Abstract:
An integrated sense resistor within an integrated circuit (IC) may be surroundingly positioned near and coupled to a connection such as a pin or ball. The integrated sense resistor may be shaped such that more surface area of the integrated sense resistor is coupled to be positioned closer or in actual contact with the pin or ball than conventional straight layered integrated sense resistor solutions. The integrated sense resistor may be a non-straight shape that entirely surrounds or wraps around a connection to the pin or ball, such as a circular or oval shape, a box or rectangular shape, a triangular shape, or a polygonal shape. The integrated sense resistor may be a non-straight shape that partially surrounds a connection to the pin or ball, such as an open-circular or semi-circular shape, an open-sided box or rectangular shape, an open-sided triangular shape, an angular shape, or an open curved shape.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/145,710 to Woodford et al. filed on Apr. 10, 2015 and entitled “Methods and Apparatuses for Surrounding Positioning and Coupling a Sense Resistor Near or Around a Chip Scale Package (CSP) Output Ball,” which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The instant disclosure relates to integrated circuits (ICs). More specifically, portions of this disclosure relate to sense resistors integrated with ICs and positioned near or around a chip scale package (CSP) output ball. 
       BACKGROUND 
       [0003]    A sense resistor is used to measure current for a circuit and can be included in or with an integrated circuit (IC). Sense resistors are useful for providing information about one component of an IC to other components of the IC. Some components of an IC may be less “intelligent” components, such as speakers, that have no capability to make decisions or execute logical statements. Other components of the IC may be more “intelligent” components, such as controllers or processors, that have logic circuity or general processing capability that can process decisions, generate control signals, and/or operate other components within the IC. A sense resistor is one monitoring tool that the more intelligent components may have access to when determining the condition or state of the less intelligent components. Design of the sense resistor is impacted by the IC&#39;s design, the IC&#39;s application, and/or the levels of currents that need to be measured or tolerated. 
         [0004]    One conventional implementation of a sense resistor provides an external sense resistor coupled to components of an IC.  FIG. 1  is a circuit schematic showing a circuit accessing an external sense resistor according to one example of the prior art. An example circuit  100  uses an external sense resistor  110  coupled to an IC  120 . Circuit  100  includes an output driver  102  and a sense analog-to-digital converter (ADC)  104 . Output driver  102  and sense ADC  104  may be part of, but not necessarily all of, circuit  100 . Output driver  102  drives an output signal at its output through pin or ball  106 . The external resistor  110  and a load  114  are coupled in series between pin or ball  106  and ground  122 . An external capacitor  112  is coupled in parallel to the external resistor  110 . The sense ADC  104  receives input through pins or balls  108  and  109 , and the sense ADC  104  generates an output signal at output  111 , which may be internal to an IC  120 . The external resistor  110  is coupled across pins or balls  108  and  109 . A short circuit switch  116  is coupled to pin  109 , which may be used to test a robustness of the output driver  102  and resistor  110 . Current through external resistor  110  generates a voltage across external resistor  110  that can be read as a voltage difference across the pins or balls  108  and  109  as an analog signal and converted to a digital signal by sense ADC  104 . That digital signal may be used as feedback for an intelligent component, such as a controller in the IC  120 . 
         [0005]    In the design of circuit  100 , external resistor  110  is not part of the IC  120 , allowing the resistance value for external sense resistor  110  to be selected such that external resistor  100  can withstand or tolerate large short-circuit currents. However, a sense resistor with a high or higher resistance value typically equates to a larger sized resistor. Further, sizing a sense resistor with a high or higher heat dissipation value to allow tolerance of larger currents generally also results in a larger size resistor. A larger resistor consumes more space or area in an electronic device, which is disadvantageous and particularly disadvantageous in mobile devices. Also, as shown in example circuit  100 , the use of external resistor  110  typically requires one or two additional pins or balls for the IC  120 , shown as pins or balls  108  and  109 . Additional pins or balls generally require additional layout and/or pin-out and also require additional space on the IC  120 . Furthermore, external path  107  to the external resistor  110  and load  114  has an inherent inductance. If this inductance is not offset, then it may cause voltage ringing spikes for circuit  100 . Thus, the use of external resistor  110  necessitates use of external capacitor  112  to offset the inductance. This external capacitor  112  consumes additional space and area in an electronic device that includes circuit  100 . 
