetic flux concentrator, or simply as a flux concentrator. The magnetic core  24  may be comprised of various materials including, but not limited to ferrite, steel, iron compounds, and permalloy. The material of the magnetic core  24  is selected based on factors such as maximum measured current, which is related to a magnetic permeability of the core  24 , and the desired amount of magnetic shielding provided by the magnetic core  24 . Other factors include stability of the relative permeability over temperature and hysteresis (magnetic remanence). For example, a low hysteresis ensures greater accuracy for small currents through the conductor  16 . The material and size of the magnetic core  24  are also selected in accordance with the desired full scale current through the conductor  16 , wherein a magnetic core material with a higher saturation flux density (Bsat) allows the use of a smaller core for a given current flowing through the conductor  16 . As will become apparent from consideration of  FIG. 4  below, use of the magnetic core  24  significantly reduces the susceptibility of the current sensor  10  to stray magnetic fields. 
     The magnetic core  24  has a depth d 1 , selected so that each of the legs  24   b ,  24   c  substantially covers an entire respective surface of the sensor die  14 . With this arrangement, a substantially uniform magnetic field is provided across the Hall effect element  14   a  disposed on the sensor die  14 , thereby increasing device sensitivity and reducing susceptibility to stray magnetic fields. 
     Here, the conductor notch  18   a  is formed by tabs  16   d ,  16   e  extending radially outward from the conductor. Notch  18   b  is formed by a narrowed region  16   c  of the conductor in combination with tabs  16   f ,  16   g  extending from the conductor. The width w 5  of the narrowed region  16   c  between the first and the second notches  18   a ,  18   b  is selected based on the maximum current carrying capability of the electrical conductor  16 . In some embodiments, the width w 5  is on the order 1.7 mm and the current carrying capability of the conductor  16  is on the order of 100 Amperes. Although the notches  18   a ,  18   b  could be formed by radial tabs  16   d ,  16   e , and  16   f ,  16   g  respectively, without providing the narrowed conductor region  16   c , the use of the narrowed region  16   c  minimizes the overall dimension of the current sensor  10  along the y-axis  20 . The narrowed region also provides the current through the conductor  16  in closer proximity to the Hall effect sensor  12 . In an alternate embodiment, the notches  18   a ,  18   b  are formed without the tabs  16   d - 16   g , and are provided only by the narrowed region  16   c.    
     It will be understood that the current carrying conductor  16 , when passing a current, will cause a relatively large magnetic field at the Hall effect element  14   a , larger than if the flux concentrator  24  were not used. Furthermore, it will become apparent from discussion below in conjunction with  FIGS. 3 and 3A  that the magnetic field at the Hall effect element  14   a  will be relatively uniform over a large area in x and y directions  19 ,  20 , respectively, more uniform than if the flux concentrator  24  were not used. 
     Referring now to  FIGS. 2 and 2A , another embodiment  50  of a current sensor  50  includes a donut shaped flux concentrator  52  having a notch or cutout  56  therein and a central hole  54 . A magnetic field sensor  58  having a Hall effect element  58   a  and leads  60  can be disposed in the notch  56 . 
     It will be understood that a current carrying conductor (not shown) positioned to pass through the hole  54 , when passing a current, will cause a relatively large magnetic field at the Hall effect element  58   a , larger than if the flux concentrator  52  were not used. Furthermore, it will become apparent from discussion below in conjunction with  FIGS. 3 and 3A  that the magnetic field at the Hall effect element  58   a  will be relatively uniform over a large area in x and y directions  62 ,  64 , respectively, more uniform than if the flux concentrator  52  were not used, 
     Referring to  FIG. 3 , a graph  80  illustrates the magnetic flux density along the x-axis  19  of the Hall effect element  14   a  of  FIG. 1  or along the x-axis  62  of the Hall effect element  58   a  of  FIGS. 2 and 2A  when about one hundred Amperes is passed through the conductor  16  of  FIG. 1  or through the conductor (not shown) passing through the hole  56  of  FIGS. 2 and 2A . A center of the Hall effect element  14   a  ( FIG. 1 ) or a center of the Hall effect element  58   a  ( FIGS. 2 ,  2 A) corresponds to zero millimeters on the x-axes  19 ,  62 . 
     A magnetic flux curve  86  can be characterized as having a central portion  88  that is essentially flat and inclined end portions  90   a ,  90   b . Consideration of the curve  86  reveals that the magnetic flux is substantially constant in the central portion  88  for a span on the order of 4 mm centered about the centers of the Hall effect elements  14   a ,  58   a . Portions of the Hall effect elements  14   a ,  58   a  located more than 2 mm from their centers along the x-axes  19 ,  62  experience reduced magnetic flux density. The illustrative Hall effect elements  14   a ,  58   a  have an x-axis width on the order of 0.2 mm, centered on sensor die typically having dimensions of approximately 1.6 mm by 3 mm, and therefore, the entire Hall effect elements  14   a ,  58   a  lie in the central portion  88 . The width of the central portion  88  is substantially greater than the width of the Hall effect elements  14   a ,  58   a , and the Hall effect elements  14   a ,  58   a  are sufficiently centered within the central portion  88  to ensure that the Hall effect elements  14   a ,  58   a  are within the greatest amount of magnetic field. 
     It will be appreciated that the dimensions of the magnetic cores  24 ,  52  relative to the Hall effect elements  14   a ,  58   a  affect the uniformity of the flux density across the Hall effect elements  14   a ,  58   a  in the direction of the x-axes  19 ,  62 . In particular, the wider the magnetic core  24  (i.e., the greater the width w 4 ), relative to the width of the Hall effect element  14   a  in the x direction  19 , and the thicker the flux concentrator  52  in the x direction  62  relative to a width of the Hall effect element  58   a  in the x direction  62 , the longer the central portion  88  of the curve  86 , whereas, the narrower the magnetic core, the shorter the central portion  88 . 
     Curve  86  presumes that the magnetic cores  24 ,  52  and Hall effect elements  14   a ,  58   a  are centered relative to one another in the x directions  19 ,  62 , respectively. Movement of the Hall effect elements  14   a ,  58   a  relative to the magnetic cores  24 ,  52  along the x-axes  19 ,  62  would result in the curve  86  moving along the axis  84  and thus, result in areas of the Hall effect elements  14   a ,  58   a  even closer to their centers than 2 mm, experiencing significantly reduced flux density. This effect highlights the desirability of restricting relative movement of the Hall effect sensors  12 ,  58  and the magnetic cores  24 ,  52 . Further, since there is a tolerance associated with the location of the Hall effect elements  14   a ,  58   a  within the Hall effect sensors  12 ,  58 , respectively, fixing the position of the Hall effect sensors  12 ,  58  relative to the magnetic cores  24 ,  52  is important 
     Referring now to  FIG. 3A , a graph  100  illustrates the magnetic flux density along the y-axes  20 ,  64  of the Hall effect elements  14   a ,  58   a  when about one hundred Amperes is passed through the conductor  16  of  FIG. 1  or through the conductor (not shown) passing through the hole  54  of  FIGS. 2 and 2A . A center of the Hall effect elements  14   a ,  58   a  corresponds to zero millimeters on the axis  104 . 
