Abstract:
A switching regulator may include an inductor housing, a board, and one or more electrical components. The inductor housing may house an inductor and one or more wires. The board may include one or more board traces and one or more solder pads. The electrical components may include one or more chips, capacitors, voltage sources, and/or other electrical components. The inductor housing may be attached to the board to create a space between the inductor housing and the board. The space may be created underneath the inductor housing and above the board. One or more electrical components may be attached to the board. One or more electrical components may be disposed within the space.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 62/274,554, filed Jan. 4, 2016, and entitled “POWER CONVERSION DEVICE WITH INTEGRATED DISCRETE INDUCTOR.” The entirety of the aforementioned application is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure generally relates to a technical field of semiconductor devices, and particularly to power conversion devices with integrated discrete inductors. 
       BACKGROUND 
       [0003]    Voltage regulators, such as DC to DC converters, are used to provide stable voltage sources for electronic systems. Efficient DC to DC converters are particularly needed for low power devices. One type of DC-to-DC converters is a switching voltage regulator. A switching voltage regulator generates an output voltage by alternately coupling and decoupling an input DC voltage source with a load. The coupling and decoupling action can be performed by a switch, while a low pass filter comprising a capacitor and an inductor can be used to filter the output of the switch to provide a DC output voltage. 
         [0004]      FIG. 1  shows an example implementation of a “buck” type switching regulator, which can perform a DC-DC down conversion. Referring to  FIG. 1 , circuit  100  includes a voltage source  103 , a switching regulator  102  and a load  113 . Switching regulator  102  is coupled to the voltage source  103  through an input terminal  114 . Switching regulator  102  is also coupled to the load  113 , which can be another electronic circuit that draws current, via an output terminal  112 . Switching regulator  102  includes a switching circuit  116 , which serves as a power switch for alternately coupling and decoupling input terminal  114  to an intermediate terminal LX node  109 . Switching circuit  116  includes a first transistor  107  and a second transistor  108 . Typically both transistors  107  and  108  can be implemented as metal oxide semiconductor field effect transistor (MOSFETs). Transistor  107  has a drain connected to input terminal  114 , a source connected to an intermediate terminal  109 , and a gate connected to a control line  105 . Transistor  108  has a drain connected to intermediate terminal LX node  109 , a source connected to a low voltage potential  115  (e.g. a ground), and a gate connected to a control line  106 . 
         [0005]    Switching regulator  102  includes a controller  104  to control the operation of switching circuit  116  via control lines  105  and  106 . Switching regulator  102  also has an output filter  117 , which includes an inductor  110  connected between intermediate terminal  109  and output terminal  112 , and a capacitor  111  connected in parallel with load  113 . Controller  104  causes switching circuit  116  to alternate between a first conduction period, where first transistor  107  is enabled and second transistor  108  is disabled to bring intermediate terminal  109  to a voltage substantially equal to the input voltage, and a second conduction period, where first transistor  107  is disabled and second transistor  108  is enabled to bring intermediate terminal  109  to a voltage substantially equal to that of low voltage potential  115 . This results in a rectangular waveform, which toggles substantially between input voltage and a voltage equal to voltage potential  115 , at LX node  109 , which can act an intermediate terminal.  109  is coupled to output terminal  112  via output filter  117 . Output filter  117  converts the rectangular waveform at intermediate terminal  109  to a substantially DC voltage at output terminal  112 . The magnitude of the output DC voltage at terminal  112  depends on the duty cycle of the rectangular waveform at intermediate terminal  109 . 
         [0006]    With widespread use of BCD (Bipolar-CMOS-DMOS) technology, it is common to integrate controller  104 , switching circuit  116 , as well as high precision feedback circuit (not shown in  FIG. 1 ) on a single controller chip. The controller chip can have an output port that corresponds to the LX node  109 . The controller chip can then be connected to a discrete inductor (e.g., inductor  110 ) at the output port that corresponds to the LX node  109  to form the switching regulator  102 . The external inductor can also be connected to other discrete components (e.g., capacitor  111 ) to form an output terminal (e.g., output terminal  112 ) of the switching regulator  102 . 
