Abstract:
An apparatus with an inductor having a conductive loop perpendicular to a metalization plane of a substrate. The conductive loop has an upper element and lower element both parallel to the metalization plane that are connected with a via.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    Aspects of the present disclosure relate in general to electronic circuitry. In particular, aspects of the disclosure include a three-dimensional (3D) printed inductor formed perpendicular to metalization planes of a substrate. 
         [0003]    2. Description of the Related Art 
         [0004]    An inductor (sometimes also referred to as a “choke,” “coil” or “reactor”) is a passive two-terminal electrical component that stores energy in its magnetic field. Typically any conductor has inductance although the conductor is typically wound in loops to reinforce the magnetic field. Due to the time-varying magnetic field inside the coil, a voltage is induced, according to Faraday&#39;s law of electromagnetic induction, which by Lenz&#39;s law opposes the change in current that created it. Inductors are one of the basic components used in electronics where current and voltage change with time, due to the ability of inductors to delay and reshape alternating currents. The quality factor (or Q) of an inductor is the ratio of its inductive reactance to its resistance at a given frequency, and is a measure of its efficiency. The higher the Q factor of the inductor, the closer it approaches the behavior of an ideal, lossless, inductor. 
         [0005]    A Printed Circuit Board (PCB) is a board that mechanically supports and electrically connects electronic components using conductive pathways laminated onto a non-conductive substrate. In addition to connecting electrical components, a two-dimensional (planar) inductor  1100  can be printed on to a printed circuit board, as shown in  FIG. 1A . Typically, such printed planar inductors  1000  are a geometric spiral-type shape printed on a single plane of the printed circuit board  1100 , as shown in  FIG. 1B . These structures result in a current loop that is parallel to the metallization planes of the Printed Circuit Board substrate. Unfortunately, the series resistance of printed planar inductors  1000  results in a low quality factor as electrical current is converted into heat. Additionally planar inductors  1000  occupy a substantial amount of surface area, limiting their usefulness in high-density applications. 
       SUMMARY 
       [0006]    An apparatus with an inductor having a conductive loop perpendicular to a metalization plane of a substrate. The conductive loop has an upper element and lower element both parallel to the metalization plane that are connected with a via. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0007]      FIGS. 1A and 1B  depict a planar inductor of the PRIOR ART. 
           [0008]      FIG. 2  illustrates three-dimensional printed inductor embodiment. 
           [0009]      FIG. 3  is a diagram of a three-dimensional printed inductor embodiment with a single turn. 
           [0010]      FIG. 4  is a diagram of a three-dimensional printed inductor embodiment with a two turns. 
           [0011]      FIG. 5  is a diagram used to illustrate the calculation of inductance for a three-dimensional printed inductor embodiment constructed with rectangular elements. 
           [0012]      FIG. 6  is a diagram used to illustrate the calculation of inductance for a three-dimensional printed inductor embodiment constructed with tubular elements. 
           [0013]      FIG. 7  is a diagram used to illustrate the calculation of inductance for a three-dimensional printed inductor embodiment constructed with rectangular elements and tubular vias. 
           [0014]      FIG. 8  illustrates a embodiment made up of a pair of coupled three-dimensional printed inductors. 
           [0015]      FIG. 9  illustrates a transformer embodiment made up of two three-dimensional printed inductors. 
           [0016]      FIGS. 10A-B  illustrates a simulation of a pair of single coupled in transmission or isolation. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    One aspect of the present disclosure is the realization that traditional inductors are limited because they have a current loop (also referred interchangeably as a “turn”) formed that is parallel to the metallization planes of a substrate. 
         [0018]    Another aspect of the present disclosure includes the realization that inductors may be fabricated within a printed circuit board in three-dimensions with loops formed perpendicular to metalization planes of a substrate, resulting a high quality factor inductor. 
         [0019]      FIG. 2  conceptually illustrates a three-dimensional printed inductor  2000  embodiment, constructed and operative in accordance with an embodiment of the present disclosure. In this figure, three-dimensional inductor  2000  is an inductor printed with loops formed perpendicular to metalization planes of a substrate. For illustrative purposes, two inductor loops are depicted; it is understood by those practiced in the art that any number of inductor loops may be used in 3D inductor  2000 . The number, size, and area of loops may be adjusted according to the characteristics required from the 3D inductor  2000 . 
