Abstract: Disclosed are semi non-magnetic bobbins for use in core reactors, and core reactors that include the semi non-magnetic bobbins. The semi non-magnetic bobbins are made of a non-metallic material and provide core reactors that can withstand high temperatures and at the same time avoid eddy current effects. The disclosed semi non-metallically permeable bobbins also do not adversely affect electrical power quality and save power and can be used to capture harmonics currents. When properly designed and arranged can be used to provide electromagnetic induction heaters using harmonics currents imported from an electrical power system as the working source of heat and provide a zero-cost heating process.

Abstract: In order to create a full variable shunt reactor having two magnetically controllable high-voltage throttles which is compact and at the same time can also provide capacitive reactive power, auxiliary windings are used which are inductively coupled to the high-voltage throttles. The auxiliary windings are connected to at least one capacitively acting component.

Abstract: A reactor including: a coil having a winding portion; a magnetic core that is disposed extending inside and outside the winding portion, and is configured to form a closed magnetic circuit; and a resin mold that includes an inner resin disposed between the winding portion and the magnetic core, and does not cover an outer peripheral face of the winding portion.

Abstract: Arrangement of interleaved secondary windings for power transformers that reduces the thickness of secondary windings and allows to build transformers with an odd number of layers.

Abstract: Three-phase interleaved LLC and CLLC resonant converters, with integrated magnetics, are described. In various examples, the primary sides of the phases in the converters rely upon a half-bridge configuration and include resonant networks coupled to each other in delta-connected or common Y-node configurations. The secondary sides of the phases can rely upon a full-bridge configurations and are coupled in parallel. In one example, the transformers of the phases in the converters are integrated into one magnetic core. By changing the interleaving structure between the primary and secondary windings in the transformers, resonant inductors of the phases can also be integrated into the same magnetic core. A multi-layer PCB can be used as the windings for the integrated magnetics.

Abstract: A coil component includes: a core having an annular shape; a coil wound around the core; and an electrode terminal for mounting the coil component. The electrode terminal is connected to the coil and has a mounting surface. The coil is formed by connecting a plurality of wire members. The electrode terminal has a recessed portion indented toward a back surface on a side opposite to the mounting surface. The wire member of the coil is connected to a back surface of a bottom portion of the recessed portion.

Abstract: A transformer includes a core with a surface, a primary winding with two or more primary winding turns wrapped about the core, and a secondary winding with one and only one secondary winding turn extending about the core. The one and only one secondary winding turn is interleaved among the two or more primary winding turns on the surface of the core to limit magnetic flux leakage along the primary winding and the secondary winding. Power converters and power conversion methods are also described.

Abstract: A continuous coil for an inductive component includes a plurality of turns formed by at least one conductor. The continuous coil is substantially egg-shaped. Other example coils, transformers, etc. are also disclosed.

Abstract: A common mode choke coil comprising a core; a first wire and a second wire wound around the core; a first electrode part and a second electrode part disposed on the core and connected to the first wire; and a third electrode part and a fourth electrode part disposed on the core and connected to the second wire. The common mode choke coil has a self-resonance frequency of 700 MHz or more, and a common mode inductance of 300 nH or less, in a frequency band of 1 MHz or less.

Abstract: For a substrate of a coil component, there are arranged a plurality of through-holes; the pattern-wiring is provided with a loop-shaped portion surrounding the circumference of a center hole which penetrates the substrate a pair of end portions which extend from that loop-shaped portion; and the neighboring two through-holes within the plurality of through-holes penetrate the substrate in a state that at least a part of each of the openings thereof superimpose each of the pair of end portions and is connected electrically with each of the end portions. In addition, the opening of one of the through-holes at one of the end portions within the pair of end portions is provided at a biased position close to the other of the end portions with respect to the center of the one of the end portions in the intersecting-direction.

Abstract: A reactor including: a coil including a winding portion formed by winding a winding wire; and a magnetic core that forms a closed magnetic circuit constituted by an inner core portion located inside the winding portion and an outer core portion located outside the winding portion. The reactor further includes an inner resin portion that fills a gap between the inner circumferential surface of the winding portion and the outer circumferential surface of the inner core portion, and when a side, of the outer core portion, that faces the inner core portion is defined as an inner side, and the opposite side is defined as an outer side, the outer core portion is provided with a through hole that is open to both the inner side and the outer side, and the through hole is filled with a portion of the inner resin portion.