         [0007]      FIG. 2  illustrates a way of placing the controller chip and the discrete components on a printed circuit board (PCB) to form the switching regulator  102  of  FIG. 1 . As shown in  FIG. 2 , system  200  includes a controller chip  202  which can include, for example, controller  104  and switching circuit  116  of  FIG. 1 . System  200  also includes capacitor  111 , and inductor  110  of  FIG. 1 .  FIG. 2  also illustrates a number of board traces and solder pads arranged to be LX node  109 , vout  112 , yin  114 , and GND  115  of  FIG. 1 . System  200  also includes a capacitor  203  (not shown in  FIG. 1 ) connected to yin  114  to act as a by-pass capacitor to further reduce the switching noise at that node. As shown in  FIG. 2 , controller chip  202 , is placed adjacent to capacitors  111  and  203 . Capacitors  111  and  203  are also placed adjacent to inductor  110 . 
         [0008]    The arrangement of the components in  FIG. 2 , while simple to implement, brings about a few drawbacks. First, such an arrangement takes up substantial board space, since each of the aforementioned components occupies a different area on a board surface. Second, relatively long board traces are needed to connect between the components, leading to huge parasitic capacitance at some of the critical nodes. For example, as shown in  FIG. 2 , the length of LX node  109  is about 3 cm. As LX node  109  an intermediate node for charging and discharging of inductor  110  and capacitor  111 , by first and second transistors  107  and  108 , reducing the length of LX node  109  and the associated parasitic capacitance can reduce switching loss and improve the efficiency of the power converter. 
         [0009]      FIG. 3  illustrates an approach of component arrangement to form the switching regulator  102  of  FIG. 1 , for reducing the board space. As shown in  FIG. 3 , switching regulator  300  includes a controller chip  302  which can include, for example, controller  104  and switching circuit  116  of  FIG. 1 . Switching regulator  300  also includes inductor  110 , which is housed inside an inductor housing  304 . Inductor housing  304  also houses internal wires  309   a - b,  with wire  309   a  soldered to board  306  at solder pad  308   a.  Controller chip  302  also includes controller pads  307   a  and  307   b  which provide electrical connection to internal components of controller chip  302  (e.g., switching circuit  116  at LX node  109 ). To reduce the space occupied by switching regulator  300 , controller chip  302  is disposed on top of inductor housing  304 . Bond wire  310   a  is configured to provide electrical connection between controller pads  307   a  and solder pad  308   a,  thereby providing electrical connection between inductor  110  and controller chip  302  (e.g., LX node  109 ). Bond wire  310   b  is configured to provide electrical connection between controller pads  307   b  and solder pad  308   b  on the board. Solder pad  308   b  enables controller chip  302  to be electrically connected to other components on board  306 . 
         [0010]    While the arrangement shown in  FIG. 3  reduces the board space required for placing controller chip  202  and inductor housing  304 , the bond wires  310   a  and  310   b  are still relatively long, and can contribute to considerable amount of parasitic capacitance and resistance. 
         [0011]      FIG. 4  illustrates an approach of component arrangement for addressing the drawbacks of  FIG. 3 . As shown in  FIG. 4 , switching regulator  400  includes a controller chip  402  which can include, for example, controller  104  and switching circuit  116  of  FIG. 1 . Controller chip  402  can be a flip-chip device and include solder balls  408   a - b,  which can act as terminals configured to provide electrical connections to, for example, controller  104  and switching circuit  116  disposed within controller chip  402 . Switching regulator  400  also includes inductor  110 , which is housed inside an inductor housing  404 . Inductor housing  404  includes solder pads  410  configured to provide electrical connections to inductor  110  via internal wires  409   a.  As shown in  FIG. 4 , inductor  110  is electrically connected to controller chip  402  via solder ball  408   a  and solder pads  410 . Inductor housing  404  is disposed on board  406 . To reduce the space occupied by switching regulator  400 , controller chip  402  is disposed on top of inductor housing  404 . 
         [0012]    With the arrangement of  FIG. 4 , where the electrical connections between controller chip  402  and inductor housing  404  are provided by solder balls and pads, the parasitic capacitance associated with those electrical connections (including those for LX node  109 ) can be reduced. However, there are still numerous drawbacks with the arrangement of  FIG. 4 . First, while the solder pads and solder balls provide good electrical connections between the inductor and the controller (e.g., the LX node), they are exposed to the environment, and noises can be coupled into the electrical connection. The noise can affect the voltage output of switching regulator  400 . Second, with controller  402  separated from board  406  by inductor housing  404 , the arrangement of  FIG. 4  can degrade other electrical connections for controller  402 , such as yin  114 , GND  115 , vout  112 , etc. Long bond wires may still be needed to providethese electrical connections, which can contribute considerable amount of parasitic capacitance and resistance to those connections. 
         [0013]    Therefore, while the arrangement of  FIG. 4  improves the electrical connection between the controller and the inductor, it can degrade the rest of the electrical connections for the controller, and the performance of switching regulator  400  can still be compromised. 