         [0020]    It is understood that any substrate may be used, such as a Printed Circuit Board substrate or a semiconductor substrate (including, but not limited to a silicon (Si) or gallium arsenide (GaAs) substrate). For illustrative purposes only, we will describe Printed Circuit Board embodiments. 
         [0021]      FIG. 3  is a diagram of the three-dimensional printed inductor  3000  embodiment, constructed and operative in accordance with an embodiment of the present disclosure. In this figure, three-dimensional inductor  3000  is an inductor printed within printed circuit board  3100 , and the loops are formed perpendicular to metalization planes of the printed circuit board  3100  substrate. For illustrative purposes, a single inductor loop is depicted; it is understood by those practiced in the art that any number of inductor loops may be used in 3D inductor  3000 . An example multi-loop inductor with two turns is depicted in  FIG. 4 , constructed and operative in accordance with an embodiment of the present disclosure. 
         [0022]    Returning to  FIG. 3 , the inductor  3000  itself may be made of any conductive material used in the fabrication of a printed circuit board  3100 . Example conductors include copper, gold, aluminum, or any other conductor known in the art. 
         [0023]    The printed circuit board  3100  may comprise insulating layers of dielectric laminated together with epoxy resin prepreg. The dielectric may be selected upon different insulating values, depending on the requirements of the circuit. Example dielectrics include polytetrafluoroethylene (ex. Teflon™), woven fiberglass with an epoxy resin (ex. FR-1 or FR-4), or composite epoxy material (“CEM”). 
         [0024]    Accordingly, inductor  3000  is printed on multiple layers of the printed circuit board  3100  forming upper and lower parts of a loop. The layers are connected with vias to connect the upper and lower parts to form the loop. 
         [0025]    The inductance of an inductor  3000  embodiment is dependent upon the actual dimensions of the device. As is understood in the art, an electro-magnetic simulator may be used to find the inductance, Q, and self-resonant frequency (SRF). However, empirical equations may be used to approximate inductance calculations for inductor embodiments.  FIGS. 5-7  describe inductance approximations for single loop inductors with a variety of different dimensions. 
         [0026]      FIG. 5  is a diagram used to illustrate the inductance approximation of for a three-dimensional printed inductor embodiment constructed with rectangular elements, constructed and operative in accordance with an embodiment of the present disclosure. In such an embodiment, the inductor may be thought of as made of a single rectangular loop of rectangular wire. The inductance of such a wire may be approximated as: 
         [0000]        L   rect   ≈N   2 μ r μ o   /π{hln (2 h /( a+b ))+ wln (2 w /( a+b ))− wln (( w+d )/ h )− hln (( h+d )/ w )−( w+h )/2+2 d +0.45( a+b )}
 
         [0027]    where 
         [0028]    L rect  is the inductance in nanoHenries, 
         [0029]    N=number of turns (Note that number of turns need not be an integer, but must be close to 1.), 
         [0030]    μ r μ o π=400, 
         [0031]    w, h are width and height of the loop respectively, 
         [0032]    d is the diagonal (calculated as the square root of (w 2 +h 2 )), in meters, and 
         [0033]    a, b are the width and thickness of the rectangular wire, in meters. 
         [0034]      FIG. 6  is a diagram used to illustrate the calculation of inductance for a three-dimensional printed inductor embodiment constructed with tubular elements, constructed and operative in accordance with an embodiment of the present disclosure. In this embodiment, a rectangular inductor is made of a wire with a radius of “r.” The inductance of such a wire may be approximated as: 
         [0000]        L   tubular   ≈N   2 μ r μ o   /π{hln (2 h/r )+ wln (2 w/r )− wln (( w+d )/ h )− hln (( h+d )/w)−2( w+h )+2 d} 
 
         [0035]    L tubular  is the inductance in nanoHenries, 
         [0036]    N=number of turns (Note that number of turns need not be an integer, but must be close to 1.), 
         [0037]    μ r μ o /π=400, 
         [0038]    w, h are width and height of the loop respectively, 
         [0039]    d is the diagonal (calculated as the square root of (w 2 +h 2 )), in meters, and 
         [0040]    r is the radius of the round wire, in meters. 