Abstract: A low profile high current composite transformer is disclosed. Some embodiments of the transformer include a first conductive winding having a first start lead, a first finish lead, a first plurality of winding turns, and a first hollow core; a second conductive winding having a second start lead, a second finish lead, a second plurality of turns, and a second hollow core; and a soft magnetic composite compressed surrounding the first and second windings. The soft magnetic composite with distributed gap provides for a near linear saturation curve.

Abstract: Three-phase interleaved LLC and CLLC resonant converters, with integrated magnetics, are described. In various examples, the primary sides of the phases in the converters rely upon a half-bridge configuration and include resonant networks coupled to each other in delta-connected or common Y-node configurations. The secondary sides of the phases can rely upon a full-bridge configurations and are coupled in parallel. In one example, the transformers of the phases in the converters are integrated into one magnetic core. By changing the interleaving structure between the primary and secondary windings in the transformers, resonant inductors of the phases can also be integrated into the same magnetic core. A multi-layer PCB can be used as the windings for the integrated magnetics.

Abstract: Disclosed are induction heating cells comprising tensioning members with non-magnetic metal cores. Also disclosed are methods of operating such cells, for example, to process composite parts. The non-magnetic metal cores of the tensioning members provide excellent tensile strength. Furthermore, the non-magnetic metal cores allow forming long tensioning members leading to large induction heating cells for processing large composite parts, such aircraft fuselage parts, wing parts, and the like. The diameter of these non-magnetic metal cores is less than the induction heating threshold for magnetic fields used during operation of the cells, which ensures limited or no interaction of the cores with the magnetic fields. The cores can be arranged into a tensioning member extending through and compressing the die of an induction heating cell. When multiple cores are used, these cores are electrically insulated from each other, e.g., using an insulating shell or spacing these cores away from each other.

Abstract: A technology capable of setting a leakage inductance to a predetermined value and enabling miniaturization is provided. In a transformer including a primary coil and a secondary coil which are coaxially provided, the primary coil includes a first primary coil portion and a second primary coil portion in series, the secondary coil includes a first secondary coil portion and a second secondary coil portion in series, the second primary coil portion and the second secondary coil portion are provided outside the first primary coil portion and the first secondary coil portion, and a degree of coupling between the second primary coil portion and the second secondary coil portion is set to be lower than a degree of coupling between the first primary coil portion and the first secondary coil portion.

Abstract: A balanced-to-unbalanced (balun) transformer may include two metal layers on a substrate, a first winding following a first winding path, and a second winding following a second winding path, where each winding is formed in one or more of the two metal layers. The winding paths may include winding segments each disposed around a central axis of the balun transformer, where connectors join adjacent winding segments such that the winding paths are continuous between ends of the windings. The second winding path may be interwoven with, but independent from, the first winding path to form a resultant pattern that is substantially symmetrical. The second winding may include a number, n, of sub-windings, where n>1 such that a resultant number of winding segments of the second winding is greater than a resultant number of winding segments of the first winding by a factor of n.

Abstract: A semiconductor element includes a first coil substantially located at a first plane; a second coil substantially located at the first plane; a connecting section that connects the first coil and the second coil; a third coil substantially located at a second plane different from the first plane; and a fourth coil substantially located at the second plane. The third coil and the first coil are connected through a through structure, and the fourth coil and the second coil are connected through a through structure. The third coil and the fourth are not directly connected.

Abstract: Provided is a reactor with enhanced strength. The reactor includes a coil, a magnetic core, an interposed member interposed between the coil and the magnetic core, and a resin mold portion. The interposed member includes a frame portion that has a first through hole, and a plate-shaped portion. The resin mold portion includes an interposed resin portion that is formed by a constituent resin of the resin mold portion being filled inside the first through hole, an inner side resin portion is formed by the constituent resin being filled inside a portion of a coil interior space, and an outer side resin portion. The plate-shaped portion includes an interposed wall portion, and a second through hole that is provided locally in a portion other than the interposed wall portion, and inside of which the constituent resin is filled.

Abstract: An array of rolled-up power inductors for on-chip applications comprises at least two rolled-up power inductors connected in series and formed from a stack of multilayer sheets. The array includes a first rolled-up power inductor comprising a first multilayer sheet in a rolled configuration about a first longitudinal axis and second rolled-up power inductor comprising a second multilayer sheet in a rolled configuration about a second longitudinal axis. The first and second rolled-up power inductors are laterally spaced apart. The first multilayer sheet comprises a first patterned conductive layer on a first strain-relieved layer, and the second multilayer sheet comprises a second patterned conductive layer on a second strain-relieved layer. Prior to roll-up of the second and first multilayer sheets, the second multilayer sheet is disposed on the first multilayer sheet, and a through-thickness first via connects the second patterned conductive layer with the first patterned conductive layer.

Abstract: A transformer includes a magnetic core assembly including a cylindrical bobbin around which transformer windings are wrapped. Primary transformer windings are wrapped around the cylindrical bobbin of the magnetic core assembly with additional primary transformer windings that are extended to come in contact with one or more external surfaces of the magnetic core assembly. Secondary transformer windings are wrapped around the cylindrical bobbin of the magnetic core assembly with additional secondary transformer windings that are extended to come in contact with the one or more external surfaces of the magnetic core assembly.

Abstract: A winding arrangement for inductive components includes a first winding section comprising at least one first winding, the at least one first winding comprising at least two electrically isolated parallel flat band conductors being configured as a first flat band stack, a second winding section comprising at least one second winding, the at least one second winding comprising at least two electrically isolated parallel flat band conductors being configured as a second flat band stack. The first ends of the flat band conductors of the first winding section are cross connected in a cross connection to first ends of the flat band conductors of the second winding section such that a first current flow stacking sequence in the first flat band stack is reversed to a second current flow stacking sequence in the second flat band stack.

Abstract: An electronic component includes a core, a first outer electrode, a second outer electrode, one or more third outer electrodes, and a wire electrically connecting the first outer electrode, the third electrodes, and the second outer electrode in series in that order. The wire forms a first inductor by being wound on the core between the first outer electrode and one of the third electrodes, and also forms a second inductor by being wound on the core between one of the third outer electrodes and the second outer electrode.

Abstract: A transformer comprises a first core, a second core, a plurality of electrodes, an inner winding and an outer winding. The first core has a central hole. The second core is disposed in the central hole. The second core has two flanges and a pillar located between the two flanges. The inner winding is wound around the pillar. A first winding end of the inner winding is electrically connected to one of the electrodes. The inner winding comprises a first wire and a first insulating layer covering the first wire. The outer winding is wound around the inner winding. A second winding end of the outer winding is electrically connected to one of the electrodes. The outer winding comprises a second wire and a second insulating layer covering the second wire. Second thickness of the second insulating layer is larger than first thickness of the first insulating layer.

Abstract: A receiving antenna of a wireless power receiving device wirelessly charging electric power according to an embodiment of the present invention includes a substrate, a first soft magnetic layer stacked on the substrate, and including a soft magnetic material, and a receiving coil configured to receive electromagnetic energy emitted from a wireless power transmission device, and including a first coil layer wound in parallel with the soft magnetic layer, and a second coil layer electrically connected to the first coil layer and wound in parallel with the first coil layer, and a current direction of the first coil layer is opposite to a current direction of the second coil layer.

Abstract: A transformer is capable of suppressing the output voltage difference, and a switched-mode power supply apparatus uses the transformer. A transformer has a core; a primary winding provided in the core; a gap provided in the core at a location where the primary winding is provided; and at least two secondary windings, provided in the core and spaced apart from both sides of the primary winding as well as the gap at an equal distance in a winding axis direction of the primary winding. A switched-mode power supply apparatus has the transformer; a switching element connected to the primary winding of the transformer; and a control circuit configured to control the switching element.

Abstract: A transformer being capable of reducing cross regulation even in a case where the load is unbalanced and a switched-mode power supply apparatus using the transformer are provided. A transformer T has a core; a primary winding provided in the core; at least two secondary windings provided in the core around a winding axis which is the same as a winding axis of the primary winding; and at least two auxiliary windings provided in the core around a winding axis which is the same as the winding axis of the primary winding; respectively neighboring the secondary windings; and connected in parallel to each other. A switched-mode power supply apparatus has the transformer T; a switching element connected to the primary winding of the transformer T; and a control circuit configured to control the switching element.

Abstract: A circuit board (01), including at least two electrically conductive layers (02) arranged one above the other and at least one dielectric layer (03), which is arranged between adjacent electrically conductive layers (02), is provided. The circuit board (01) is characterized in particular in that the plate has at least two magnetically conductive layers (05), wherein each magnetically conductive layer (05) is arranged at least indirectly adjacent to an electrically conductive layer (02), and that the circuit board also has vertical recesses for accommodating magnetic vias (08) for connecting the magnetically conductive layers (05) in a specific manner. A method for producing such a circuit board (01) is provided.

Abstract: For reducing volume requirements and magnetic flux leakage, a compact inductor includes a first planar core with a first core thickness along a first axis orthogonal to a plane of the first planar core. In addition, the inductor includes a second planar core disposed parallel to the first planar core with a second core thickness along the first axis. The inductor further includes a plurality of electrical windings disposed between and adjacent to an inside plane of the first planar core and an inside plane of the second planar core. The electrical windings may include insulated electrical wires. No magnetic teeth may be disposed between the first planar core and the second planar core. The first axis is parallel to a magnetic axis of each electrical winding.

Abstract: A power factor correction (PFC) power converter, particularly of a multiphase totem-pole or other topology presenting a switching bridge that can potentially provide bi-directional power transfer control, reduces a nominal switching frequency and achieves zero voltage switching over an increased portion of a half line cycle by providing positive or inverse coupling of inductors in an inductor structure that can be formed of a multi-layer printed circuit board such that at least three different inductances are presented during each half line cycle period; allowing increased switching frequency and simplifying EMI filtering arrangements. Parasitic capacitances can be balanced with additional coupled windings to reduce differential mode and common mode noise. The PFC power converter is particularly applicable to provide bi-directional power control from an on-board battery charger in an electrically powered vehicle.

Abstract: A transformer being capable of reducing cross regulation even in a case where the load is unbalanced and a switched-mode power supply apparatus using the transformer are provided. A transformer T has a core; a primary winding provided in the core; at least two secondary windings provided in the core around a winding axis which is the same as a winding axis of the primary winding; and at least two auxiliary windings provided in the core around a winding axis which is the same as the winding axis of the primary winding; respectively neighboring the secondary windings; and connected in parallel to each other. A switched-mode power supply apparatus has the transformer T; a switching element connected to the primary winding of the transformer T; and a control circuit configured to control the switching element.

Abstract: A 3D nested transformer includes a substrate having a set of through substrate vias daisy chained together with a set of traces. At least some of the through substrate vias have first and second conductive regions. The set of traces also includes a first set of traces coupling together at least some of the first conductive regions of the through substrate vias, and a second set of traces coupling together at least some of the second conductive regions of the through substrate vias.

Abstract: A first coil element includes a first loop-shaped conductor and a second loop-shaped conductor. A second coil element includes a third loop-shaped conductor and a fourth loop-shaped conductor. The first loop-shaped conductor and the second loop-shaped conductor are sandwiched in a stacking direction between the third loop-shaped conductor and the fourth loop-shaped conductor. A conductive pattern which is a portion of the first loop-shaped conductor and a conductive pattern which is a portion of the second loop-shaped conductor are connected in parallel. Then, each of a conductive pattern which is a remaining portion of the first loop-shaped conductor and a conductive pattern which is a remaining portion of the second loop-shaped conductor is connected in series with the parallel circuit.

Abstract: A receiving antenna of a wireless power receiving device wirelessly charging electric power according to an embodiment of the present invention includes a substrate, a first soft magnetic layer stacked on the substrate, and including a soft magnetic material, and a receiving coil configured to receive electromagnetic energy emitted from a wireless power transmission device, and including a first coil layer wound in parallel with the soft magnetic layer, and a second coil layer electrically connected to the first coil layer and wound in parallel with the first coil layer, and a current direction of the first coil layer is opposite to a current direction of the second coil layer.

Abstract: Integrated circuits and coupled inductors with isotropic magnetic cores, and methods for fabricating integrated circuits and coupled inductors with isotropic magnetic cores are provided. In an embodiment, a coupled inductor includes a first inductor coil arranged around a coil center and a second inductor coil arranged around the coil center. The second inductor coil is interleaved with the first inductor coil, and the first and second inductor coils form an interleaved inductor coil. The coupled inductor further includes an isotropic magnetic core surrounding a portion of the interleaved inductor coil and passing through the coil center.

Abstract: A planar transformer is provided, which comprises a plate-shaped conductor substrate with integrated primary winding, secondary winding and coupling winding. The conductor substrate has pairs of recesses, and a respective two-part ferromagnetic core having yoke legs is inserted through each pair of recesses. One leg of each core is surrounded by the primary winding or the secondary winding, while the coupling winding is looped around the remaining legs of the cores. At least a minimum total isolation separation distance made up of partial isolation separation distances between the coupling winding and adjacent yoke legs or adjacent windings is maintained for electrical isolation between the primary winding and the secondary winding.

Abstract: A transformer includes a primary winding unit, a secondary winding unit and a magnetic core. The primary winding unit includes a first input primary winding part and a first shielding winding part. The first input primary winding part is electrically connected to at least one switch component, and the first input primary winding part is electrically connected to the first shielding winding part. The secondary winding unit is inductively coupled to the primary winding unit, and the first shielding part is disposed between the first input primary winding part and the secondary winding part. Then, the primary winding unit and the secondary winding unit are assembled to the magnetic core.

Abstract: Systems, methods and apparatus for a wireless power transfer are disclosed. In one aspect a wireless power transfer apparatus is provided. The apparatus includes a casing. The apparatus further includes an electrical component housed within the casing. The apparatus further includes a sheath housed within the casing. The apparatus further includes a conductive filament housed within the sheath. The electrical component is electrically connected with the conductive filament. The casing is filled with a settable fluid bound with the sheath to form a structural matrix.

Abstract: Systems, methods and apparatus for a wireless power transfer are disclosed. In one aspect a wireless power transfer apparatus is provided. The apparatus includes a casing. The apparatus further includes an electrical component housed within the casing. The apparatus further includes a sheath housed within the casing. The apparatus further includes a conductive filament housed within the sheath. The electrical component is electrically connected with the conductive filament. The casing is filled with a settable fluid bound with the sheath to form a structural matrix.

Abstract: An inductive wireless power device comprises a transmitter configured to generate an electromagnetic field to a coupling region for wireless power transfer to a receiver, and control logic configured to determine a coupling coefficient of the wireless power transfer when the receiver is within the coupling region. The control logic also determines a presence of a foreign object within the coupling region responsive to a comparison of the determined coupling coefficient and an expected coupling coefficient for the wireless power transfer. An inductive wireless power device comprises a receiver configured to couple with an electromagnetic field in a coupling region for inductive wireless power transfer from a transmitter. The receiver is configured to alter a wireless power transfer characteristic of the transmitter for a determination of a presence of a foreign object within the coupling region responsive to a determination of a coupling coefficient of the wireless power transfer.

Abstract: In one embodiment, an integrated circuit is described. The integrated circuit includes a substrate, a dielectric stack, a first inductor and a second inductor. The dielectric stack may be formed above the substrate and includes first and second layers. The first inductor may be formed in both the first and second layers. The second inductor may also be formed in the first and second layers with a substantial portion of the first inductor structure overlaps with the second inductor structure.

Abstract: A flexible circuit current measuring apparatus includes a flexible substrate member having a top side and a bottom side, a plurality of first conductive traces disposed on the top side of the flexible substrate member and spaced along a length of the flexible substrate member, and a plurality of second conductive traces disposed on the bottom side of the flexible substrate member and spaced along the length of the flexible substrate member. The first conductive traces and the second conducive traces are electrically connected to one another to form a serpentine pattern having a number of windings about and along the flexible substrate member, and the current measuring apparatus is structured to be wrapped around a conductor for measuring a current carried by the conductor.

Abstract: A system for efficiently charging a target device such as a power toothbrush, when placed in a charging receptacle such as a cup connected to a source of electrical power. A plurality of steering coils are arranged around the primary charging coil in the charging receptacle. A control circuit changes the magnetic field phase pattern of the steering coils relative to the phase of magnetic field of the primary coil until the maximum power transfer between the charging receptacle and the target device is determined. Charging of the target device occurs at the maximum power transfer rate.

Abstract: A low cost, reduced form factor, high performance electronic device for use in electronic circuits and methods. In one exemplary embodiment, the device includes a unitary header assembly construction that ensures device coplanarity and also includes vertically oriented terminal pins. The device utilizes preconfigured flat coil windings that are disposed directly within a planar core. The flat coil windings further include features that are configured to mate with the header assembly terminal pins which substantially simplify the manufacturing process. Methods for manufacturing the device are also disclosed.