         [0014]    Hence, there is a need for a technique to arrange the components of switching regulator, not only to reduce the board area requirement but also to provide good electrical connections and good insulation for all of the components, such that the regulator can be made more compact and can be more easily fitted into devices of small form factors, such as mobile phones. 
       SUMMARY 
       [0015]    A switching regulator may include an inductor housing, a board, and one or more electrical components. The inductor housing may house an inductor and one or more wires. The board may include one or more board traces and one or more solder pads. The electrical components may include one or more chips, capacitors, voltage sources, and/or other electrical components. The inductor housing may be attached to the board to create a space between the inductor housing and the board. The space may be created underneath the inductor housing and above the board. One or more electrical components may be attached to the board. One or more electrical components may be disposed within the space. 
         [0016]    In one aspect of the disclosure, the switching regulator may include a chip. The chip may include a flip chip. The chip may include a first terminal. The chip may be attached to the board and disposed within the space. The inductor housing may house a first wire electrically coupled to the inductor. The board may include a first board trace. The first board trace may electrically couple the first terminal with the first wire. In some implementations, the inductor may be disposed over the chip. In some implementations, the board may include a first solder pad and a second solder pad electrically coupled via the first board trace. The first solder pad may be soldered to the first wire and the second solder pad may be soldered to the first terminal. In some implementations, the board may include a groove that includes a surface. The chip and the inductor housing may be attached to the surface of the groove. In some implementations, the inductor housing may be mounted on the chip using a non-conductive adhesive. The non-conductive adhesive may include a non-conductive die-attach-film. 
         [0017]    In some implementations, the switching regulator may include a capacitor. The capacitor may include a second terminal. The capacitor may be attached to the board and disposed within the space. The inductor housing may house a second wire electrically coupled to the inductor. The board may include a second board trace. The second board trace may electrically couple the second terminal with the second wire. In some implementations, the board may include a third solder pad and a fourth solder pad electrically coupled via the second board trace. The third solder pad may be soldered to the second wire and the fourth solder pad may be soldered to the second terminal. In some implementations, the capacitor may be attached to the surface of the groove. 
         [0018]    In another aspect of the disclosure, the switching regulator may include a chip and a voltage source. The chip may include a flip chip. The chip may include a first terminal. The voltage source and the inductor housing may be attached to a first surface of the board. The voltage source may be disposed within the space. The chip may be attached to a second surface of the board. The chip may not be disposed within the space. The inductor housing may house a first wire electrically coupled to the inductor. The board may include a first board trace. The first board trace may electrically couple the first terminal with the first wire. In some implementations, the board may include a first solder pad and a second solder pad electrically coupled via the first board trace. The first solder pad may be soldered to the first wire and the second solder pad may be soldered to the first terminal. In some implementations, the board may include a groove that includes the second surface. In some implementations, the inductor housing may be mounted on the voltage source using a non-conductive adhesive. The non-conductive adhesive may include a non-conductive die-attach-film. 
         [0019]    In some implementations, the switching regulator may include a capacitor. The capacitor may include a second terminal. The capacitor may be attached to the second surface of the board. The capacitor may not be disposed within the space. The inductor housing may house a second wire electrically coupled to the inductor. The board may include a second board trace. The second board trace may electrically couple the second terminal with the second wire. In some implementations, the board may include a third solder pad and a fourth solder pad electrically coupled via the second board trace. The third solder pad may be soldered to the second wire and the fourth solder pad may be soldered to the second terminal. 
         [0020]    In another aspect of the disclosure, a switching regulator system may include an inductor housing and a board. The inductor housing may include an inductor, a first wire coupled to the inductor, and a second wire coupled to the inductor. The board may include a first board trace and a second board trace. The first board trace may be configured to be coupled to the first wire and the second board trace may be configured to be coupled to the second wire. The inductor housing may be configured to be attached to the board to create a space between the inductor housing and the board. One or more electrical components may be disposed within the space. 