     A magnetic flux curve  106  can be characterized as having a central portion  108  that is essentially flat and inclined end portions  110   a ,  110   b . Consideration of the curve  106  reveals that the magnetic flux is substantially constant in the central portion  108  for a span on the order of 2.5 mm centered about the center the all effect elements  14   a ,  58   a . Portions of the Hall effect elements  14   a ,  58   a  located more than 1.25 mm from their centers along the y-axes  20 ,  64  experience reduced magnetic flux density. The illustrative Hall effect elements  14   a ,  58   a  have a y-axis width on the order of 0.2 mm, centered on sensor die typically having dimensions of approximately 1.6 mm by 3 mm, and therefore the entire Hall effect elements  14   a ,  58   a  lie in the central portion  108 . The width of central portion  108  is substantially greater than the width of the Hall effect element  14   a ,  58   a , and the Hall effect elements  14   a ,  58   a  are sufficiently centered within the central portion  108  to ensure that the Hall effect elements  14   a ,  58   a  are within the greatest amount of magnetic field. 
     It will be appreciated that the dimensions of the magnetic cores  24 ,  52  relative to the Hall effect elements  14   a ,  58   a  significantly affect the uniformity of the flux density across the Hall effect elements  14   a ,  58   a  in the direction of the y-axes  20 ,  64 . In particular, the deeper the magnetic cores  24 ,  52  in the y directions  20 ,  64 , relative to the width of the Hall effect elements  14   a ,  58   a , the longer the central portion  108  of the curve  106 , whereas, the shallower the magnetic core, the shorter the central portion  108 . 
     Curve  106  presumes that the magnetic cores  24 ,  52  and Hall effect elements  14 ,  58   a  are centered relative to one another in the y directions  20 ,  64 . Movement of the Hall effect elements  14   a ,  58   a  relative to the magnetic cores  24 ,  52  along the y-axes  20 ,  64  would result in the curve  106  moving along the axis  104  and thus, result in areas of the Hall effect elements  14   a ,  58   a , even closer to their centers than 1.25 mm, experiencing significantly reduced flux density. This effect again highlights the desirability of restricting relative movement of the Hall effect sensor  12 ,  58  relative to the magnetic cores  24 ,  52 . 
     Referring now to  FIG. 4 , in which like elements of  FIG. 1  are shown having like reference designations, a schematic representation of the exemplary Hall effect current sensor  10  of  FIG. 1  includes the conductor  16  represented by a line having circuit board mounting mechanisms  16   a ,  16   b , and the magnetic core  24  here represented by a toroid  162 . While the representation of  FIG. 4  is described in conjunction with  FIG. 1 , it will be understood that the same description and circuits can apply to the magnetic field sensor  50  of  FIGS. 2-2A . The illustrative Hall effect sensor  12  includes the sensor die  14  and leads  15 , here labeled  15   a ,  15   b , and  15   c . Lead  15   a  provides a power connection to the Hall effect current sensor  12 , lead  15   b  provides a connection to the current sensor output signal, and lead  15   c  provides a reference, or ground connection to the current sensor. 
     The Hall effect element  14   a  senses a magnetic field  164  induced by a current flowing in the conductor  16 , producing a voltage in proportion to the magnetic field  164 . The Hall effect element  14   a  is coupled to a dynamic offset cancellation circuit  170 , which provides a DC offset adjustment for DC voltage errors associated with the Hall effect element  14   a . When the current through the conductor  16  is zero, the output of the dynamic offset cancellation circuit  170  is adjusted to be zero. 
     The dynamic offset cancellation circuit  170  is coupled to an amplifier  172  that amplifies the offset adjusted Hall output signal. The amplifier  172  is coupled to a filter  174  that can be a low pass filter, a high pass filter, a band pass filter, and/or a notch filter. The filter is selected in accordance with a variety of factors including, but not limited to, desired response time, the frequency spectrum of the noise associated with the Hall effect element  14   a , the dynamic offset cancellation circuit  170 , and the amplifier  172 . In one particular embodiment, the filter  174  is a low pass filter. The filter  174  is coupled to an output driver  176  that provides an enhanced power output for transmission to other electronics (not shown). 
     A trim control circuit  184  is coupled to lead  15   a  through which power is provided during operation. Lead  15   a  also permits various current sensor parameters to be trimmed, typically during manufacture. To this end, the trim control circuit  184  includes one or more counters enabled by an appropriate signal applied to the lead  15   a.    
     The trim control circuit  184  is coupled to a quiescent output voltage (Qvo) circuit  182 . The quiescent output voltage is the voltage at output lead  15   b  when the current through conductor  16  is zero. Nominally, for a unipolar supply voltage, Qvo is equal to Vcc/2. Qvo can be trimmed by applying a suitable trim signal through the lead  15   a  to a first trim control circuit counter within the trim control circuit  184  which, in turn, controls a digital-to-analog converter (DAC) within the Qvo circuit  182 . 
     The trim control circuit  184  is further coupled to a sensitivity adjustment circuit  178 . The sensitivity adjustment circuit  178  permits adjustment of the gain of the amplifier  172  in order to adjust the sensitivity of the current sensor  10 . The sensitivity can be trimmed by applying a suitable trim signal through the lead  15   a  to a second trim control circuit counter within the trim control circuit  184  which, in turn, controls a DAC within the sensitivity adjustment circuit  178 . 
     The trim control circuit  184  is further coupled to a sensitivity temperature compensation circuit  180 . The sensitivity temperature compensation circuit  180  permits adjustment of the gain of the amplifier  172  in order to compensate for gain variations due to temperature. The sensitivity temperature compensation can be trimmed by applying a suitable trim signal through the lead  15   a  to a third trim control circuit counter within the trim control circuit  184  which, in turn, controls a DAC within the sensitivity temperature compensation circuit  180 . 
     An output signal from the output driver  176  experiences two conductive loops in conjunction with its path from the output driver to the signal output pin  15   b . A first loop  190 , referred to herein as a “circuit loop,” has a first rotation direction indicated by an arrow, and a second loop  192 , referred to herein as a “compensation loop,” has a second different and opposite rotation direction indicated by another arrow. The circuit loop  190  is described more fully below in conjunction with  FIG. 5 . The compensation loop is described more fully below in conjunction with  FIGS. 7-12B . 