         [0041]      FIG. 7  is a diagram used to illustrate the calculation of inductance for a three-dimensional printed inductor embodiment constructed with rectangular elements and tubular vias, constructed and operative in accordance with an embodiment of the present disclosure. In this embodiment, a hybrid rectangular inductor is made of rectangular elements connected by vias with a radius of “r.” The inductance of such a wire may be approximated as: 
         [0000]        L   hybrid   ≈N   2 μ r μ o   /π{hln (2 h/r )+ wln (2 w /( a+b ))− wln (( w+d )/ h )− hln (( h+d )/ w )−(2 w+h/ 2)+2 d +0.45( a+b )}
 
         [0042]    L hybrid  is the inductance in nanoHenries, 
         [0043]    N=number of turns (Note that number of turns need not be an integer, but must be close to 1.), 
         [0044]    μ r μ o /π=400, 
         [0045]    w, h are width and height of the loop respectively, 
         [0046]    d is the diagonal (calculated as the square root of (w 2 +h 2 )), in meters, 
         [0047]    a, b are the width and thickness of the rectangular wire, in meters, and 
         [0048]    r is the radius of the round wire, in meters. 
         [0049]    Expanding upon the concepts described in the above, it is understood that three-dimensional printed inductors may be used in a variety of different ways, all fully compliant with the embodiments described herein. For example,  FIG. 8  illustrates a embodiment made up of a pair of coupled three-dimensional printed inductors with loops that are perpendicular to metalization planes of a printed circuit board  8100  substrate, constructed and operative in accordance with an embodiment of the present disclosure. In this figure, a pair of three-dimensional inductors  8001 A and  8001 B is an inductor printed within printed circuit board  8100 . For illustrative purposes, the two coupled inductor loops are depicted; it is understood by those practiced in the art that any number of inductor loops may be used. The number, size, and area of loops may be adjusted according to the characteristics required by the circuit. 
         [0050]    In one aspect of the present disclosure includes the realization that, if a pair of printed inductors can be magnetically coupled, and that their coupling is strong enough, then a high frequency balun and/or transformer can be created.  FIG. 9  illustrates a transformer embodiment made up of two three-dimensional printed inductors ( 9001 A and  9001 B), constructed and operative in accordance with an embodiment of the present disclosure. For illustrative purposes only, inductors  9001 A and  9001 B are single turn inductors; it is understood by those familiar with the art that each of the inductors  9001 A and/or  9001 B may implemented using single or multi-turn inductors with loops that are perpendicular to metalization planes of the substrate. Such an embodiment eliminates the cost of a discrete balun element. Furthermore, depending upon the design of the balun/transformer, there can be an insertion los advantage, given the high Q&#39;s that may be realized. 
         [0051]    In another aspect, magnetic and electric couplings between inductor pairs  9001 A and  9001 B can be constructive or destructive, depending on the winding polarity between the inductors—i.e. whether both inductors are wound in the same direction or in opposite directions. 
         [0052]    Furthermore, simply by reversing the sense of an inductor (which may be done using a switch matrix integrated circuit), it is possible to achieve either transmission or isolation. 
         [0053]    Responses in the two states, for a rudimentary and easy to realizable example (a single coupled inductor pair, Sonnet simulation) is shown at  FIGS. 10A and 10B . 
         [0054]    Embodiments of the three-dimensional inductor allow the implementation of switched filter banks or cascades that, under control of an integrated circuit, may pass or reject signals in any desired frequency band. Furthermore, embodiments also enable: radio-frequency (RF) switches with a very low loss, as there is no series loss element, switches with high linearity and no large RF swings at an integrated circuit switch matrix. 
         [0055]    Finally, the three-dimensional inductor embodiments are easily integrated with printed filter designs. 
         [0056]    The previous description of the embodiments is provided to enable any person skilled in the art to practice the invention. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Thus, the current disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.