Fully Coupled Magnetic Device

Abstract

The present invention relates to the technical field of coupled inductors, in particular discloses a fully coupled magnetic device, including at least two phases of circuits, with each phase formed by several coupling units connected in series. Every two phases of circuits are directly coupled through at least one coupling unit, and a direction of a magnetic field generated by DC (direct current) of one phase of the two phases of circuits is opposite to that of another phase of the two phases of circuits. The fully coupled magnetic device of the present invention provides direct coupling between any two phases of circuits, which facilitates lower phase current ripple. It has excellent scalability with the highly regular device layout. It is small in size, low in cost, and highly integrated. The device is able to be integrated into a single chip by stacking itself on top of other semiconductor chips. It is also able to be directly built on top of power management integrated circuits (IC) fabricated in advance on a silicon wafer, thereby forming a monolithically integrated power supply, a miniaturized solution with no need of external magnetic devices. The resulting integrated power supplies are able to be applied to replace the traditional discrete-component-based power solutions in a variety of applications.

Claims

1. (canceled)

2. A fully coupled magnetic device, which comprises at least two phases of circuits, wherein each phase of the two phases of circuits comprises multiple coupling units (1) all of which are connected, every two phases of circuits are directly coupled through at least one coupling unit (1), and a direction of a magnetic field generated by DC (direct current) of one phase of the two phases of circuits is opposite to that of another phase of the two phases of circuits; the fully coupled magnetic device further comprises multiple identical coupling units (1) arranged in a matrix of N rows×(N−1) columns, wherein the matrix of the coupling units (1) is denoted as: A=(a.sub.ij).sub.N×(N−1), where a phase number N of the fully coupled magnetic device is an integer number ≥2, a.sub.ij is the coupling unit in the row and j.sup.th column of the matrix A, i=1, 2, 3, . . . N, j=1, 2, 3, . . . N−1; each coupling unit (1) comprises a magnetic core (2), a forward winding coil (3) and a reverse winding coil (4), and the forward and reverse winding coils are wound on the magnetic core (2) or the magnetic core (2) wraps the forward and reverse winding coils, the number of turns of the forward and reverse winding coils is the same, and the magnetic fields in the magnetic core (2) generated by currents in the forward and reverse winding coils are opposite to each other in direction, and all N input terminals are located at one side of the matrix, and all N output terminals are located at the other side of the matrix; when p=1 (p represents phase number and varies from 1 to N), the 1.sup.st phase current starts from the first input terminal, passes sequentially through the forward winding coil (3) within the coupling units of a.sub.11, a.sub.12, a.sub.13, . . . a.sub.1(N−1), and then passes sequentially through the reverse winding coil (4) within the coupling units of a.sub.2(N−1), a.sub.3(N−), a.sub.4(N−3), . . . a.sub.N1, all connected in series until reaching the first output terminal to become the complete 1.sup.st phase circuit; when p=2, 3, 4, . . . N−1, the p.sup.th phase current starts from the p.sup.th input terminal, passes through the reverse winding coil (4) of the coupling units a.sub.1(p−1), a.sub.2(p−2), a.sub.3(p−3), . . . a.sub.(p−1)1, then passes through the forward winding coil (3) of the coupling units a.sub.p1, a.sub.p2, a.sub.p3, . . . a.sub.p(N−1), then passes through the reverse winding coil (4) of the coupling units a.sub.(p+1)(N−1), a.sub.(p+2)(N−2), a.sub.(p+3)(N−3), . . . a.sub.Np, all connected in series until reaching the p.sup.th output terminal to become the p.sup.th phase circuit; when p=N, the N.sup.th phase current starts from the p.sup.th input terminal, passes through the reverse winding coil (4) of the coupling units a.sub.1(p−1), a.sub.2(p−2), a.sub.3(p−3), . . . a.sub.(p−1)1, and then go through the forward winding coil (3) of the coupling units a.sub.p1, a.sub.p2, a.sub.p3, . . . a.sub.p(N−1), all connected in series until reaching the N.sup.th output terminal to become the N.sup.th phase circuit.

3. The fully coupled magnetic device according to claim 2, wherein the forward winding coil (3) and the reverse winding coil (4) are both solenoid coils wound on the magnetic core (2), the magnetic core (2) has a single layer structure which is made from magnetic materials or a laminated structure which is formed by stacking multiple layers of magnetic materials and insulating materials in sequence, the magnetic core (2) has an open loop or a closed loop.

4. The fully coupled magnetic device according to claim 3, wherein the coupling unit (1) adopts sequential multi-layer deposition and integration process, from bottom to top, comprises a bottom conductor layer (5), a magnetic core layer (6) and a top conductor layer (7); there is an insulating layer (8) between two adjacent layers, multiple through holes (9) are provided in the insulating layer (8) for connecting the bottom conductor layer (5) and the top conductor layer (7), the through holes (9) are filled with conductive materials, two layers of conductors form a spiral through the through holes (9) and are wound on the magnetic core layer (6), a conductive path is formed from the input terminal to the output terminal of each phase of circuit.

5. The fully coupled magnetic device according to claim 4, wherein the bottom conductor layer (5), the magnetic core layer (6) and the top conductor layer (7) are all fabricated using conductive material by micro-nano fabrication method, and the insulating layer (8) is fabricated using insulating material by micro-nano fabrication method, the micro-nano fabrication method comprises photolithography, electrochemical deposition, physical vapor deposition, dry etching and wet etching.

6. The fully coupled magnetic device according to claim 2, wherein the forward winding coil (3) and the reverse winding coil (4) are both stripline coils, and the magnetic core (2) comprises an upper layer and a lower layer, the magnetic core (2) wraps around the forward winding coil (3) and the reverse winding coil (4); the magnetic core (2) has a single layer structure which is made from magnetic materials or a laminated structure which is formed by stacking multiple layers of magnetic materials and insulating materials in sequence, the magnetic core (2) has an open loop or a closed loop.

7. The fully coupled magnetic device according to claim 6, wherein the coupling unit (1) adopts sequential multi-layer deposition and integration process, from bottom to top, comprising a bottom magnetic core (10), a bottom conductor layer (11), a top conductor layer (12), and a top magnetic core (13); there is an insulating layer (8) between two adjacent layers; multiple through holes (9) are provided for connecting the top conductor layer (12) and the bottom conductor layer (11); the through holes (9) are filled with conductive materials, and a conductive path is formed from the input terminal to the output terminal of each phase of circuit.

8. The fully coupled magnetic device according to claim 2, wherein there are two magnetic cores (2), each magnetic core (2) comprises a bottom magnetic core (10) and a top magnetic core (13); the forward winding coil (3) and the reverse winding coil (4) are respectively spiral, and the top and bottom magnetic cores are respectively wrapped around both the forward winding coil (3) and the reverse winding coil (4) respectively; the bottom magnetic core (10) and the top magnetic core (13) of the each magnetic core (2) have a single layer structure which is made from magnetic materials or a laminated structure which is formed by stacking multiple layers of magnetic materials and insulating materials in sequence, the bottom magnetic core (10) and the top magnetic core (13) of the each magnetic core (2) have an open loop or a closed loop.

9. The fully coupled magnetic device according to claim 8, wherein the coupling unit (1) adopts sequential multi-layer deposition and integration process, from bottom to top, comprising the bottom magnetic core (10), the lower wire layer (11), the upper wire layer (12) and the top magnetic core (13); there is an insulating layer (8) between two adjacent layers; multiple through holes (9) are provided for connecting the lower wire layer (11) and the upper wire layer (12), and the through holes (9) are filled with conductive materials; both the forward winding coil (3) and the reverse winding coil (4) are in a spiral shape and symmetrical to each other; the forward winding coil (3) and the reverse winding coil (4) are in the opposite spiral direction, the forward and reverse winding coils in the bottom conductor layer are respectively positively connected to the forward and reverse winding coils in the top conductor layer through the through holes (9).

10. The fully coupled magnetic device according to claim 7, wherein the bottom magnetic core (10), the bottom conductor layer (11), the top conductor layer (12) and the top magnetic core (13) are all fabricated using conductive material by micro-nano fabrication method, and the insulating layer is fabricated using insulating material by micro-nano fabrication method, the micro-nano fabrication method comprises photolithography, electrochemical deposition, physical vapor deposition, dry etching and wet etching.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows a schematic diagram of a four-phase step-down switching power supply circuit using traditional coupled inductor technology in the prior art.

[0029] FIG. 2 shows a schematic diagram of a fully coupled four-phase step-down switching power supply circuit according to Embodiment 1 of the present invention.

[0030] FIG. 3 shows the waveform of the first phase output current of the two circuits given in FIG. 1 and FIG. 2.

[0031] FIG. 4a, FIG. 4b and FIG. 4c are the respective schematic diagrams of the matrix of coupling units and their connections for four-phase, three-phase and two-phase fully coupled magnetic devices in Embodiment 2 of the present invention.

[0032] FIG. 5 shows a schematic view of the structure of the three-phase fully coupled magnetic device in FIG. 4b manufactured by sequential multi-layer deposition and integration process.

[0033] FIG. 6 shows a schematic view of the bottom conductor layer in FIG. 5.

[0034] FIG. 7 shows a schematic view of the magnetic core layer in FIG. 5.

[0035] FIG. 8 shows a schematic view of the through holes in FIG. 5.

[0036] FIG. 9 shows a schematic view of the superimposed structure of the bottom conductor layer, the magnetic core layer, and the through holes in FIG. 5.

[0037] FIG. 10 is a schematic view of the top conductor layer in FIG. 5.

[0038] FIGS. 11a, 11b and 11c are the respective schematic diagrams of the matrix of coupling units and their connections for four-phase, three-phase, and two-phase fully coupled magnetic devices in Embodiment 3 of the present invention.

[0039] FIG. 12a, FIG. 12b and FIG. 12c are the respective schematic diagrams of the matrix of coupling units and their connections for four-phase, three-phase, and two-phase fully coupled magnetic devices in Embodiment 4 of the present invention.

[0040] FIG. 13 shows a schematic cross section view of an integrated coupling unit shown in FIGS. 12a, 12b and 12c.

[0041] FIG. 14 shows a schematic top view of the bottom magnetic core of the coupling unit shown in FIG. 13.

[0042] FIG. 15 shows a schematic top view of the bottom conductor layer of the coupling unit shown in FIG. 13.

[0043] FIG. 16 shows a schematic top view of the top conductor layer of the coupling unit shown in FIG. 13.

[0044] FIG. 17 shows a schematic top view of the top layer magnetic core of the coupling unit shown in FIG. 13.

[0045] FIG. 18 shows a schematic top view of the coupling unit shown in FIG. 13.

[0046] FIG. 19 shows a schematic cross section view of a coupling unit in Embodiment 5 of the present invention.

[0047] FIG. 20 shows a schematic top view of a multi-layer integrated coupling unit in Embodiment 6 of the present invention.

[0048] FIG. 21 is a schematic top view of the bottom magnetic core in FIG. 20.

[0049] FIG. 22 is a schematic top view of the bottom conductor layer of the coupling unit in FIG. 20.

[0050] FIG. 23 is a schematic top view of the through holes of the coupling unit in FIG. 20.

[0051] FIG. 24 is a schematic top view of the top conductor layer of the coupling unit in FIG. 20.

[0052] FIG. 25 is a schematic top view of the top layer magnetic core of the coupling unit in FIG. 20.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0053] The present invention will be further described below in conjunction with FIGS. 1-25 and the specific embodiments.

Embodiment 1

[0054] A fully coupled magnetic device comprises at least two phases of circuits, wherein each phase of circuit comprises multiple coupling units 1 all of which are connected, every two phases of circuits are directly coupled through at least one coupling unit 1, and a direction of a magnetic field generated by a DC (direct current) of one phase of the two phases of circuits is opposite to that of another phase of the two phases of circuits.

[0055] As shown in FIG. 2, taking a four-phase step-down switching power supply as an example, which comprises twelve coupling units 1, namely, L1-2, L1-3, L1-4, L2-1, L2-3, L2-4, L3-1, L3-2, L3-4, L4-1, L4-2, and L4-3; the first phase current starts from the 1.sup.st input terminal and flows through L1-2, L1-3, L1-4, L2-1, L3-1, and L4-1 in turn, reaches the 1.sup.st output terminal, forming the first phase current path; the second phase current starts from the 2.sup.nd input terminal and flows through L1-2, L2-3, L2-4, L2-1, L3-2, and L4-2, reaches the 2.sup.nd output terminal, forming the second phase current path; the third phase current starts from the 3.sup.rd input terminal and flows through L1-3, L2-3, L3-4, L3-1, L3-2, and L4-3 in turn, reaches the 3.sup.rd output terminal, forming the third phase current path; the fourth phase current starts from the 4.sup.th input terminal and flows through L1-4, L2-4, L3-4, L4-1, L4-2, and L4-3 in turn, reaches the 4.sup.th output terminal, forming the fourth phase current path. The first phase circuit is directly coupled to the second phase circuit through L1-2 and L2-1, to the third phase circuit through L1-3 and L3-1, and to the fourth phase circuit through L1-4 and L4-1; the second phase circuit is directly coupled to the first phase circuit through L2-1 and L1-2, and to the third phase circuit through L2-3 and L3-2, and to the fourth phase circuit through L2-4 and L4-2; the third phase circuit is directly coupled to the first phase circuit through L3-1 and L1-3, to the second phase circuit through L3-2 and L2-3, and to the fourth phase circuit through L3-4 and L4-3; the fourth phase circuit is directly coupled to the first phase circuit through L4-1 and L1-4, to the second phase circuit through L4-2 and L2-4, and to the third phase circuit through L4-3 and L3-4. There are two coupling units between every two phases to provide direct coupling.

[0056] This device realizes the direct coupling between all phases. Through this coupling mode, each phase of circuit is able to be directly coupled to all other phases in the device. The four-phase step-down switching power supply circuit using traditional inductor technology shown in FIG. 1 is exactly the same as the circuit provided by the present invention shown in FIG. 2. However, due to the application of fully coupled inductance technology, with the total inductance of each phase of circuit and the coupling coefficient of each coupling unit remain unchanged, no matter when power supply phases are fully opened or partially opened, the circuit in FIG. 2 has a lower phase current ripple than that of the circuit shown in FIG. 1.

[0057] If the electrical specifications of the circuit in FIG. 1 and FIG. 2 are as follows: output voltage is 1.8V, output voltage is 0.9V, switching frequency is 30 MHz, output current is 1.35 A, total inductance per phase is 30 nH, coupling coefficient of coupling unit is −0.7, waveforms of the first phase output current of both circuits are shown in FIG. 3. The current ripple ratio of each phase of the multi-phase fully coupled magnetic device is 81.1% of that of the multi-phase neighboring coupled inductor.

[0058] This fully coupled approach uses a matrix of N×(N−1) coupling units. Compared with the N coupling units in FIG. 1, although the number is increased, it has much lower phase current ripples and output current ripples.

Embodiment 2

[0059] A fully coupled magnetic device comprises multiple identical coupling units 1 arranged in a matrix of N rows×(N−1) columns, and the matrix of coupling units is denoted as: A=(a.sub.ij).sub.N×(N−1), wherein a phase number N of the fully coupled magnetic device is an integer number ≥a.sub.ij is the coupling unit 1 in the i.sup.th row and j.sup.th column of the matrix A, i=1, 2, 3, . . . N, j=1, 2, 3, . . . N−1, each coupling unit 1 comprises a magnetic core 2, a forward winding coil 3 and a reverse winding coil 4, and the forward winding coil 3 and the reverse winding coil 4 are wound on the magnetic core 2 or the magnetic core 2 wraps the forward and reverse winding coils, the number of turns of the forward and reverse winding coils is the same, and the magnetic fields in the magnetic core 2 generated by currents in the forward and reverse winding coils are opposite to each other in direction, and all N input terminals are located at one side of the matrix, and all N output terminals are located at the other side of the matrix. When the number p=1 (p represents phase number and varies from 1 to N), the 1.sup.st phase current starts from the first input terminal, passes sequentially through the forward winding coil 3 within the coupling units of a.sub.11, a.sub.12, a.sub.13, . . . a1.sub.(N−1), and then passes sequentially through the reverse winding coil 4 within the coupling units of a.sub.2(N−1), a.sub.3(N−2), a.sub.4(N−3), . . . a.sub.N1, all connected in series until reaching the first output terminal to become the complete 1.sup.st phase; when p=2, 3, 4, . . . N−1, the p.sup.th phase current starts from the p.sup.th input terminal, passes through the reverse winding coil 4 of the coupling units a.sub.1(p−1), a.sub.2(p−2), a.sub.3(p−3), . . . a.sub.(p−1)1, then passes through the forward winding coil 3 of the coupling units a.sub.p1, a.sub.p2, a.sub.p3, . . . a.sub.p(N−31), then passes through the reverse winding coil 4 of the coupling units a.sub.(p+1)(N−1), a.sub.(p+2)(N−2), a.sub.(p+3)(N−3), . . . a.sub.Np, all connected in series until reaching the p.sup.th output terminal to become a phase; when p=N, the N.sup.th current starts from the p.sup.th input terminal, passes through the reverse winding coil 4 of the coupling units a.sub.1(p−1), a.sub.2(p−2), a.sub.3(p−3), . . . a.sub.(p−1)1, and then go through the forward winding coil 3 of the coupling units a.sub.p1, a.sub.p2, a.sub.p3, . . . a.sub.p(N−1), all connected in series until reaching the N.sup.th output terminal to become a phase.

[0060] Among them, the forward winding coil 3 and the reverse winding coil 4 are both solenoid coils, and the magnetic core 2 is an open loop.

[0061] As shown in FIGS. 4a, 4b and 4c, N is 4, 3, and 2 respectively.

[0062] As shown in FIG. 4a, N=4, there are 4×3=12 coupling units, when p=1, the first phase current starts from the 1.sup.st input terminal, passes the forward winding coil 3 of a.sub.11, a.sub.12 and a.sub.13, and then passes the reverse winding coil 4 of a.sub.23, a.sub.32 and a.sub.41, all connected in series until reaching the 1.sup.st output terminal; when p=2, a.sub.2(p−2) and a.sub.3(p−3) do not exist, so the second phase current starts from the 2.sup.nd input terminal, passes through the reverse winding coil 4 of a.sub.11, then passes the forward winding coil 3 of a.sub.21, a.sub.22 and a.sub.23, and then passes the reverse winding coil 4 of a.sub.33 and a.sub.42, and reaches the 2.sup.nd output terminal in series. Similarly, when p=3, the third phase current starts from the 3.sup.rd input terminal, passes through the reverse winding coil 4 of a.sub.12 and a.sub.21, then passes through the forward winding coil 3 of a.sub.31, a.sub.32 and a.sub.33, and then passes through the reverse winding coil 4 of a.sub.43, and reaches the 3.sup.rd output terminal in series; when p=4, the fourth phase current starts from the 4.sup.th input terminal, passes through the reverse winding coil 4 of a.sub.13, a.sub.22 and a.sub.31, and then passes the forward winding coil 3 of a.sub.41, a.sub.42, a.sub.43, and reaches the 4.sup.th output terminal in series.

[0063] The twelve coupling units are a.sub.11, a.sub.12, a.sub.13, a.sub.21, a.sub.22, a.sub.23, a.sub.31, a.sub.32, a.sub.33, a.sub.41, a.sub.42, a.sub.43, wherein a.sub.11 and a.sub.23 provide the coupling between the first phase circuit and the second phase circuit at the same time; a.sub.12 and a.sub.32 provide the coupling between the first phase circuit and the third phase circuit at the same time; a.sub.13 and a.sub.41 provide the coupling between the first phase circuit and the fourth phase circuit at the same time; and a.sub.21 and a.sub.33 provide the coupling between the second phase circuit and the third phase circuit at the same time; a.sub.22 and a.sub.42 provide the coupling between the second phase circuit and the fourth phase circuit at the same time; a.sub.31 and a.sub.43 provide the coupling between the third phase circuit and the fourth phase circuit at the same time, so as to realize the direct coupling between every two phases of circuits of the four-phase fully coupled magnetic device.

[0064] As shown in FIG. 4b, N=3, there are 3×2=6 coupling units. When p=1, the first phase current passes through the forward winding coil 3 of a.sub.11 and a.sub.12 from the 1.sup.st input terminal, and then passes through the reverse winding coil 4 of a.sub.22 and a.sub.31, reaches the 1.sup.st output terminal; when p=2, the second phase current passes through the reverse winding coil 4 of a.sub.11 from the 2.sup.nd input terminal, and then passes the forward winding coil 3 of a.sub.21 and a.sub.22, then passes through the reverse winding coil 4 of a.sub.32, reaches the 2.sup.nd output terminal. Similarly, when p=3, the third phase current passes through the reverse winding coil 4 of a.sub.12 and a.sub.21 from the 3.sup.rd input terminal, and then through the forward winding coil 3 of a.sub.31 and a.sub.32, reaches the 3.sup.rd output terminal.

[0065] The six coupling units are a.sub.11, a.sub.12, a.sub.21, a.sub.22, a.sub.31 and a.sub.32, wherein a.sub.11 and a.sub.22 provide the coupling between the first phase and the second phase at the same time, a.sub.12 and a.sub.31 provide the coupling between the first phase and the third phase at the same time, a.sub.21 and a.sub.32 provide the coupling between the second phase and the third phase at the same time, so as to realize the direct coupling between every two phases of circuits of the three-phase fully coupled magnetic device.

[0066] As shown in FIG. 4c, N=2, there are 2×1=2 coupling units, when p=1, the first phase current passes through the forward winding coil 3 of a.sub.11 from the first input terminal, and then passes through the reverse winding coil 4 of a.sub.21, and is connected in series to the 1.sup.st output terminal; when p=2, the second phase current passes through the reverse winding coil 4 of a.sub.11 from the second input terminal, and then goes in series through the forward winding coil 3 of a.sub.21 to the 2.sup.nd output terminal.

[0067] The two coupling units are a.sub.11 and a.sub.21 wherein a.sub.11 and a.sub.21 provide the coupling between the first phase circuit and the second phase circuit at the same time, so as to realize the coupling between the two phases of circuits of the two-phase fully coupled magnetic device.

[0068] As shown in FIGS. 5-10, the coupling unit 1 of the three-phase coupled magnetic device shown in FIG. 5 is integrated by sequential multi-layer deposition process, which comprises a bottom conductor layer 5, a magnetic core layer 6, and a top conductor layer 7 from bottom to top. There is an insulating layer 8 between two adjacent layers (not shown in the drawings). Multiple through holes 9 are provided in the insulating layer 8 for connecting the bottom conductor layer 5 and the top conductor layer 7. The through holes 9 are filled with conductive materials. Two layers of conductors are wound on the magnetic core layer 6 through the through holes 9 and form a conductive path from the input terminal to the output terminals of each phase circuit.

[0069] FIGS. 6-10 are schematic views of the bottom conductor layer 5, the magnetic core layer 6, the through hole 9 and the top conductor layer 7 shown in FIG. 5, respectively. FIG. 9 is a schematic view of a superimposed structure of the bottom conductor layer 5, the magnetic core layer 6, and the through holes 9.

[0070] The six magnetic cores 2 in FIG. 7 respectively correspond to the six coupling units 1 arranged in a 3×2 matrix for a three-phase fully coupled magnetic device.

[0071] The bottom conductor layer 5, the magnetic core layer 6 and the top conductor layer 7 are all fabricated using micro-nano fabrication processes comprising photolithography, electrochemical deposition, physical vapor deposition, dry etching and wet etching.

[0072] The magnetic core 2 may be laminated, and formed by sequentially stacking multiple layers of magnetic core materials and insulating materials.

Embodiment 3

[0073] FIGS. 11a, 11b and 11c are the respective schematic diagrams of the matrix of coupling units and their connections for four-phase, three-phase and two-phase fully coupled magnetic devices. All parts are similar to those in embodiment 2, except for the magnetic core 2 in FIGS. 11a, 11b and 11c is a closed loop, which is able to form a closed magnetic flux loop to increase the inductance density.