     Let it suffice here to say that the circuit loop  190  is naturally occurring in the sensor die  14  due to layout of circuits on the circuit die  14 . The circuit loop  190  tends to generate a transient signal when the circuit loop directly experiences a rapid change of magnetic field as may be generated by a rapid change of current passing through the conductor  16 . The compensation loop  192  is a physical conductive loop having a variety of configurations that can be provided to cancel or reduce the transient signal that forms as a result of the circuit loop  190 . 
     It will be appreciated that the circuitry shown in  FIG. 4  is illustrative only of exemplary circuitry that may be associated with and integrated into a Hall effect current sensor, like the Hall effect current sensor  10  of  FIG. 1 . In another embodiment, additional circuitry may be provided for converting the current sensor into a “digital fuse” which provides a high or low output signal depending on whether the magnetic field  164  induced by the current through the conductor  16  is greater or less than a predetermined threshold level. The additional circuitry for this alternative embodiment can include a comparator and/or a latch, and/or a relay. An exemplary embodiment of a digital fuse is shown in  FIG. 7 . 
     Further, since the conductor connections  16   a ,  16   b  are electrically isolated from the current sensor leads  15   a ,  15   b , and  15   c , the current sensor  10  can be used in applications requiring electrical isolation without the use of opto-isolators or other isolating techniques, such as transformers. 
     Referring now to  FIG. 4A , the two loops  190 ,  192  of  FIG. 4  are again shown but with better clarity. The two loops are coupled in a series arrangement, a path from left to right rotating counterclockwise in the first loop and the path rotating clockwise in the second loop. Both of the loops are shown to be closed loops. 
     Referring now to  FIG. 4B , two different loops are shown and are again coupled in a series arrangement. The loops are open loops. As used herein, the term “loop” refers to both open loops and to closed loops, and more particularly, to any conductor that takes any curved path through any number of degrees, for example, bending through ninety degrees. 
     As in  FIG. 4B , a path from left to right rotates counterclockwise in the first loop and the path rotates clockwise in the second loop. 
     Referring now to  FIG. 4C , two different loops are again coupled in a series arrangement, a second loop intermediate to the first loop. 
     A path from left to right rotates counterclockwise in a first portion the first loop, the path rotates clockwise in the second loop, and the path rotates counterclockwise again in a second portion the first loop. It will, therefore, be understood that the term “series arrangement” when referring to a coupling of two loops can be a coupling of the loops, one after the other, or a coupling wherein a second loop is intermediate to the first loop. 
     While the path through the first loop is shown to rotate counterclockwise and the path through the second loop is shown to rotate clockwise, the reverse is also possible. Also, while rotations in different direction are shown, and such is the case in embodiments shown below as will be apparent, series connected loops can also have paths that rotate in the same direction. 
     In FIGS.  5  and  7 - 12 B below, magnetic field sensor are shown without flux concentrators for clarity. However, preferably, all of the magnetic field sensors of FIGS.  5  and  7 - 12 B include a respective flux concentrator, for example, a flux concentrator having the form of one of those shown in  FIGS. 1 ,  2 , and  2 A. 
     Referring now to  FIG. 5 , a magnetic field sensor  200  is shown without a flux concentrator. The magnetic field sensor  200  can include a circuit die  203  and a lead frame  240  disposed within a molded package  202 . The circuit die  203  can include a Hall effect element  204  configured to generate a magnetic field signal carried on a conductor  206 . The signal carried by the conductor  206  is responsive to a current  244  flowing through a conductor  242  disposed near to the Hall effect element  204 . Interface circuits  208  are coupled to receive the magnetic field signal carried by the conductor  206  and configured to generate an interface signal carried by a conductor  210 . An output amplifier (or buffer)  212  is coupled to receive the interface signal carried on the conductor  210 . The interface circuits  208  and the output amplifier  212  will be readily understood from the above discussion in conjunction with  FIG. 4 . 
     The output amplifier  212  includes a circuit ground node  216  and a circuit output node  218 . The circuit output node  218  is coupled to the circuit ground node  216  via an internal resistance  214  within the output amplifier  212 . 
     A ground circuit trace  228  has first and second ends, wherein the first end of the ground circuit trace  228  is coupled to the circuit ground node  216 . A ground bonding pad  220  is coupled to the second end of the ground circuit trace  228 . An output signal circuit trace  230  has first and second ends, wherein the first end of the output signal circuit trace  230  is coupled to the circuit output node  218 . An output signal bonding pad  222  is coupled to the second end of the output signal circuit trace  230 . 
     A signal bond wire  232  is coupled between the output signal bonding pad  222  and a signal output pin  236 , which is part of the lead frame  240 . A ground bond wire  226  is coupled between the ground bonding pad  220  and a ground node  234  on a base plate  241 , which is part of the lead frame  240 , which is coupled to a ground pin  238 , which is part of the lead frame  240 . 
     The ground bond wire  226 , the ground circuit trace  228 , the resistance  214 , the output signal circuit trace  230 , and the output signal bond wire  232  form parts of a so-called “circuit loop”  234 , shown as a dashed line. The circuit loop  234  can be symbolically closed by way of a horizontal line shown at the lower perimeter of the molded package  202 . 
     It will be understood that a conductive loop tends to form a voltage at ends thereof in response to a rapidly changing magnetic field as may be generated by the current  244  when rapidly changing. The voltage tends to result in a transient and unwanted signal shown and described below in conjunction with  FIGS. 6 and 6A . 
     The generated voltage in a loop is described by Faraday&#39;s Law:
 
 V=−N ( dΦ/dt )
 
where:
         N is the number of turns of a loop   Φ is magnetic flux; and   dΦ/dt is a rate of change of magnetic flux.
 
It will be understood that:
   Φ=BA if B is uniform and perpendicular to a plan of the loop
 
where: B is flux density; and
   A is area of the loop. (Note that, for an open loop, the area can be found by connecting the ends of the loop with a line, for example, a straight line.)       

     Thus, the induced voltage in a loop is proportional to a rate of change of magnetic flux, related to a number of turns of the loop, and related to an area of the loop. 
     As shown, the circuit loop  234  is bounded within a rectangle that is about 3 mm×about 1.5 mm. The circuit loop, which does not fill the entire rectangular area, has a circuit loop interior area that is about 3.6 square millimeters. A path traversing the circuit loop  234  in a direction from the ground pin  238  to the signal output pin  236  has a circuit loop rotation direction, which can be counterclockwise as shown, or which can be clockwise in other arrangements. 
     It will be understood that the boundaries of the circuit loop, found by inspection of an irregular shape, may not be entirely correct. Thus, there may be one or more trial and error circuit die fabrication attempts to establish the area of the circuit loop. 