Abstract: An energy transfer assembly includes first and second windings wound around a bobbin. The first winding has a first number of layers proximate to a first end and a second number of layers proximate to a second end of the bobbin. The second winding has a third number of layers proximate to the first end and a fourth number of layers proximate to the second end. At least a portion of one of the first and second windings overlaps at least a portion of the other one of the first and second windings. A degree of overlap between the first and second windings is non-uniform. An isolation barrier is between the first and second windings and around the bobbin. A distance between the isolation barrier and an axis of the bobbin varies along the length of the bobbin.

Abstract: A current-compensated choke features several current paths and includes several windings that are connected in parallel and wound around a common core. The windings preferably are alternately wound on the core in such a way that windings of a common current path are not arranged directly one on top of another.

Abstract: Rotational intravascular ultrasound (IVUS) imaging devices, systems, and methods are provided. The present disclosure is particularly directed to rotary transformers incorporating flex circuits that are suitable for use in rotational IVUS systems. In one embodiment, a rotary transformer for a rotational IVUS device includes: a rotational component and a stationary component. At least one of the rotational and stationary components includes a core formed of a magnetically conductive material and a flex circuit coupled to the core. In some instances, the flex circuit is coupled to the core such that a coil portion of the flex circuit is received within a recess of the core and an extension of the flex circuit extending from the coil portion extends through an opening of the core.

Abstract: An improved structure of transformer's lead frame includes at least a lead frame module consisting of a lead frame main body and a lead frame cover, the lead frame main body has a through hole furnished at the center thereof; a bobbin formed at the side of the circumference of the through hole, and a pair of oppositely configured and reversely salient extension parts furnished at sides of the circumference of the through hole, each of the extension parts is combined to the mid-section of the wire connecting seats that have a plurality of wire connecting posts, a plurality of clip indentations are furnished at intervals and at the mid-section of the edge of the two sides of the corresponding extension parts and at the positions covered by the width of the corresponding extension parts.

Abstract: An improved structure of transformer includes a lead frame main body (1), a lead frame cover (2), a trouser-like flap (3), and two iron cores (4) where the lead frame main body (1) has a penetration hole (11) with a bobbin (12) formed at the circumference there around. The trouser-like flap (3) being made of metal has a hollow part (31) for slipping on a bobbin (121) of the lead frame main body (1) also includes horizontally stretched thigh parts (32), (33). The outer circumference of the trouser-like flap (3) is furnished with a primary winding (123). The lead frame cover (2) being a sheet-shaped body has a hollow hole (21) furnished at the center thereof. On the inner-side surface, each of the two iron core (4) has a main core part (41) capable of stretching through the penetration hole (11) of the lead frame main body (1) where the main core part (41) has a containing circumferential trench (43) capable of containing the lead frame main body (1).

Abstract: A coil for forming an induced magnetic field may include a first coil bundle formed of a first conducting wire wound in a first direction, the first coil bundle having an inner space of a prescribed inner width, a second coil bundle formed of a second conducting wire wound in a second direction, the second coil bundle having a prescribed outer width that is smaller than the inner width of the first coil bundle, and a connector that electrically connects the first conducting wire and the second conducting wire to each other. The second coil bundle may be provided in the inner space of the first coil bundle. The conducting wires of the first and second coil bundles may be wound in opposite directions and gaps between coil bundles may be changed. Accordingly, the magnetic field can be more evenly distributed in a wider area while maintaining a constant inductance.

Abstract: Various embodiments may provide a monolithic transformer for a radio frequency (RF) power amplifier module, such as a microwave frequency power amplifier module. The transformer may include a plurality of pairs of edge-coupled transmission lines, with individual pairs including first and second edge-coupled transmission lines. The first transmission lines may include first ends coupled with one another and second ends coupled with an input terminal of the transformer. The second transmission lines may include first ends coupled with the input terminal and second ends coupled with an output terminal of the transformer. The transformer may pass a communication signal from the input terminal to the output terminal, and provide a first impedance at the input terminal and a second impedance at the output terminal. The second impedance may be higher than the first impedance (e.g., by a factor of four).