         [0021]    These and other objects, features, and characteristics of the system and/or method disclosed herein, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a block diagram of a buck switching regulator; 
           [0023]      FIG. 2  is a printed circuit board (PCB) layout illustrating a placement of components of a buck switching regulator; 
           [0024]      FIG. 3  is a schematic illustrating another placement of components of a buck switching regulator; 
           [0025]      FIG. 4  is a schematic illustrating another placement of components of a buck switching regulator; 
           [0026]      FIG. 5  is a schematic illustrating an exemplary switching regulator consistent with embodiments of the present disclosure; 
           [0027]      FIG. 6  is a schematic illustrating an exemplary switching regulator consistent with embodiments of the present disclosure; 
           [0028]      FIG. 7  is a schematic illustrating an exemplary switching regulator consistent with embodiments of the present disclosure; and 
           [0029]      FIG. 8  is a schematic illustrating an exemplary switching regulator consistent with embodiments of the present disclosure; and 
           [0030]      FIG. 9  is a printed circuit board (PCB) layout illustrating the placement of components of an exemplary switching regulator consistent with embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 5  illustrates an exemplary switching regulator  500  consistent with embodiments of the present disclosure. As shown in  FIG. 5 , switching regulator  500  includes a controller chip  502  which can include, for example, controller  104  and switching circuit  116  of  FIG. 1 . Switching regulator  300  also includes inductor  110 , which is housed inside an inductor housing  504  and is raised above board  506 , creating a space  507  underneath the inductor. Controller  502  and other components of switch regulator  500  (e.g., capacitor  111 ) can be disposed within space  507  underneath inductor  110  and attached to board  506 . In some embodiments, inductor housing  504  can be mounted on controller chip  502  using a non-conductive die-attach-film (DAF) or any other non-conductive adhesive, to further strength the attachment of controller chip  502  to board  506 . 
         [0032]    As shown in  FIG. 5 , inductor housing  504  also houses internal wires  509   a  and  509   b,  while board  506  also includes board traces  510   a - b  and solder pads  512   a - d.  Controller chip  502  can be a flip-chip device and include solder ball  508   a,  which can be configured as a terminal of controller chip  502 , and can be soldered to solder pads  512   b.  Controller chip  502  can also include solder ball  508   b  (not shown in  FIG. 5 ) configured to be soldered to other solder pads of board  506  (not shown in  FIG. 5 ) to form other electrical connections (e.g. GND  115 ). Internal wire  509   a  can also be soldered to solder pad  512   a.  With board trace  510   a  providing electrical connection between solder pads  512   a - b,  an electrical connection can be formed between inductor  110  and controller chip  502  (e.g., LX node  109 ). Moreover, with capacitor  111  soldered to solder pad  512   c  and internal wire  509   b  soldered to solder pad  512   d,  and board trace  510   b  providing electrical connection between solder pads  512   c - d,  an electrical connection can also be formed between inductor  110  and capacitor  111  (e.g., vout  112 ). 
         [0033]    With an arrangement according to  FIG. 5 , inductor  110  and controller chip  502  can be vertically stacked instead of being disposed side-by-side, thereby less board space is required to place these components. Moreover, the amount of noise coupled into the electrical connection between having inductor  110  and controller chip  502  can be reduced, since inductor  110  and controller chip  502  are electrically insulated except at the points of electrical contacts (e.g., at solder pads  512   b - c  and solder balls  508   a - b ), while majority of the electrical connections (e.g. internal wires  509   a - b,  board traces  510   a - b ) are also insulated from the environment. Furthermore, both the internal wires  509   a - b  and board traces  510   a - b  can be made very short, giving good electrical connections between inductor  110  and controller chip  502 . This is because the length of internal wires  509   a - b  is largely determined by thickness of space  507 , which is typically in the order of millimeters to accommodate the thickness of a controller chip or of a capacitor. Board traces  510   a - b  can also be made very short if solder ball  508   a - b  is at a short distance from internal wires  509   a - b,  which is the case when controller chip  502  and capacitor  111  are disposed beneath inductor  110 . Lastly, unlike switch regulator  400  in which the controller chip is raised from the board, in switch regulator  500  the controller chip is attached to the board, and can have good electrical connections with other components (e.g., input power supply, ground, etc.) via other board traces embedded within board  506  (not shown in  FIG. 5 ). Likewise, inductor  110  can also be connected to other components via board traces. As a result, with an arrangement according to  FIG. 5 , not only that the components will occupy less board space, but also that good electrical connection, via the board traces, as well as good insulation can be provided between the components. 
         [0034]      FIG. 6  illustrates an exemplary switching regulator  600  consistent with embodiments of the present disclosure. As shown in  FIG. 6 , switching regulator  600  includes most of the components of switching regulator  500 , except that board  606 , on which controller chip  502 , capacitor  111 , and inductor housing  504  are mounted, includes a groove  608 . Solder pads  512   a - d  can be disposed on a groove surface  620  of groove  608 , and broad traces  510   a - b  can also disposed under groove surface  620 . Controller chip  502 , capacitor  111 , and inductor housing  504  can be mounted on groove surface  620  and soldered to solder pads  512   a - d.    