     Referring now to  FIG. 6 , a graph  250  has a horizontal axis in units of time in microseconds and a vertical axis in units of electrical current in Amperes. A signal  252  has a transition region representative of a rapidly changing current as may be carried by the conductor  242  of  FIG. 5 . 
     Referring now to  FIG. 6A , a graph  260  has a horizontal axis in units of time in microseconds and a vertical axis in units of voltage in volts. In response to the current signal  252  of  FIG. 6 , a signal  262  is representative of an output signal as may be generated at the output signal pin  236  of  FIG. 5 . The signal  262  has an unwanted transient signal portion  264 , not representative of the current signal  252  of  FIG. 6 , shown as a downward transition coincident with the onset of the transition region of the signal  252  of  FIG. 6 . 
     It has been recognized by the invention herein that the transient signal portion  264  is generated by the circuit loop  234  of  FIG. 5  as it experiences a high rate of change of magnetic field (or a high rate of change of magnetic flux). In other words, the transient signal portion  264  is generated as a result of a physical conductive loop at or near the output amplifier of the magnetic field sensor  200  of  FIG. 5 . 
     As described above, others have attempted to remove the transient signal  264  by way of filters or the like. However, these techniques tend to slow down a response rate of the signal  262 . It has not been previously known that the transient signal is the result of the above-described circuit loop as it experiences a high rate of change of magnetic field. 
     Referring now to  FIG. 6B , the graph  250  of  FIG. 6  is again shown. 
     Referring now to  FIG. 6C , a graph  270  has a horizontal axis in units of time in microseconds and a vertical axis in units of voltage in volts. In response to the current signal  252  of  FIG. 6B , a signal  272  is representative of an output signal as may be generated at an output pin of circuits shown and described below, which include a compensation loop coupled in series with the circuit loop  234  of  FIG. 5 . The signal  262  has no transient signal portion like the transient signal portion  264  of  FIG. 6A . 
     Referring now to  FIG. 7 , a circuit die  300  can include a Hall effect element  302  configured to generate a magnetic field signal carried on a conductor  304 . Interface circuits  306  are coupled to receive the magnetic field signal carried by the conductor  304  and configured to generate an interface signal carried by a conductor  308 . An output amplifier (or buffer)  310  is coupled to receive the interface signal carried on the conductor  308 . 
     The output amplifier  310  includes a circuit ground node  314  and a circuit output node  316 . The circuit output node  316  is coupled to the circuit ground node  314  via an internal resistance  312  within the output amplifier  310 . 
     A ground circuit trace  322  has first and second ends, wherein the first end of the ground circuit trace  322  is coupled to the circuit ground node  314 . A ground bonding pad  318  is coupled to the second end of the ground circuit trace  322 . 
     An output signal circuit trace  324  has first and second ends, wherein the first end of the output signal circuit trace  324  is coupled to the circuit output node  316 . An output signal bonding pad  320  is coupled to the second end of the output signal circuit trace  324 . 
     The output signal circuit trace  324 , unlike the output signal circuit trace  230  of  FIG. 5 , takes a circular route in a “compensation loop” to reach the output signal bonding pad  320 . A direction of the compensation loop  324  from the circuit output node  318  to the output signal bonding pad  320  (here clockwise) takes a direction opposite to the above-described circuit loop  234  of  FIG. 5 . 
     It will be recognized that the compensation loop  324  is coupled in a series arrangement with a circuit loop (not shown), which is the same as or similar to the circuit loop  234  of  FIG. 5 . Preferably, the compensation loop  324  has an interior area about the same as the interior area of the circuit loop  234  of  FIG. 5 . 
     It will be recognized that the compensation loop  324  and the circuit loop  234  of  FIG. 5  have opposite rotation directions and tend to respond with transient signals having opposite directions when the compensation loop  324  and the circuit loop  234  experience a large rate of change of magnetic field. Furthermore, if the compensation loop  324  and the circuit loop  234  both have about the same interior area and if the compensation loop  324  and the circuit loop  234  both experience about the same rapidly changing magnetic field, then the compensation loop  324  will tend to reduce or cancel the transient signal generated in the circuit loop  234 . 
     Particularly when using a flux concentrator proximate to the circuit die  300 , as will be apparent from the discussion above in conjunction with  FIGS. 3 and 3A , the compensation loop  324  will tend to experience the same magnetic field as the circuit loop  234 . However, even if the compensation loop  324  does not experience the same rapidly changing magnetic field as the circuit loop  234  of  FIG. 5 , an area of the compensation loop  324  or an area of the circuit loop  234  can be designed or adjusted accordingly to provide the cancellation or reduction results. 
     The circuit die  300  is shown in  FIG. 8  below when coupled into a magnetic field sensor, or more particularly, a current sensor. 
     Referring now to  FIG. 7A , in which like elements of  FIG. 7  are shown having like reference designations, a circuit die  350  can include the Hall effect element  302  configured to generate the magnetic field signal carried on the conductor  304 . The interface circuits  306  are coupled to receive the magnetic field signal carried by the conductor  304  and configured to generate the interface signal carried by the conductor  308 . The output amplifier (or buffer)  310  is coupled to receive the interface signal carried on the conductor  308 . 
     The output amplifier  310  includes the circuit ground node  314  and the circuit output node  316 . The circuit output node  316  is coupled to the circuit ground node  314  via the internal resistance  312  within the output amplifier  310 . 
     A ground circuit trace  352 , which is longer than the ground circuit trace  322  of  FIG. 7 , has first and second ends, wherein the first end of the ground circuit trace  352  is coupled to the circuit ground node  314 . A ground bonding pad  318  is coupled to the second end of the ground circuit trace  352 . 
     An output signal circuit trace  354 , which is shorter than the output signal circuit trace  324  of  FIG. 7 , has first and second ends, wherein the first end of the output signal circuit trace  354  is coupled to the circuit output node  316 . An output signal bonding pad  320  is coupled to the second end of the output signal circuit trace  354 . 
     The ground circuit trace  352 , unlike the ground circuit trace  228  of  FIG. 5 , takes a circular route in a “compensation loop” to reach the ground bonding pad  318 . A direction of the compensation loop  354  from the ground bonding pad  318  to the circuit ground node  314  (here clockwise) takes a direction opposite to the above-described circuit loop  234  of  FIG. 5 . 
     It will be recognized that the compensation loop  352  is coupled in a series arrangement with a circuit loop (not shown), which is the same as or similar to the circuit loop  234  of  FIG. 5 . Preferably, the compensation loop  352  has an interior area about the same as the interior area of the circuit loop  234  of  FIG. 5 . 
     It will be recognized that the compensation loop  352  and the circuit loop  234  of  FIG. 5  have opposite rotation directions and tend to respond with transient signals having opposite directions when the compensation loop  352  and the circuit loop  234  experience a large rate of change of magnetic field. Furthermore, if the compensation loop  352  and the circuit loop  234  both have about the same interior area and if the compensation loop  352  and the circuit loop  234  both experience about the same rapidly changing magnetic field, then the compensation loop  352  will tend to reduce or cancel the transient signal generated in the circuit loop  234 . 