         [0006]    An alternative solution to an external resistor is to integrate the resistor into the IC.  FIG. 2  is a circuit schematic showing a circuit having an integrated sense resistor according to one example of the prior art. An example circuit  200  includes an IC  220  with an integrated resistor  202 . Circuit  200  is similar to circuit  100  and includes output driver  102  and sense ADC  104 . Similar to circuit  100 , output driver  102  and sense ADC  104  are included in an IC, and output driver  102  drives an output signal to pin or ball  106 . However, instead of external resistor  110  that is outside of the IC  120 , circuit  200  includes integrated sense resistor  202  internal to the IC  220 . The integrated resistor  202  is coupled between the output driver  102  and pin or ball  106 . Internal nodes  204  and  206  couple integrated resistor  202  to sense ADC  104 . Load  114  is coupled between pin or ball  106  and ground  122 . 
         [0007]    Designing integrated resistor  202  to withstand or tolerate large short-circuit currents requires the integrated resistor  202  to be large in size and consume space and area. The larger area for an IC makes it more challenging to symmetrically lay out the circuit to eliminate mismatches, such as mismatches due to having more than one source of current (e.g., current sources for a p-channel metal-oxide-semiconductor field-effect transistor (MOSFET) (PMOS) driver device and an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) (NMOS) driver device). The requirements for circuit symmetry further constrain the layout of circuit components, such as the layout for the integrated resistor  202 , the current source, the pin or ball, and/or the internal nodes  204  and  206 . 
         [0008]    These symmetry requirements are illustrated in  FIG. 3 .  FIG. 3  is a cross-sectional view showing an integrated circuit at a chip-scale package (CSP) level with an integrated sense resistor according to one example of the prior art. Integrated circuit layout  300  includes sense ADC  104  coupled to integrated sense resistor  202 , which is coupled to pin or ball  106 , such as a Chip-Scale-Package (CSP) output ball. The resistor value for integrated sense resistor  202  is a function of a ratio of its length L to its width W (e.g., L/W), and thus usually has a width W much greater than its length L. In order to maintain symmetry, the ratio L/W needs to be maintained as a constant. Thus, if the length L is made longer, then the width W also will need to be correspondingly made longer, and vice versa if they are made shorter. The integrated resistor  202  may be sensed by ADC  104  through internal sense points  306  and  308  located across the length L. Circuit layout  300  may also include NMOS driver  302  and PMOS driver  304  located at opposite sides of the sense ADC  104  and ball  106 . Mismatches among NMOS driver  302  and PMOS driver  304  that provide multiple current sources can and generally do exist. Thus, a line of symmetry  310  needs to be maintained in order to maintain symmetry for integrated circuit layout  300  and reduce/eliminate mismatches. Also, if symmetry for integrated circuit layout  300  is not maintained, then the current values being sensed at the sense points  306  and  308  may not be accurate and/or may be inconsistent. 
         [0009]    Shortcomings mentioned here are only representative and are included simply to highlight that a need exists for improved electrical components, particularly for sense resistors and integrated circuits (ICs) that utilize those sense resistors employed in consumer-level devices, such as mobile phones. Embodiments described herein address certain shortcomings but not necessarily each and every one described here or known in the art. 
       SUMMARY 
       [0010]    In some embodiments, an integrated sense resistor may be included within an integrated circuit (IC), and the integrated sense resistor may be surroundingly positioned and coupled to a packaging connection, such as a pin or ball or Chip-Scale Package (CSP) output ball, or be surroundingly positioned around a connection to the packaging connection (e.g., pin or ball). The integrated sense resistor may be shaped such that more surface area of the integrated sense resistor is coupled to be positioned closer or in actual contact with the pin or ball than the prior art straight layered integrated sense resistor solutions such as shown as resistor  202  in  FIG. 2 . That is, the long straight shape of the prior art resistor  202  causes the size of the resistor  202  to consume a large die area as the resistor  202  needs to accommodate larger currents or larger resistance values. In contrast, by shaping an integrated resistor to be not straight, such as to surround or wrap a connection to a pin or ball of the integrated circuit, the die area for the resistor may be reduced. 
         [0011]    The integrated resistor may take on any of a number of shapes that allow the integrated resistor to not be straight. In some embodiments, the integrated sense resistor is made into a non-straight shape that entirely surrounds or wraps around the pin or ball. Such non-straight shapes include, but are not limited to, closed shape resistors such as a circular or oval shape, a box or rectangular shape, a triangular shape, a polygonal shape, etc. In some embodiments, the integrated sense resistor is made into a non-straight shape that only partially surrounds the pin or ball. Such non-straight shapes include, but are not limited to, open shape resistors such as an open-circular or semi-circular shape, an open-sided box or rectangular shape, an open-sided triangular shape, an angular shape, a curved shape, etc. 
         [0012]    According to one embodiment, an integrated circuit may include an integrated resistor. The integrated circuit may include a packaging connection, such as an output ball. The integrated circuit may also include a non-straight resistor layer that forms the integrated resistor and that is coupled to the packaging connection (e.g., output ball), wherein the non-straight resistor layer at least partially surrounds the packaging connection or at least partially surrounds a connection to the packaging connection. 
         [0013]    In certain embodiments, the non-straight resistor layer may be coupled to the packaging connection (e.g., output ball) such that the non-straight shape resistor layer at least partially surrounds, and optionally entirely surrounds, the packaging connection (e.g., output ball) or a connection to the packaging connection (e.g., output ball), and optionally may be coupled to the packaging connection (e.g., output ball); the non-straight resistor layer may be coupled to the packaging connection (e.g., output ball) such that the non-straight shape resistor layer at least partially surrounds the packaging connection (e.g., output ball); and/or the non-straight shape resistor layer may be coupled to the packaging connection (e.g., output ball) so that the non-straight shape resistor layer entirely surrounds and is in contact with a connection to the packaging connection (e.g., output ball) or the output ball itself. 
         [0014]    According to another embodiment, a method of forming an integrated resistor for an integrated circuit may include forming a non-straight resistor layer; and/or coupling the non-straight resistor layer to a packaging connection (e.g., output ball) of the integrated circuit, wherein the step of forming the non-straight resistor layer may include forming the non-straight resistor layer to at least partially surround the packaging connection (e.g., output ball) or a connection to the packaging connection (e.g., output ball). 
         [0015]    In certain embodiments, the step of forming the non-straight resistor layer may include shaping the non-straight shape resistor layer to entirely surround the packaging connection (e.g., output ball); and/or the step of forming the non-straight resistor layer may include shaping the non-straight shape resistor layer to partially or entirely surround and be in contact with the packaging connection (e.g., output ball) or entirely surround a connection to the packaging connection (e.g., output ball). 
         [0016]    The foregoing has outlined rather broadly certain features and technical advantages of embodiments of the present invention in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those having ordinary skill in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same or similar purposes. It should also be realized by those having ordinary skill in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. Additional features will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended to limit the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    For a more complete understanding of the disclosed system and methods, reference is now made to the following descriptions taken in conjunction with the accompanying drawings. 
           [0018]      FIG. 1  is a circuit schematic showing a circuit accessing an external sense resistor according to one example of the prior art. 
           [0019]      FIG. 2  is a circuit schematic showing a circuit having an integrated sense resistor according to one example of the prior art. 
           [0020]      FIG. 3  is a top-down view showing an integrated circuit at a chip-scale package (CSP) level with an integrated sense resistor according to one example of the prior art. 
           [0021]      FIG. 4  is a top-down view showing an integrated circuit at a chip-scale package (CSP) level with an example non-straight integrated sense resistor according to one embodiment of the disclosure. 
           [0022]      FIG. 5  is cross-sectional view showing an integrated circuit with an example non-straight sense resistor and an example integration with other components of the integrated circuit according to one embodiment of the disclosure. 
           [0023]      FIG. 6  is a top-down view showing an integrated circuit with an example non-straight sense resistor according to one embodiment of the disclosure. 
           [0024]      FIG. 7  is an example circuit showing a function of a non-straight sense resistor in an integrated circuit (IC) according to one embodiment of the disclosure. 
           [0025]      FIG. 8  is a top-down view showing an integrated circuit with an example non-straight sense resistor with varying length and/or offsets according to one embodiment of the disclosure. 
           [0026]      FIG. 9A  is a top-down view showing an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. 
           [0027]      FIG. 9B  is a cross-sectional view showing an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. 
           [0028]      FIG. 9C  is a top-down view showing a top metal layer of an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. 
           [0029]      FIG. 9D  is a top-down view showing a metal layer below the top metal layer of an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. 
           [0030]      FIG. 9E  is an example circuit showing a function of a non-straight sense resistor with multiple circles in an integrated circuit (IC) according to one embodiment of the disclosure. 
           [0031]      FIG. 10  is a flow chart showing an example manufacturing process for manufacturing an integrated circuit with integrated non-straight sense resistor according to one embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    In one embodiment, the integrated sense resistor is positioned near a Chip-Scale Package (CSP) output ball as shown in  FIG. 4 .  FIG. 4  is a top-down view showing an integrated circuit at a chip-scale package (CSP) level with an example non-straight integrated sense resistor according to one embodiment of the disclosure. An integrated circuit (IC)  400  may include a sense ADC  404  coupled to a non-straight layered integrated sense resistor  402 . The integrated circuit  400  is also shown in  FIG. 6 .  FIG. 6  is a top-down view showing an integrated circuit with an example non-straight sense resistor and an example integration with other components of the integrated circuit according to one embodiment of the disclosure. 
         [0033]    The sense resistor  402  shown in  FIG. 4  is a circular shaped integrated sense resistor  402 , however the sense resistor  402  may take other shapes, such as the shapes described above. Non-straight layered integrated sense resistor  402  can be formed as a resistor layer (e.g., integrated sense resistor layer). The sense resistor  402  may include any suitable material for an integrated circuit (IC), including Tantalum Nitride (TaN). Circular shaped integrated sense resistor  402  may be coupled to a pin or ball (e.g., CSP output ball) or other packaging connection  406  such that circular shaped integrated sense resistor  402  is surroundingly positioned or wrapped around a packaging connection, such as a pin or ball, (e.g., CSP output ball)  406  and/or positioned or wrapped around a connection (e.g., top metal  502  of  FIG. 5 ) to the pin or ball  406 . The circular shaped integrated sense resistor  402  may have more surface area but may be shaped to consume or take up less space or area within the IC  400  than the prior art straight layered integrated sense resistor solutions. The reduced space and/or larger surface area may be a result of the non-straight or circular shaped integrated sense resistor  402  being surroundingly positioned or wrapped around the pin or ball  306  (e.g., closer in proximity or in contact with the pin or ball  306 ). Also, because the circular shaped integrated sense resistor  402  is surroundingly positioned or wrapped around the pin or ball  406 , the integrated sense resistor  402  is in closer proximity or in contact with the pin or ball  406 , which may allow for more efficient dissipation of heat away from the integrated sense resistor  402  and onto an external board (not shown) to which the integrated circuit  402  is attached. Because the circular shaped integrated sense resistor  402  can be larger in surface area than prior art layered integrated sense resistors, circular shaped integrated sense resistor  402  may provide the ability to carry more current than conventional straight layered integrated sense resistors. In some embodiments, certain shapes, such as circular shapes, for the integrated sense resistor  402  may provide a current density that is more uniform than the current density that is provided with conventional integrated sense resistors, such as integrated sense resistor  202  of  FIG. 2 . 
         [0034]    The sense resistor  402  may be coupled to circuitry for performing measurements within integrated circuit  400 , including portions of IC  400  not shown. Contact with the sense resistor  402  may be made through sense points  414  and  416 . In some embodiments, the sense points  414  and  416  may be located across the length of the circular shaped integrated sense resistor  402 . The sense points  414  and  416  may be coupled to a sense analog-to-digital converter (ADC)  404 . 
         [0035]    The integrated circuit  400  may include other components near the integrated sense resistor  402 . In one embodiment, the nearby components may include a n-type metal oxide semiconductor (NMOS) device  408 B, such as a driver, comprising one or more n-channel transistors and a p-type metal oxide semiconductor (PMOS) device  408 A, such as a driver, comprising one or more p-channel transistors. The combination of NMOS device  408 B and PMOS device  408 A may form complementary metal oxide semiconductor (CMOS) circuitry. In one embodiment, the devices  408 A and  408 B may be located at opposite sides of pin or ball  406 . 
         [0036]    The integrated circuit  400  may be easier to layout symmetrically around a line of symmetry  410  than conventional ICs with integrated sense resistors. The easier symmetrical layout may be a result of the non-straight or circular shape of integrated sense resistor  402  and/or the reduced space or area consumption compared to conventional integrated sense resistors. Mismatches among NMOS device  408 B and PMOS device  408 A that provide multiple current sources may be minimized or eliminated if sense points  414  and  416  are located along a line of symmetry  410 . Symmetrical layout may be particularly important in embodiments having mismatch between the devices  408 A and  408 B, such as mismatches that occur with having multiple current sources. Although sense points  414  and  416  may be shown in certain positions in  FIG. 4 , the sense points may also be located in other positions. For example, multiple pairs of sense points may be used in the integrated circuit  400  and symmetry maintained if corresponding pairs are located at symmetric positions relative to the line of symmetry  410 . 
         [0037]    Layout constraints of integrated circuit  400  may be eased compared with conventional circuits, such as circuit  300  of  FIG. 3 . The easier layout constraints may be a result of increased flexibility in the locations of sense points  414  and  416  for non-straight or circular shaped integrated sense resistor  402  compared with the conventional integrated sense resistor. Further, the layout constraints may be reduced by reducing die area consumed by the integrated sense resistor as a result of its non-straight shape. The design technique for laying out circuit  400  and providing a non-straight or circular shaped integrated sense resistor  402  may be particularly useful when the width W of the integrated sense resistor  402  is larger than the length L, where the width W may be the circumference of the resistor  402  and the length L may be the dimension radially across the resistor  402 . Such a situation may arise in embodiments where a low resistance is needed, such as in embodiments that include a series resistance in a high current path. 
         [0038]    Additional aspects of certain embodiments of an IC with integrated non-straight sense resistor are shown with respect to a cross section along line  1 - 1  of  FIG. 4  in  FIG. 4 .  FIG. 5  is plan cross-sectional view showing an integrated circuit with an example non-straight sense resistor and an example integration with other components of the integrated circuit according to one embodiment of the disclosure. The IC  400 , the circular shaped integrated sense resistor  402 , the pin/ball  406  (e.g., CSP output ball), and the devices  408 A and  408 B are shown in  FIG. 5 . The resistor layer (e.g., layer that forms circular shaped integrated sense resistor  402 ) may be placed or located below a top or upper metal layer  502  such that a redistribution layer (RDL)  504  may be used to minimize the metal resistance of the respective devices  408 A and/or  408 B, and also reduce or minimize mismatch between devices  408 A and  408 B. 
         [0039]    Referring back to  FIG. 4 , if devices  408 A and  408 B are located on one side of pin/ball (e.g., CSP output ball)  406  (e.g., on one side of line  1 - 1 ) and sense points  414  and  416  are located along the line of symmetry  410  on the other side of pin/ball  406  (e.g., on the other side of line  1 - 1 ), then such a layout configuration generally maintains symmetry and minimizes the mismatches between the devices  408 A and  408 B for IC  400 . As described above, more than two sense points may be present and symmetry maintained by locating them symmetrically in relation to the line of symmetry  410 . 
         [0040]    The layout in accordance to embodiments of the present disclosure can be advantageously used whenever a low resistance, high current resistor is needed or desired, particularly at a packaging connection, such as a CSP output pin or ball. Although a sense resistor is one application for embodiments of the present disclosure, they can also be used in other applications, such as to decouple a capacitive load from a driver. Many applications exist for the embodiments disclosed in the present disclosure, and they are not limited to just the sense resistor and other embodiments described in this disclosure. 
         [0041]    In different embodiments, the non-straight shaped integrated sense resistor may partially or fully surround or wrap around an IC pin or ball. Thus, the non-straight shaped integrated sense resistor may have more surface area but consume or take up less space or die area within an IC than conventional integrated sense resistors. Further, the non-straight shaped integrated sense resistor may be in closer proximity or in contact with the pin or ball, which may allow it to efficiently dissipate heat away from the integrated sense resistor and onto an external board (not shown) to which the layout integrated circuit is mounted. In some embodiments, the non-straight shaped integrated sense resistor may be larger in surface area than conventional integrated sense resistors, even while consuming the same or less die area, which may allow a non-straight shaped integrated sense resistor to provide an ability to carry more current than conventional integrated sense resistors. 
         [0042]    A circuit representation of an IC with an integrated sense resistor is shown in  FIG. 7 .  FIG. 7  is an example circuit showing a function of a non-straight sense resistor in an integrated circuit (IC) according to one embodiment of the disclosure. The IC  400  may be shown in a circuit schematic with an integrated resistor  402  with sense points  414  and  416  coupled between devices  408 A and  408 B. Device  408 A may couple the integrated resistor  402  to a positive supply voltage; device  408 B may couple the integrated resistor  402  to a ground or negative supply voltage. The devices  408 A and  408 B may drive a current to an output node  702 , and the sense resistor  402  may be used to measure the current output to the output node  702 . 
         [0043]    As described above, the non-straight integrated sense resistor  402  may take on a number of shapes or structures. One embodiment of the integrated sense resistor  402  may have varying lengths and offsets within the sense resistor  402  as shown in  FIG. 8 .  FIG. 8  is a top-down view showing an integrated circuit with an example non-straight sense resistor with varying lengths and offsets according to one embodiment of the disclosure. An integrated circuit may include an integrated non-straight sense resistor  802  having a varying length along various points of the circumference of the resistor  802  as a result of the circles having different radius and offset components. Sense points  804  and  806  may provide electrical contact to the sense resistor  802 . Sense resistors with varying length, such as shown in  FIG. 8 , may be useful to compensate for unequal currents through the sense resistor. 
         [0044]    Yet another embodiment of the integrated sense resistor  402  may include multiple shapes, such as circles, positioned around each other, such as with concentric circles, as shown in  FIGS. 9A-E .  FIG. 9A  is a top-down view showing an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. Sense resistors  902  may be formed from multiple, and optionally concentric, circles. Each of the circle sense resistors  902  may have two sense points for electrical contact to the sense resistors  902  shown as sense points  904  and  906 . A cross-section through an integrated circuit of the multiple circle integrated sense resistors  902  is shown in  FIG. 9B . Although the circles are shown as concentric circles, in which each circle has a common center and different diameter, the circles may also be slightly offset such that the circles do not share a common center. 
         [0045]      FIG. 9B  is a cross-sectional view showing an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. The multiple circle sense resistors  902  may be formed from resistor layer  912 , which may be made of a resistive material such as Tantalum Nitride (TaN). The resistor layer  912  may be coupled through a metal layer  914  to a top metal layer  916 A-B. The top metal layer may be coupled to a packaging connection such as a pin or ball, or in one embodiment a CSP output ball  918 . A top-down view of the top metal layer  916 A-B of  FIG. 9B  is shown in  FIG. 9C .  FIG. 9C  is a top-down view showing a top metal layer of an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. A top-down view showing a metal layer  914  under the top metal layer  916 A-B is shown in  FIG. 9D .  FIG. 9D  is a top-down view showing a metal layer below the top metal layer of an integrated circuit with an example non-straight sense resistor with multiple circles according to one embodiment of the disclosure. 
         [0046]    The concentric circle integrated sense resistors may provide multiple resistances that may be accessed by an integrated circuit. In one example, the sense resistors may be coupled in parallel as shown in the circuit equivalent of  FIG. 9E .  FIG. 9E  is an example circuit showing a function of a non-straight sense resistor with multiple circles in an integrated circuit (IC) according to one embodiment of the disclosure. The integrated circuit may include PMOS and NMOS devices  408 A and  408 B, respectively, as shown in other embodiments. The multiple circle integrated sense resistors are shown as resistors  902 A and  902 B coupled in parallel between sense points  904  and  906 . Although only two resistors  902 A and  902 B are shown in  FIG. 9E , additional resistances may be added with additional circles in the embodiments of  FIGS. 9A-D . 
         [0047]    For a desired total resistance value, implementing multiple rings as shown in  FIGS. 9A-9E  may reduce a current density in each individual ring. This may improve the electromigration performance of the integrated sense resistor and wiring, such as vias, coupled to the sense resistor to provide better reliability. The multiple rings may also reduce the voltage coefficient of the integrated sense resistance to obtain better resistance linearity. Further, the multiple rings may also reduce the self-heating as the same power is dissipated over a larger area than with a single ring to provide better resistance linearity even with the same temperature coefficient. 
         [0048]    In one embodiment, an integrated circuit with multiple circle integrated sense resistors may provide current sensing through the integrated sense resistors with a low temperature coefficient. This may be particularly advantageous when a desired integrated sense resistor has a resistance value of less than a few Ohms, such as less than one Ohm. 
         [0049]    The radius of the multiple rings may be as small as a radius of the packaging pin/ball, such that the mechanical stress of the assembly does not significantly affect the performance of the resistor ring. The radius of the multiple rings may be as large as the spacing of others balls in the integrated circuit allows, such that the concentric rings do not interfere with any other ball in the integrated circuit. A length of the multiple rings may be selected, in part, to obtain a desired resistance value for the integrated sense resistor. The length may also be affected by resistivity of the material of the sense resistor and expected current density through the multiple rings. The radius of the multiple rings or of a single ring is not limited in this way. The radius may be smaller than the packaging ball when it is fit below the packaging ball. The radius may also be larger to extend under other adjacent balls. 
         [0050]    An integrated sense resistor may be manufactured using a combination of known semiconductor manufacturing techniques. One example of a new manufacturing process for manufacturing the integrated sense resistor in an integrated circuit is shown in  FIG. 10 .  FIG. 10  is a flow chart showing an example manufacturing process for manufacturing an integrated circuit with integrated non-straight sense resistor according to one embodiment of the disclosure. A method  1000  may be used to manufacture an integrated circuit, such as integrated circuit  400  of  FIG. 5 . The IC  400  of  FIG. 5  may be referred throughout the method  1000  as an example of an IC that may be manufactured according to the method  1000 . However, the method  1000  may produce ICs other than IC  400  of  FIG. 5  and/or may be adapted to produce ICs other than IC  400  of  FIG. 5 . For example, variations of method  1000  may be used to manufacture embodiments of the disclosure described with reference to  FIG. 8  and  FIG. 9  or the various shapes of integrated resistors described above or the other various embodiments described above. 
         [0051]    The method  1000  may begin at block  1002  with forming transistors on a substrate. For example, PMOS and NMOS transistors may be formed on a silicon substrate, such as transistors found in devices  408 A and  408 B of  FIG. 5 . Next, at block  1004 , contacts to the transistors may be formed. Contacts  512 A and  512 B may couple the devices  408 A and  408 B, respectively, to other layers and/or other components within IC  400 . Then, at block  1006 , metal layers and/or vias may be formed, to a top layer. For example, metal layers  514 A and  514 B may be formed to couple the contacts  512 A and  512 B to a top metal  502 . Next, at block  1008 , a resistor layer may be formed integrated with the IC. For example, integrated non-straight sense resistor  402  may be formed in the IC  400 . At block  1008 , the integrated sense resistor  402  may be formed in between some layers formed at block  1006 , or the integrated sense resistor  402  may be formed after all of the layers but the top metal  502  are formed at block  1006 . Then, at block  1010 , a via layer may be formed above the resistor layer. For example, vias  516  may be formed above the integrated resistor  402  and/or metal layers  514 A and  514 B and/or above other metal layers. Next, at block  1012 , a top metal layer may be formed on the IC. For example, the top metal  502  may be formed and coupled to the vias  516  that couple the top metal  502  to the integrated sense resistor  402  and/or the devices  408 A and  408 B. Then, at block  1014 , a redistribution layer (RDL) may be formed on the top metal layer. For example, referring back to  FIG. 5 , the RDL  504  may be formed on the top metal  502 . Next, at block  1016 , packaging solder balls may be formed on the RDL. For example, referring back to  FIG. 5 , CSP ball  406  may be formed on the top metal  504 . 
         [0052]    The schematic flow chart diagram of  FIG. 10  is generally set forth as a logical flow chart diagram. As such, the depicted order and labeled steps are indicative of aspects of the disclosed method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Although various arrow types and line types may be employed in the flow chart diagram, they are understood not to limit the scope of the corresponding method. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the method. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. 
         [0053]    If implemented in firmware and/or software, functions described above may be stored as one or more instructions or code on a computer-readable medium. Examples include non-transitory computer-readable media encoded with a data structure and computer-readable media encoded with a computer program. Computer-readable media includes physical computer storage media. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise random access memory (RAM), read-only memory (ROM), electrically-erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc includes compact discs (CD), laser discs, optical discs, digital versatile discs (DVD), floppy disks and Blu-ray discs. Generally, disks reproduce data magnetically, and discs reproduce data optically. Combinations of the above should also be included within the scope of computer-readable media. 
         [0054]    In addition to storage on computer readable medium, instructions and/or data may be provided as signals on transmission media included in a communication apparatus. For example, a communication apparatus may include a transceiver having signals indicative of instructions and data. The instructions and data are configured to cause one or more processors to implement the functions outlined in the claims. 
         [0055]    Although the present disclosure and certain representative advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.