         [0035]    In addition to reducing board space requirement and providing good electrical connection and insulation among the components, the arrangement as shown in  FIG. 6  also reduces a vertical height of switching regulator  600  compared to switching regulator  500 . As a result, switching regulator  600  can be made even more compact than switching regulator  500 . 
         [0036]      FIG. 7  illustrates an exemplary switching regulator  700  consistent with embodiments of the present disclosure. As shown in  FIG. 7 , switching regulator  700  includes controller chip  502 , capacitor  111 , and inductor  110 , which is housed inside inductor housing  504  and is raised above board  706 , creating a space  507  underneath the inductor. Space  507  can be used to accommodate, for example voltage source  103  of  FIG. 1 , which provides the input voltage to switching regulator  700 . In this embodiment, inductor housing  504  is disposed on board surface  707   a  , while controller chip  502  and capacitor  111  are disposed on board surface  707   b,  which is on an opposite side to board surface  707   a  . Board  706  further includes solder pads  712   a  and  712   d  on board surface  707   a  , and solder pads  712   b  and  712   c  on board surface  707   b.  Solder pads  712   a  and  712   b  are electrically connected via board trace  710   a,  and solder pads  712   c  and  712   d  are electrically connected via board trace  710   b.  Internal wires  509   a  and  509   b  can be soldered to solder pads  712   a  and  712   d,  while capacitor  111 , as well as solder ball  508   a  of controller chip  502 , can be soldered to solder pads  712   b  and  712   c,  to form the electrical connections for LX node  109  and vout  112 . 
         [0037]    With an arrangement according to  FIG. 7 , inductor  110  and controller chip  502  can be vertically stacked instead of being disposed side-by-side, thereby less board space is required to place these components. Besides, by distributing the components between two opposite sides of board  706 , the board space requirement can be further reduced, and switching regulator  700  can be made even more compact than, for example, switching regulators  500  and  600  of  FIGS. 5 and 6 , while at the same time retaining the advantages provided by switching regulators  500  and  600 , which include providing good insulation for the controller chip and for the inductor to reduce noise coupling, as well as good electrical connections between the components. 
         [0038]      FIG. 8  illustrates an exemplary switching regulator  800  consistent with embodiments of the present disclosure. As shown in  FIG. 8 , switching regulator  800  includes most of the components of switching regulator  700 , except that board  806 , on which controller chip  502 , capacitor  111 , and inductor housing  504  are mounted, includes a groove  808 . Solder pads  712   b  and  712   c  can be disposed on a groove surface  820  of groove  808 . Controller chip  502  and capacitor  111  can be mounted on groove surface  620  and soldered to solder pads  712   b  and  712   c.    
         [0039]    In addition to reducing board space requirement and providing good electrical connection among the components, the arrangement as shown in  FIG. 8  also reduces a vertical height of switching regulator  800  compared to switching regulator  700 . As a result, switching regulator  800  can be made even more compact than switching regulator  700 . 
         [0040]      FIG. 9  is a printed circuit board (PCB) layout  900  illustrating the placement of components of an exemplary switching regulator (e.g., switching regulator  500  of  FIG. 5 ). As shown in  FIG. 9 , controller chip  502  is disposed underneath inductor housing  504  (which houses inductor  110 ). As a result, the connection between controller chip  502  and inductor  110 , such as LX node  109 , can be made very short (less than 1 cm, compared with 3 cm as shown in  FIG. 2 ), and can be provided by a board trace embedded in the PCB, providing good electrical connection and insulation. Also, solder ball  508   b  of controller chip  502  can be soldered to board traces for other electrical connections (e.g., GND  115 ), therefore good electrical connections can be provided for all of the nodes in connection with controller chip  502 . Other electrical connections, such as vout  112 , can be made very short, as capacitor  111  (not shown in  FIG. 9 ) can also be disposed underneath inductor housing  504  (and inductor  110 ). 
         [0041]    Reference throughout this specification to “an embodiment,” “some embodiments,” “one embodiment”, “another example,” “an example,” “a specific examples,” or “some examples,” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as “in some embodiments,” “in one embodiment”, “in an embodiment”, “in another example, “in an example,” “in a specific examples,” or “in some examples,” in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. 
         [0042]    The description of the embodiments is only exemplary, and is not intended to be limiting. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present disclosure. The embodiments shall not be construed to limit the present disclosure. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the figure(s) being described. Because components of embodiments of the present disclosure can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. 
         [0043]    Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure.