TW201604903A - Integrated transformer - Google Patents

Abstract

An integrated transformer includes a primary inductor and a secondary inductor. The primary inductor includes an B turns spiral wiring formed by a first metal layer and a A turns wiring formed by a second metal layer, where the A turns wiring formed by the second metal layer is stacked on most inner A turns of the B turns spiral wiring formed by the first metal layer. The secondary inductor includes a C turns wiring formed by the second metal layer, where the K turns wiring formed by the second metal layer is stacked on a portion of the B turns spiral wiring formed by the first metal layer of the primary inductor, where A is not greater than B, and A is not greater than C.

Description

Integrated transformer

The present invention relates to an integrated transformer, and more particularly to an asymmetric integrated transformer.

Transformers and baluns are important components in RF integrated circuits for single-ended-to-differential signal conversion, signal coupling, impedance matching, etc., with integrated circuits to the system level. Development of a system on chip (SoC), integrated transformers/baluns have gradually replaced traditional discrete components and are widely used in RF integrated circuits. However, passive components in integrated circuits, such as inductors and transformers, tend to consume a large amount of wafer area, so how to simplify the number of passive components in the integrated circuit and minimize the area of the passive components while optimizing Component characteristics, such as quality factor (Q) and coupling coefficient (K), are an important issue.

Accordingly, it is an object of the present invention to provide an integrated transformer having a good quality factor and coupling coefficient which can be realized with only a small wafer area to reduce the manufacturing cost of the wafer and optimize its components. characteristic.

According to an embodiment of the invention, an integrated transformer includes a first inductor and a second inductor, wherein the first inductor includes a B-circle spiral winding formed by a first metal layer and a second metal The A-ring winding formed by the layer, wherein the A-ring winding formed by the second metal layer substantially overlaps with the innermost A-ring winding of the B-circle spiral winding formed by the first metal layer; The second inductor includes a C-turn winding formed by at least the second metal layer, wherein the second inductor The C-turn winding formed by the second metal layer substantially overlaps a partial winding of the first inductor formed by the first metal layer, wherein A is greater than or equal to B, and A is greater than or equal to C.

110, 120, 125, 130, 210, 220, 225, 230‧‧‧ spiral winding

117, 118, 126, 127, 128, 129_1, 129_2, 136, 137, 138, 139_1, 139_2, 214, 217, 218, 224_1, 224_2, 226, 227, 228, 229_1, 229_2, 234_1, 234_2, 236, 237, 238, 239_1, 239_2‧‧‧ through holes

121_1, 121_2, 221_1, 221_2‧‧‧ input end of the first inductor

122_1, 122_2, 222_1, 222_2‧‧‧ input terminals of the second inductor

132, 133, 232, 233, 242, 243‧‧ ‧ bridge wiring

245, 246‧‧‧ center tap winding

IND1‧‧‧first inductor

IND2‧‧‧second inductance

Fig. 1A is a view showing a first metal layer of the integrated transformer according to the first embodiment of the present invention.

Fig. 1B is a view showing a second metal layer of the integrated transformer according to the first embodiment of the present invention.

Fig. 1C is a view showing a pattern of a third metal layer of the integrated transformer according to the first embodiment of the present invention.

Fig. 1D is a top view of the integrated transformer according to the first embodiment of the present invention.

Fig. 1E is a schematic cross-sectional view showing an integrated transformer according to a first embodiment of the present invention.

Fig. 2A is a view showing a first metal layer of the integrated transformer according to the second embodiment of the present invention.

Fig. 2B is a view showing the second metal layer of the integrated transformer according to the second embodiment of the present invention.

Fig. 2C is a view showing the third metal layer and the fourth metal layer of the integrated transformer according to the second embodiment of the present invention.

Fig. 2D is a top view of the integrated transformer according to the second embodiment of the present invention.

Fig. 2E is a schematic cross-sectional view showing the integrated transformer according to the second embodiment of the present invention.

Fig. 3 is a schematic view showing an integrated transformer according to another embodiment of the present invention.

Fig. 4 is a schematic view showing an integrated transformer according to another embodiment of the present invention.

Fig. 5 is a schematic view showing an integrated transformer according to another embodiment of the present invention.

Figure 6 is a schematic view of an integrated transformer according to another embodiment of the present invention.

Please refer to FIG. 1A, FIG. 1B, FIG. 1C, FIG. 1D and FIG. 1E, wherein FIGS. 1A, 1B and 1C are the first metal layer and the second layer of the integrated transformer according to the first embodiment of the present invention. The pattern of the metal layer and the third metal layer, FIG. 1D is a top view of the integrated transformer according to the first embodiment of the present invention, and FIG. 1E is a cross-sectional view of the embodiment. The integrated transformer of this embodiment can be applied to a transformer in a radio frequency chip or a balanced/unbalanced transformer (balun).

In this embodiment, the integrated transformer is an asymmetric integrated transformer, and the ratio of the inductance values of the two inductors is about 9nH: 6nH (nano-Henry) (for illustrative purposes only, not according to the invention) Limit), and the entire integrated transformer has a small wafer area of approximately 150 um * 100 um (micro-meter).

In this embodiment, the first metal layer is a Re-Distribution Layer (RDL), and the second metal layer is an ultra-thick metal layer (UTM), and the second metal layer is Between the first metal layer and the third metal layer, but the invention is not limited thereto. In other embodiments, the first metal layer and the second metal layer may be adjacent to any two of the integrated circuits. Metal layer.

Please refer to FIG. 1A, FIG. 1B and FIG. 1C first. The integrated transformer mainly comprises a first metal layer, a second metal layer and a third metal layer to form a first inductor and a second inductor, wherein the first inductor It is electrically insulated from the second inductor. The illustrated pattern of the first metal layer includes a spiral wiring 110 and two through holes 117, 118, and in this embodiment, the spiral winding 110 has about 8 to 9 turns; The pattern of the metal layer includes two input terminals 121_1, 121_2 of the first inductor, two input terminals 122_1, 122_2 of the second inductor, spiral windings 120, 125, and a plurality of through holes 126, 127, 128. 129_1, 129_2; the third metal layer comprises a spiral winding 130, a plurality of bridge wires 132, 133, and a plurality of through holes 136, 137, 138, 139_1, 139_2. The through holes in the 1A, 1B, and 1C are used to electrically connect two different metal layers. For example, the through holes 118 of the first metal layer are electrically connected to the second metal layer. The hole 128 and the through hole 129_1 of the second metal layer are electrically connected to the through hole 139_1 of the third metal layer.

In this embodiment, the first inductor includes a B-circle spiral winding 110 composed of a first metal layer and an A-ring spiral winding 120 composed of a second metal layer, at 1A, 1B. In the example shown in the figure, B is about 8 to 9, and A is about 1 to 2. In detail, the two input terminals 121_1, 121_2 of the first inductor are both in the second metal layer, and the spiral winding 110 composed of the first metal layer and the spiral winding formed by the second metal layer The wires 120 are connected in series by the through holes 118, 128 to constitute a first inductance. In addition, in the present embodiment, the first inductor includes only two sets of through holes 117, 127, and 118, 128.

In addition, in the embodiment, the second inductor includes a C-circle spiral winding 125 composed of a second metal layer and a P-circle spiral winding formed by the third metal layer, in the first B, 1C In the example shown, C is about 4 to 5 and P is about 2. In detail, the two input terminals 122_1, 122_2 of the second inductor are all in the second metal layer, the input terminal 122_2 is directly connected to the spiral winding 125, and the spiral winding 125 is formed by the second metal layer. The spiral winding 130 composed of the third metal layer is connected in series by the through holes 129_1, 139_1, and the spiral winding 130 passes through a bridge wire between the through holes 137, 138 (using the fourth metal layer (not Illustrated)) to connect to the bridge wire 133 and the input terminal 122_1, thus forming a second inductance.

Referring to the top view shown in FIG. 1D again, in the first inductor, the innermost winding of the spiral winding 120 formed by the second metal layer and the spiral winding 110 formed by the first metal layer. The lines substantially overlap; and in the second inductor, the spiral winding 125 formed by the second metal layer substantially overlaps with the partial winding of the first inductor formed by the first metal layer, and the second inductor The innermost winding is adjacent to the outermost winding of the helical winding 120 of the first inductor formed by the second metal layer.

In the A-A' section shown in Figs. 1D and 1E, "IND1" indicates the first inductance, and "IND2" indicates the second inductance, which is the innermost two turns of the A-A' section. The first inductor itself forms a structure of a helical stack, and a mutual inductance between the two inductors of the “L” type is also formed between the first inductor and the second inductor, and thus, Improve integrated transformer The quality factor (Q value), as well as increasing the amount of coupling, reduces the area of use. That is, the mutual inductance of the first inductor and the second inductor simultaneously include a short-distance vertical coupling, an oblique coupling, and a horizontal coupling; in other words, the first inductor and the second inductor are coupled by a vertical coupling, an oblique coupling, and a horizontal Coupled to form mutual inductance.

In the integrated transformer described in the above embodiments, since the first inductor and the second inductor themselves use two spiral windings of different metal layers in series, the first inductor can be made with a minimum wafer area. In addition, the integrated inductor of the present embodiment has a good performance in terms of quality factor and coupling amount, so that the manufacturing cost of the wafer can be reduced and the component characteristics can be optimized.

The partial design of the integrated transformer shown in FIGS. 1A to 1E is merely an illustrative example, and is not intended to be a limitation of the present invention. In detail, the illustrated helical windings 120, 130 may not necessarily be helically wound. The line, and the number of turns of the first inductor and the second inductor may also vary according to actual needs. In addition, the spiral winding 130 in FIG. 1C is mainly used to provide an additional inductance value and a coupling amount of the second inductor. In another embodiment of the present invention, the spiral winding 130 in FIG. 1C may be Removed from the integrated transformer.

It should be noted that although in the embodiments shown in FIGS. 1A to 1E, the first inductor and the second inductor do not include any parallel structure, however, sometimes for other considerations, such as improving quality factors, Alternatively, when there are other spaces available in the integrated circuit, other one or more metal layers may be used to additionally form a stacked structure, for example, using a third metal layer or other metal layers to form a plurality of segments. Parallel to the partial windings of the first or second inductor, these design variations are all within the scope of the present invention.

Please refer to FIG. 2A, FIG. 2B, FIG. 2C, FIG. 2D and FIG. 2E, wherein 2A, 2B, and 2C are drawings of a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer of the integrated transformer according to the second embodiment of the present invention, and FIG. 2D is a diagram according to the present invention. A top view of the integrated transformer of an embodiment, and Fig. 2E is a cross-sectional view of the embodiment. The integrated transformer of this embodiment can be applied to a transformer in a radio frequency chip or a balanced/unbalanced transformer.

In this embodiment, the integrated transformer is an asymmetric integrated transformer, and the ratio of the inductance values of the two inductors is about 9nH: 6nH (for illustrative purposes only, not the limitation of the present invention), and the entire integrated transformer has a very large The small wafer area is about 150um*100um.

In this embodiment, the first metal layer is a redistribution process (RDL), and the second metal layer is an ultra-thick metal layer (UTM), and the first metal layer and the second metal are sequentially arranged from top to bottom. a layer, a third metal layer, and a fourth metal layer, but the invention is not limited thereto. In other embodiments, the first metal layer and the second metal layer may be any two adjacent metals in the integrated circuit. Floor.

Please refer to FIG. 2A, FIG. 2B and FIG. 2C first. The integrated transformer mainly comprises a first metal layer, a second metal layer, a third metal layer and a fourth metal layer to form a first inductor and a second inductor. The first inductor itself is electrically insulated from the second inductor. The illustrated pattern of the first metal layer includes a spiral wiring 210 and two through holes 217, 218, and in this embodiment, the spiral winding 210 has about 8 to 9 turns; The pattern of the metal layer includes two input terminals 221_1, 221_2 of the first inductor, two input terminals 222_1, 222_2 of the second inductor, a spiral winding 220, 225, and a plurality of through holes 224_1, 224_2, 226 227, 228, 229_1, 229_2; the third metal layer comprises a spiral winding 230, a plurality of bridge wires 232, 233, and a plurality of through holes 234_1, 234_2, 236, 237, 238, 239_1, 239_2; The four metal layers include a plurality of bridge wires 242, 243, and two center tap windings 245, 246. The through holes in the 2A, 2B, and 2C are used to electrically connect two different metal layers. For example, the through holes 218 of the first metal layer are electrically connected to the second metal layer. Hole 228, while the second metal layer The through hole 229_1 is electrically connected to the through hole 239_1 of the third metal layer.