Embodiment 4

[0074] FIG. 12a, FIG. 12b, and FIG. 12c are the respective schematic diagrams of the matrix of coupling units and their connections for four-phase, three-phase, and two-phase fully coupled magnetic devices. The devices are similar to those in Embodiment 2. The difference between Embodiment 4 and Embodiment 2 is: both the forward winding coil 3 and the reverse winding coil 4 are stripline coils; the magnetic core 2 has top and bottom layers, the magnetic core 2 wraps around the forward winding coil 3 and the reverse winding coil 4, and the top and bottom layers of the magnetic core 2 are in planar shape which doesn't form a closed loop.

[0075] FIG. 13 shows a schematic cross section view of an integrated coupling unit shown in FIGS. 12a, 12b, and 12c. FIG. 14 to FIG. 17 are schematic top views of the bottom magnetic core layer 10, the bottom conductor layer 11, the top conductor layer 12, and the top magnetic core layer 13 of the coupling unit shown in FIG. 13, respectively. FIG. 18 shows a schematic top view of the coupling unit shown in FIG. 13.

[0076] As shown in FIGS. 13-18, the coupling unit 1 is integrated by sequential multi-layer deposition, from bottom to top including a bottom magnetic core layer 10, a bottom conductor layer 11, a top conductor layer 12, a top magnetic core layer 13. There is an insulating layer 8 between two adjacent layers. Through holes 9 (not shown in the drawings) for connecting the bottom conductor layer 11 with the top conductor layer 12. The through holes 9 are filled with conductive materials. A conductive path is formed between the input and the output terminals through the bottom conductor layer 11, the top conductor layer 12 and the through holes 9.

Embodiment 5

[0077] All parts in Embodiment 5 are similar to those in Embodiment 4, except for the magnetic core 2. As shown in FIG. 19, the bottom magnetic core layer 10 and the top magnetic core layer 13 are connected to form a closed loop to increase the inductance density, while the bottom magnetic core layer 10 and the top magnetic core layer 13 are not connected in Embodiment 4.

Embodiment 6

[0078] All parts and connections in Embodiment 6 are similar to those in Embodiment 2, except for the structure of the coupling unit:

[0079] FIG. 20 shows a schematic top view of a multi-layer integrated coupling unit in Embodiment 6. FIG. 21 to FIG. 25 are the respective schematic top views of the bottom magnetic core layer 10, the bottom conductor layer 11, the through holes 9, the top conductor layer 12 and the top magnetic core layer 13 of the coupling unit in Embodiment 6.

[0080] As shown in FIG. 20 to FIG. 25, the coupling unit 1 comprises two magnetic cores 2. Each magnetic core 2 comprises a bottom magnetic core layer 10 and a top magnetic core layer 13. The forward winding coil 3 and the reverse winding coil 4 are in spiral shape. The two magnetic cores (2) respectively wrap the forward winding coil 3 and the reverse winding coil 4. The bottom magnetic core layer 10 and the top magnetic core layer 13 of each magnetic core 2 forms an open loop.

[0081] The coupling unit 1 is integrated by sequential multi-layer deposition process, from bottom to top comprising the bottom magnetic core layer 10, the bottom conductor layer 11, the top conductor layer 12 and the top magnetic core layer 13. There is an insulating layer 8 between two adjacent layers, and the through holes 9 are filled with conductive materials to provide connections between the bottom conductor layer 11 and the top conductor layer 12. Both the forward winding coils 3 and reverse winding coils 4 are in a spiral shape and symmetrical to each other. The forward winding coils 3 and the reverse winding coil 4 are interleaved in both conductor layers with opposite spiral direction; the forward and reverse winding coils in the bottom conductor layer are respectively connected to the forward and reverse winding coils in the top conductor layer through the through holes 9 in a positive manner. The forward winding coils 3 and the reverse winding coil 4 are wrapped up by a pair of magnetic cores 2.

[0082] The above are only preferred embodiments of the present invention; the examples, however, are not exhaustive of the many possible embodiments of the disclosure. All changes and modifications made in accordance with the content of the disclosure should fall within the technical scope of the present invention.