     Particularly when using a flux concentrator proximate to the circuit die  350 , as will be apparent from the discussion above in conjunction with  FIGS. 3 and 3A , the compensation loop  352  will tend to experience the same magnetic field as the circuit loop  234 . However, even if the compensation loop  352  does not experience the same rapidly changing magnetic field as the circuit loop  234  of  FIG. 5 , an area of the compensation loop  352  or an area of the circuit loop  234  can be designed or adjusted accordingly to provide the cancellation or reduction results. 
     The circuit die  350  is shown in  FIG. 8A  below when coupled into a magnetic field sensor, or more particularly, a current sensor. 
     Referring now to  FIG. 8 , in which like elements of  FIG. 7  are shown having like reference designations, the circuit die  300  of  FIG. 7  is within a magnetic field sensor  400 . 
     The magnetic field sensor  400  includes a lead frame  420  having a base plate  418 , a ground pin  416  coupled to the base plate  420 , and a signal output pin  414 . The magnetic field sensor  400  includes the circuit die  300  of  FIG. 7  disposed upon the base plate  418 . The circuit die  300  includes a substrate  301 . The circuit die  300  also includes the magnetic field sensing element  302  disposed upon the substrate  301  and configured to generate a magnetic field signal responsive to a magnetic field (e.g., a magnetic field generated by a current  404  flowing in a conductor  402 ). The circuit die  301  also includes the output circuit  310  disposed upon the substrate  301 . The output circuit  310  includes the circuit ground node  314  and the circuit output node  316 . The output circuit  310  is configured to generate an output signal at the circuit output node  316  responsive to the magnetic field signal. The circuit die  301  also includes the ground circuit trace  322  having first and second ends. The first end of the ground circuit trace  322  is coupled to the circuit ground node  314 . The circuit die also includes the ground bonding pad  318  coupled to the second end of the ground circuit trace  322 . The circuit die  301  also includes the output signal circuit trace  324  having first and second ends. The first end of the output signal circuit trace  324  is coupled to the circuit output node  316 . The circuit die  301  also includes the output signal bonding pad  320  coupled to the second end of the output signal circuit trace  324 . The magnetic field sensor  400  further includes a circuit loop  234  ( FIG. 5 ). The circuit loop  234  includes a conductive path between the ground pin  416  and the signal output pin  414 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  400  further includes a compensated signal output node  412  coupled to the circuit output node  316 . The magnetic field sensor  400  further includes a conductive structure, which includes a compensation loop  324  coupled in a series arrangement with the circuit loop  234  ( FIG. 5 ). The compensation loop  324  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop  234 . Also, a path traversing (see, e.g., arrow  422 ) the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node  412  resulting from the circuit loop  234  experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 8 , the compensation loop  324  is coupled between the circuit output node  316  and the compensated signal output node  414 , i.e., on the signal side of the circuit loop  234 . The compensation loop  324  is the same as the signal circuit trace  324 . 
     Referring now to  FIG. 8A , in which like elements of  FIGS. 7A and 8  are shown having like reference designations, the circuit die  350  of  FIG. 7A  is within a magnetic field sensor  430 , i.e., on a signal side of the circuit loop  234 . 
     The magnetic field sensor  430  includes the lead frame  420  having the base plate  418 , the ground pin  416  coupled to the base plate  420 , and the signal output pin  414 . The magnetic field sensor  430  includes the circuit die  350  of  FIG. 7A  disposed upon the base plate  418 . The circuit die  350  includes a substrate  351 . The circuit die  350  also includes the magnetic field sensing element  302  disposed upon the substrate  351  and configured to generate a magnetic field signal responsive to a magnetic field (e.g., a magnetic field generated by the current  404  flowing in the conductor  402 ). The circuit die  351  also includes the output circuit  310  disposed upon the substrate  351 . The output circuit  310  includes the circuit ground node  314  and the circuit output node  316 . The output circuit  310  is configured to generate an output signal at the circuit output node  316  responsive to the magnetic field signal. The circuit die  351  also includes the ground circuit trace  352  having first and second ends. The first end of the ground circuit trace  352  is coupled to the circuit ground node  314 . The circuit die  351  also includes the ground bonding pad  318  coupled to the second end of the ground circuit trace  352 . The circuit die  351  also includes the output signal circuit trace  354  having first and second ends. The first end of the output signal circuit trace  354  is coupled to the circuit output node  316 . The circuit die also includes the output signal bonding pad  320  coupled to the second end of the output signal circuit trace  354 . The magnetic field sensor  430  further includes a circuit loop  234  ( FIG. 5 ). The circuit loop  234  includes a conductive path between the ground pin  416  and the signal output pin  414 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  430  further includes the compensated signal output node  412  coupled to the circuit output node  316 . The magnetic field sensor  430  further includes a conductive structure, which includes a compensation loop  352  coupled in a series arrangement with the circuit loop  234  ( FIG. 5 ). The compensation loop  352  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop  234  ( FIG. 5 ). Also, a path traversing (see, e.g., arrow  422 ) the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at a compensated signal output node  412  resulting from the circuit loop  234  experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 8A , the compensation loop  352  is coupled between a loop termination node  408  and the ground node  314 , i.e., on the ground side of the circuit loop  234 . The compensation loop  352  is the same as the ground circuit trace  352 . 
     Figures below present alternate structures that achieve the above-described compensation loops, some on a signal side of the circuit loop  234  of  FIG. 5 , and others on the ground side. 
     Referring now to  FIG. 9 , a magnetic field sensor  500  includes a lead frame  542  having a base plate  540 , a ground pin  538  coupled to the base plate  540 , and a signal output pin  536 . The magnetic field sensor  500  also includes a circuit die  508  disposed upon the base plate  540 . The circuit die  508  includes a substrate  509 . The circuit die  508  also includes a magnetic field sensing element  503  disposed upon the substrate  509  and configured to generate a magnetic field signal responsive to a magnetic field (e.g., a magnetic field generated by a current  504  flowing in a conductor  502 ). The circuit die  508  also includes an output circuit  510  disposed upon the substrate  508 . The output circuit  510  includes a circuit ground node  512  and a circuit output node  514 . The output circuit  510  is configured to generate an output signal at the circuit output node  514  responsive to the magnetic field signal. The circuit die  508  also includes a ground circuit trace  520  having first and second ends. The first end of the ground circuit trace  520  is coupled to the circuit ground node  512 . The circuit die  508  also includes a ground bonding pad  516  coupled to the second end of the ground circuit trace  520 . The circuit die  508  also includes an output signal circuit trace  522  having first and second ends. The first end of the output signal circuit trace  522  is coupled to the circuit output node  514 . The circuit die  508  also includes an output signal bonding pad  518  coupled to the second end of the output signal circuit trace  522 . The magnetic field sensor  500  further includes a circuit loop  234  ( FIG. 5 ). The circuit loop includes a conductive path between the ground pin  538  and the signal output pin  536 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  500  further includes a compensated signal output node  534  coupled to the circuit output node  514 . The magnetic field sensor  500  further includes a conductive structure, which includes a compensation loop  532  coupled in a series arrangement with the circuit loop  234 . The compensation loop  532  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop. Also, a path (see, e.g., arrow  544 ) traversing the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node  534  resulting from the circuit loop experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 9 , the compensation loop  532  is coupled between the circuit output node  514  and the compensated signal output node  534 , i.e., on the signal side of the circuit loop  234 . 
     The compensation loop  532  is formed from a portion of the lead frame  542 , and in particular, a loop  532  between the signal output pin  536  and a blind pin  530 . A bond wire  528  couples the signal output bonding pad  518  to the blind pin  530 . An insulator  546 , for example, Kapton tape, can be disposed between the compensation loop  532  and the circuit die  509 . 
     It will be understood that, in this embodiment, the substrate  509  hangs off of the base plate  540 , and therefore, is subject to breakage when the wire bond  528  is bonded. However, the output signal bonding pad  518  can be moved so as to be over the base plate  540  in order to reduce the chance of substrate breakage. 
     The magnetic field sensor is molded into a molded package  501 . In some arrangements, a double molding process can be used to support the substrate  509  during the wire bonding of the wire bond  528 . Double molding is further described below in conjunction with  FIGS. 11 and 11A . 
     Referring now to  FIG. 9A , in which like elements of  FIG. 9  are shown having like reference designations, a magnetic field sensor  550  includes a lead frame  566  having a base plate  564 , a ground pin  558  coupled to the base plate  564 , and a signal output pin  560 . The magnetic field sensor  550  also includes the circuit die  508  of  FIG. 9  disposed upon the base plate  540 . The circuit die  508  includes the substrate  509 . The circuit die  508  also includes the magnetic field sensing element  503  disposed upon the substrate  509  and configured to generate the magnetic field signal responsive to the magnetic field (e.g., the magnetic field generated by the current  504  flowing in the conductor  502 ). The circuit die  508  also includes the output circuit  510  disposed upon the substrate  508 . The output circuit  510  includes the circuit ground node  512  and the circuit output node  514 . The output circuit  510  is configured to generate the output signal at the circuit output node  514  responsive to the magnetic field signal. The circuit die  508  also includes the ground circuit trace  520  having first and second ends. The first end of the ground circuit trace  520  is coupled to the circuit ground node  512 . The circuit die  508  also includes the ground bonding pad  516  coupled to the second end of the ground circuit trace  520 . The circuit die  508  also includes the output signal circuit trace  522  having first and second ends. The first end of the output signal circuit trace  522  is coupled to the circuit output node  514 . The circuit die  508  also includes the output signal bonding pad  518  coupled to the second end of the output signal circuit trace  522 . The magnetic field sensor  550  further includes the circuit loop  234  ( FIG. 5 ). The circuit loop  234  includes a conductive path between the ground pin  558  and the signal output pin  560 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  550  further includes a compensated signal output node  562  coupled to the circuit output node  514 . The magnetic field sensor  550  further includes a conductive structure, which includes a compensation loop  556  coupled in a series arrangement with the circuit loop  234 . The compensation loop  556  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop  234 . Also, a path (see, e.g., arrow  572 ) traversing the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node  562  resulting from the circuit loop  234  experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 9A , the compensation loop  556  is coupled between the circuit output node  514  and the compensated signal output node  562 , i.e., on the signal side of the circuit loop  234  ( FIG. 5 ). 
     The compensation loop  556  is formed from a portion of the lead frame  566 , and in particular, a loop  556  between the signal output pin  560  and a blind pin  554 . A bond wire  552  couples the signal output bonding pad  518  to the blind pin  554 , and a bond wire  568  couples the ground bonding pad  516  to the base plate  564 . 
     Unlike the magnetic field sensor  500  of  FIG. 9 , the magnetic field sensor  550  has the ground pin  558  in the center of the pins, resulting in the compensation loop  556  avoiding the base plate  564  and avoiding the overhang of the substrate  509  as in  FIG. 9 . 
     Referring now to  FIG. 9B , in which like elements of  FIGS. 9 and 9A  are shown having like reference designations, a magnetic field sensor  600  includes a lead frame  620  having a base plate  618 , a ground pin  614  coupled to the base plate  618 , and a signal output pin  616 . The magnetic field sensor  600  also includes the circuit die  508  disposed upon the base plate  618 . The circuit die  508  includes the substrate  509 . The circuit die  508  also includes the magnetic field sensing element  503  disposed upon the substrate  509  and configured to generate the magnetic field signal responsive to the magnetic field (e.g., the magnetic field generated by the current  504  flowing in the conductor  502 ). The circuit die  508  also includes the output circuit  510  disposed upon the substrate  508 . The output circuit  510  includes the circuit ground node  512  and the circuit output node  514 . The output circuit  510  is configured to generate the output signal at the circuit output node  514  responsive to the magnetic field signal. The circuit die  508  also includes the ground circuit trace  520  having first and second ends. The first end of the ground circuit trace  520  is coupled to the circuit ground node  512 . The circuit die  508  also includes the ground bonding pad  516  coupled to the second end of the ground circuit trace  520 . The circuit die  508  also includes the output signal circuit trace  522  having first and second ends. The first end of the output signal circuit trace  522  is coupled to the circuit output node  514 . The circuit die  508  also includes the output signal bonding pad  518  coupled to the second end of the output signal circuit trace  522 . The magnetic field sensor  600  further includes the circuit loop  234  ( FIG. 5 ). The circuit loop  234  includes a conductive path between the ground pin  614  and the signal output pin  616 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  600  further includes a compensated signal output node  604  coupled to the circuit output node  514 . The magnetic field sensor  600  further includes a conductive structure, which includes a compensation loop  610  coupled in a series arrangement with the circuit loop  234 . The compensation loop  610  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop  234 . Also, a path (see, e.g., arrow  622 ) traversing the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node  604  resulting from the circuit loop  234  experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 9B , the compensation loop  610  is coupled between a loop termination node  608  and the ground node  512 , i.e., on the ground side of the circuit loop  234  ( FIG. 5 ). 
     The compensation loop  610  is formed from a portion of the lead frame  620 , and in particular, a loop  610  between the ground pin  614  and a blind pin  612 . A bond wire  602  couples the signal output bonding pad  518  to the signal output pin  616  and a bond wire  606  coupled the ground bonding pad  516  to the blind pin  612 . 
     Referring now to  FIG. 10 , in which like elements of  FIG. 9-9B  are shown having reference designations, a magnetic field sensor  674  includes an integrated magnetic field sensor  650  electrically coupled to a circuit board  675 . The integrated magnetic field sensor  650  is like the magnetic field sensors  500 ,  550 ,  600  of  FIGS. 9 ,  9 A,  9 B, respectively, but without any compensation loop. However, it will be understood that the integrated magnetic field sensor  650  includes the circuit loop  234  of  FIG. 5 . 
     The magnetic field sensor  674  (i.e., the integrated magnetic field sensor  650 ) includes a lead frame  672  having a base plate  670 , a ground pin  668  coupled to the base plate  670 , and a signal output pin  666 . The magnetic field sensor  674  also includes the circuit die  508  of  FIGS. 9-9B  disposed upon the base plate  670 . The circuit die  508  includes the substrate  509 . The circuit die  508  also includes the magnetic field sensing element  503  disposed upon the substrate  509  and configured to generate the magnetic field signal responsive to the magnetic field (e.g., a magnetic field generated by a current  654  flowing in a conductor  652 ). The circuit die  508  also includes the output circuit  510  disposed upon the substrate  508 . The output circuit  510  includes the circuit ground node  512  and the circuit output node  514 . The output circuit  510  is configured to generate the output signal at the circuit output node  514  responsive to the magnetic field signal. The circuit die  508  also includes the ground circuit trace  520  having first and second ends. The first end of the ground circuit trace  520  is coupled to the circuit ground node  512 . The circuit die  508  also includes the ground bonding pad  516  coupled to the second end of the ground circuit trace  520 . The circuit die  508  also includes the output signal circuit trace  522  having first and second ends. The first end of the output signal circuit trace  522  is coupled to the circuit output node  514 . The circuit die  508  also includes the output signal bonding pad  518  coupled to the second end of the output signal circuit trace  522 . The magnetic field sensor  674  further includes the circuit loop  234  ( FIG. 5 ). The circuit loop  234  includes a conductive path between the ground pin  668  and the signal output pin  666 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  674  further includes a compensated signal output node  658  coupled to the circuit output node  514 . The magnetic field sensor  674  further includes a conductive structure, which includes a compensation loop  656  coupled in a series arrangement with the circuit loop  234 . The compensation loop  656  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop  234 . Also, a path (see, e.g., arrow  676 ) traversing the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node  658  resulting from the circuit loop  234  experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 10 , the compensation loop  656  is coupled between the circuit output node  514  and the compensated signal output node  658 , i.e., on the signal side of the circuit loop  234  ( FIG. 5 ). 
     The compensation loop  656  is formed by a conductive trace upon the circuit board  675 , in one or more conductive layers of the circuit board  675 . A bond wire  664  couples the signal output bonding pad  518  to the signal output pin  666  and a bond wire  660  couples the ground bonding pad  516  to the base plate  670 . 
     The circuit board  675  can also include the conductor  652  as a current-carrying conductive trace configured to carry the current  654 , wherein the magnetic field is generated in response to the current. The compensation loop  656  is disposed proximate to the conductor  652 . The compensation loop  656  can be disposed at an edge of the conductor  652  so that the magnetic field passes perpendicularly through the compensation loop  656 . 
     The compensation loop  656  is shown here to include a plurality of nested loops. Particularly when the compensation loop  656  is not under the influence of a flux concentrator, which is shown in FIGS.  1  and  2 - 2 A, the compensation loop  656  will experience a smaller magnetic field than may be experienced by the circuit loop  234  ( FIG. 5 ). Thus, in order to compensate and reduce or cancel the transient signal of  FIG. 6A , it may be desirable to provide the compensation loop  656  with multiple loops as shown or with a larger area than the circuit loop  234  of  FIG. 5 . 
     Referring now to  FIG. 10A , in which like elements of  FIG. 9-9B  and  10  are shown having like reference designations, a magnetic field sensor  700  includes the integrated magnetic field sensor  650  of  FIG. 10 , electrically coupled to a circuit board  701 . The integrated magnetic field sensor  650  is like the magnetic field sensors  500 ,  550 ,  600  of  FIGS. 9 ,  9 A,  9 B, respectively, but without any compensation loop. However, it will be understood that the integrated magnetic field sensor  650  includes the circuit loop  234  of  FIG. 5 . 
     The magnetic field sensor  700  (i.e., the integrated magnetic field sensor  650 ) includes the lead frame  672  having the base plate  670 , the ground pin  668  coupled to the base plate  670 , and a signal output pin  666 . The magnetic field sensor  700  also includes the circuit die  508  of  FIGS. 9-9B  disposed upon the base plate  670 . The circuit die  508  includes the substrate  509 . The circuit die  508  also includes the magnetic field sensing element  503  disposed upon the substrate  509  and configured to generate the magnetic field signal responsive to the magnetic field (e.g., a magnetic field generated by a current  706  flowing in a conductor  704 ). The circuit die  508  also includes the output circuit  510  disposed upon the substrate  508 . The output circuit  510  includes the circuit ground node  512  and the circuit output node  514 . The output circuit  510  is configured to generate the output signal at the circuit output node  514  responsive to the magnetic field signal. The circuit die  508  also includes the ground circuit trace  520  having first and second ends. The first end of the ground circuit trace  520  is coupled to the circuit ground node  512 . The circuit die  508  also includes the ground bonding pad  516  coupled to the second end of the ground circuit trace  520 . The circuit die  508  also includes the output signal circuit trace  522  having first and second ends. The first end of the output signal circuit trace  522  is coupled to the circuit output node  514 . The circuit die  508  also includes the output signal bonding pad  518  coupled to the second end of the output signal circuit trace  522 . The magnetic field sensor  700  further includes the circuit loop  234  ( FIG. 5 ). The circuit loop  234  includes a conductive path between the ground pin  668  and the signal output pin  666 . The circuit loop  234  has a circuit loop interior area. The magnetic field sensor  700  further includes a compensated signal output node  667  coupled to the circuit output node  514 . The magnetic field sensor  700  further includes a conductive structure, which includes a compensation loop  702  coupled in a series arrangement with the circuit loop  234 . The compensation loop  702  has a compensation loop interior area. The compensation loop interior area is selected to be related to the interior area of the circuit loop  234 . Also, a path (see, e.g., arrow  710 ) traversing the circuit loop  234  in a direction from a first end of the series arrangement to a second end of the series arrangement has a circuit loop rotation direction opposite from a compensation loop rotation direction traversing the compensation loop along the same path. The compensation loop interior area and the compensation loop rotation direction are selected to result in a reduction of an overshoot or an undershoot of an output signal at the compensated signal output node  667  resulting from the circuit loop  234  experiencing a rapid change in flux of the magnetic field. 
     In the embodiment of  FIG. 10A , the compensation loop  702  is coupled between a loop termination node  708  and the ground node  512 , i.e., on the ground side of the circuit loop  234 . The loop termination node can be coupled to a reference voltage, for example, ground. 
     The compensation loop  702  is formed by a conductive trace upon the circuit board  701 , in one or more conductive layers of the circuit board  701 . The bond wire  664  couples the signal output bonding pad  518  to the signal output pin  666  and the bond wire  660  couples the ground bonding pad  516  to the base plate  670 . 
     The circuit board  674  can also include the conductor  704  as a current-carrying conductive trace configured to carry the current  706 , wherein the magnetic field is generated in response to the current  706 . The compensation loop  702  is disposed proximate to the conductor  704 . 
     The compensation loop  702  is shown here to include a plurality of nested loops. Particularly when the compensation loop  702  is not under the influence of a flux concentrator, which is shown in FIGS.  1  and  2 - 2 A, the compensation loop  702  will experience a smaller magnetic field than may be experienced by the circuit loop  234  ( FIG. 5 ). Thus, in order to compensate and reduce or cancel the transient signal of  FIG. 6A , it may be desirable to provide the compensation loop  702  with multiple loops as shown or with a larger area than the circuit loop  234  of  FIG. 5 . 
     Comparing  FIGS. 9 and 9A  above, it will be apparent that is may be difficult to provide a compensation loop formed as a part of a lead frame that does not interfere with the base plate of the lead frame.  FIGS. 11 and 11A  show another way for the compensation loop to avoid the base plate. 
     Referring now to  FIG. 11 , a magnetic field sensor  800  includes a lead frame  830  having a base plate  832 , a ground pin  828 , and a signal output pin  826 . The lead frame  830  also includes a compensation loop  820  coupled at one end to a blind pin  816  and at the other end to another blind pin  824 . Transition regions  818 ,  822  (or bends) can depress the compensation loop to be at a level below the base plate  832 . Though not shown as such, the depression could be used to pass the compensation loop  820  under the base plate  832 . 
     A ground bonding pad  812  is coupled to the base plate  832  with a bond wire  840 . A signal output bonding pad  814  is coupled to the blind pin  816  with a bond wire  834 . 
     The blind pin  824  is coupled to a bonding pad  804  upon circuit die  802  with a wire bond  838 . The bonding pad  804  is coupled with a circuit trace  808  to an opposite side of the circuit die  802 , to a bonding pad  806 . A bond wire  834  couples the bonding pad  806  to the signal output pin  826  and to a compensation node  844 . 
     The compensation loop  820  is shown to be coupled on an output signal side of a circuit loop  234  ( FIG. 5 ). However, it will be understood that a similar compensation loop can be coupled on a ground side of the circuit loop  234 . 
     Referring now to  FIG. 11A , in which like elements of  FIG. 11  are shown having like reference designations, the compensation loop  830  is shown to be in a different plane than the base plate  832  by way of the transition regions  818 ,  822 . A first molded body  840  can be first formed to support the compensation loop and the base plate. A second molded body  842  can be formed in a second molding step to surround the first molded body  840 , and the substrate  802 . 
     Referring now to  FIG. 12 , another magnetic field sensor  850  can include a lead frame  872  having a base plate  874 , a signal output pin  868 , and a ground pin  870  coupled to the base plate  874 . A small circuit board  858  can be disposed upon the base plate  874 . The circuit board  858  can include a compensation loop  860  formed as a conductive trace upon the circuit board  858 . A circuit die  852  can be disposed upon the circuit board  858 . The circuit die  852  can include a ground bonding pad  854  and a signal output bonding pad  856 . The signal output bonding pad  856  can be coupled to one end of the compensation loop  860  with a bond wire  861 . The other end of the compensation loop  860  can be coupled to the signal output pin  868  at a compensated signal output node  880  with a bond wire  866 . A bond wire  876  can couple the ground bonding pad  854  to the base plate  874 . 
     The compensation loop  860  is shown to be coupled on an output signal side of a circuit loop  234  ( FIG. 5 ). However, it will be understood that a similar compensation loop can be coupled on a ground side of the circuit loop  234 . 
     Referring now to  FIG. 12A , in which like elements of  FIG. 12  are shown having like reference designations, the magnetic field sensor  850  can include one molded body  851 . 
     Referring now to  FIG. 13 , whereas various circuit couplings to a signal output pin and to a ground pin are shown in prior figures to be comprised of wire bonds, in other embodiments, one or more of the circuit couplings to a signal output pin  920  and to a ground pin  924  of a lead frame  926  of any of the above-described magnetic field sensors can instead be direct couplings comprised of solder balls  908 ,  916 , coupled through soldering features  906 ,  914 , respectively, and through vias  904 ,  912 , respectively, to bonding pads  902 ,  910 , respectively, upon a substrate  900 . 
     In the arrangement shown, the active side of the substrate  900  is disposed upward such that an output amplifier  901  is disposed on a side of the substrate  900  that is facing away from the lead frame  926 . 
     While solder balls  908 ,  916  are shown, the direct bonding can be a selected one of a solder ball, a copper pillar, a gold bump, a eutectic and high lead solder bump, a no-lead solder bump, a gold stud bump, a polymeric conductive bump, an anisotropic conductive paste, or a conductive film coupled between the features  906 ,  914  and the lead frame pins. 
     Referring now to  FIG. 13A , direct couplings can instead be made between a substrate  950  and a lead frame  970  (e.g., to pins  964 ,  968 ) relatively disposed in a so-called “flip-chip” arrangement, such that an active surface of the substrate  950  is disposed downward such that an output amplifier  952  is disposed on a side of the substrate  950  that is facing toward the lead frame  970 . The direct couplings can be comprised of solder balls  956 ,  960 , coupled between bonding pads  954 ,  958 , respectively, and the lead frame pins  964 ,  968 . 
     While solder balls  956 ,  960  are shown, the direct bonding can be a selected one of a solder bail, a copper pillar, a gold bump, a eutectic and high lead solder bump, a no-lead solder bump, a gold stud bump, a polymeric conductive bump, an anisotropic conductive paste, or a conductive film coupled between the bonding pads  954 ,  958  and the lead frame pins. 
     While compensation loops are shown in embodiments above to be generally disposed on a signal side or on a ground side of the circuit loop  234  of  FIG. 5 , in other embodiments, the compensation loop can be placed in series arrangements at other intermediate regions of the circuit loop  234  (see, e.g.,  FIG. 4C ). 
     All references cited herein are hereby incorporated herein by reference in their entirety. 
     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.