In this embodiment, the first inductor includes a B-circle spiral winding 210 composed of a first metal layer and an A-ring spiral winding 220 composed of a second metal layer, in the second and second B-layers. In the example shown, B is about 8-9, and A is about 1-2. In detail, the two input terminals 221_1, 221_2 of the first inductor are both in the second metal layer, and the spiral winding 210 composed of the first metal layer and the spiral winding formed by the second metal layer The wires 220 are connected in series by the through holes 218, 228 to constitute a first inductance.

In addition, in the embodiment, the second inductor includes a C-circle spiral winding 225 composed of a second metal layer and a P-ring spiral winding composed of a third metal layer, in the 2B, 2C diagram. In the example shown, C is about 4 to 5 and P is about 2. In detail, the two input terminals 222_1, 222_2 of the second inductor are all in the second metal layer, the input terminal 222_2 is directly connected to the spiral winding 225, and the spiral winding 225 is formed by the second metal layer. The spiral winding 230 composed of the third metal layer is connected in series by the through holes 229_1, 239_1, and the spiral winding 230 passes through the bridge 243 between the through holes 237, 238 to be connected to the bridge 233 and The terminal 222_1 is input to form a second inductance.

The center tap winding 245 is connected to the winding center point of the first inductor through the through holes 234_1, 224_1, 214, and the center tap winding 245 is used to connect to a fixed voltage, such as a supply voltage or a ground voltage, so that the first The center point of the winding of an inductor is maintained at the fixed voltage; in addition, the center tap winding 246 is connected to the center point of the winding of the second store through the through holes 234_1, 224_2, and the center tap winding 246 is also used to connect to A fixed voltage, such as a supply voltage or a ground voltage, is maintained such that the winding center point of the second inductor is maintained at the fixed voltage.

Then please refer to the top view shown in Figure 2D, in the first inductor, by the second gold The spiral winding 220 formed by the genus layer substantially overlaps the innermost winding of the spiral winding 210 formed by the first metal layer; and in the second inductance, the spiral formed by the second metal layer The winding 225 substantially overlaps a partial winding of the first inductor formed by the first metal layer, and the innermost winding of the second inductor is adjacent to the spiral of the first inductor formed by the second metal layer The outermost circumference of the winding 220 is wound.

In the A-A' section shown in Figs. 2D and 2E, "IND1" indicates the first inductance, and "IND2" indicates the second inductance, which is the innermost two turns of the A-A' section. The first inductor itself forms a structure of a helical stack, and a mutual inductance between the two inductors of the “L” type is also formed between the first inductor and the second inductor, and thus, Improve the quality factor (Q value) of the integrated transformer, increase the coupling amount, and reduce the use area. That is, the mutual inductance of the first inductor and the second inductor simultaneously include a short-distance vertical coupling, an oblique coupling, and a horizontal coupling; in other words, the first inductor and the second inductor are coupled by a vertical coupling, an oblique coupling, and a horizontal Coupled to form mutual inductance.

In the integrated transformer described in the above embodiments, since the first inductor and the second inductor themselves use two spiral windings of different metal layers in series, the first inductor can be made with a minimum wafer area. In addition, the integrated inductor of the present embodiment has a good performance in terms of quality factor and coupling amount, so that the manufacturing cost of the wafer can be reduced and the component characteristics can be optimized.

The partial design of the integrated transformer shown in FIGS. 2A-2E is merely an illustrative example, and is not intended to be a limitation of the present invention. In detail, the illustrated helical windings 220, 230 may not necessarily be helically wound. The line, and the number of turns of the first inductor and the second inductor may also vary according to actual needs. In addition, the spiral winding 230 in FIG. 2C is mainly used to provide an additional inductance value and a coupling amount of the second inductor. In another embodiment of the present invention, the spiral winding 230 in FIG. 2C may be Removed from the integrated transformer.

It should be noted that, in the embodiments shown in FIGS. 2A-2E, the first inductor and the second inductor do not include any parallel structure, however, sometimes for other considerations, such as improving quality factors, Alternatively, when there are other spaces available in the integrated circuit, other one or more metal layers may be used to additionally form a stacked structure, for example, using a third metal layer or other metal layers to form a plurality of segments. Parallel to the partial windings of the first or second inductor, these design variations are all within the scope of the present invention.

In addition, in the embodiments of FIGS. 1A to 1D and 2A to 2D, the shape of the inductor winding is square. However, in other embodiments of the present invention, the shape of the inductor winding may be hexagonal, octagonal, or the like. Different shapes, or circular, these design variations are subject to the scope of the present invention.

Please refer to FIG. 3 to FIG. 6 , which are schematic diagrams showing other embodiments of the integrated transformer of the present invention. In detail, in the embodiment shown in FIG. 3, the two-layer spiral stack structure of the first inductor of the inner ring in FIG. 1E and FIG. 2E is modified into a three-layer spiral stack structure, that is, the first inductor. Further, a winding composed of a third metal layer is included, and the winding is connected in series with the spiral windings 110, 120 in FIGS. 1A to 1E; in the embodiment shown in FIG. 4, The two-layer spiral stack structure of the first inductor of the inner ring in FIG. 1E and FIG. 2E is modified into a three-layer spiral stack structure, and the second inductor also has a two-layer spiral stack structure (using the second metal layer and the third metal layer) ), that is, the second inductor further comprises a C-coil spiral winding formed by the third metal layer, and the C-coil winding of the second inductor formed by the second metal layer and the third metal layer The C-circle spiral windings substantially overlap; in the embodiment shown in FIG. 5, a spiral stack structure of a second inductor is additionally added to the outermost circumference of the integrated transformer (using the first metal layer and a second metal layer); in the embodiment shown in Fig. 6, the outermost ring of the integrated transformer is additionally A first metal layer to prepare a wire to be connected to a second inductor. Since those with ordinary knowledge in the field should be able to read the 1A~1E, 2A~2E diagrams After the embodiment, it is understood how to implement the embodiments shown in FIG. 3 to FIG. 6, and the related details are not described herein. Additionally, the present invention may also use process techniques on a 3D stack. For example: IND1 is in the first die (DIE) and IND2 is on the second die (DIE)

Briefly summarized in the present invention, in the integrated transformer of the present invention, the first inductor itself uses a spiral winding in which the first and second metal layers are connected in series, and the second inductor is also formed using at least the second metal layer. The spiral winding, therefore, can make the first inductance and the second inductance have the largest inductance value under the minimum wafer area. In addition, the integrated transformer of the embodiment also has a good performance in the quality factor and the coupling amount. Therefore, the manufacturing cost of the wafer can be reduced and the component characteristics can be optimized.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

IND1‧‧‧first inductor

IND2‧‧‧second inductance

Claims (14)

An integrated transformer comprising: a first inductor comprising a B-circle helical winding formed by a first metal layer and an A-ring winding formed by a second metal layer, wherein the second The A-ring winding formed by the metal layer substantially overlaps with the innermost A-ring winding of the B-circle spiral winding formed by the first metal layer; and a second inductance including at least the second metal a C-ring winding formed by the layer, wherein the C-coil winding of the second inductor formed by the second metal layer substantially overlaps with the partial winding of the first inductor formed by the first metal layer; Where A is greater than or equal to B, and A is greater than or equal to C. The integrated transformer of claim 1, wherein the A-ring winding formed by the second metal layer is also a spiral winding, and the B-circle spiral winding formed by the first metal layer The A-ring winding formed by the second metal layer is connected in series through a through hole to constitute the first inductor. The integrated transformer of claim 1, wherein the innermost winding of the second inductor is adjacent to the outermost winding of the A-ring winding formed by the second metal layer of the first inductor. line. The integrated transformer of claim 1, wherein the second inductor further comprises a plurality of segments formed by a third metal layer, wherein the plurality of segments are used as the second inductor a C-wire wound bridge formed by the second metal layer, and the second metal layer is located between the first metal layer and the third metal layer. The integrated transformer of claim 1, wherein the second inductor further comprises a plurality of segments formed by a third metal layer, wherein the plurality of segments are used in parallel with a portion of the C-coil winding of the second inductor formed by the second metal layer, and the A second metal layer is between the first metal layer and the third metal layer. The integrated transformer of claim 1, wherein the second inductor further comprises a P-ring winding formed by a third metal layer, and the second inductor is composed of the third metal layer. The P-circle winding substantially overlaps the partial winding of the first inductor formed by the second metal layer. The integrated transformer of claim 6, wherein the second inductor has a P-turn winding formed by the third metal layer and a C-turn formed by the second metal layer of the first inductor. The windings substantially overlap. The integrated transformer of claim 6, wherein the P-circle of the third metal layer is also a spiral winding, and the C-coil spiral winding is formed by the second metal layer. The P-ring winding formed by the third metal layer is connected in series through a through hole to constitute the second inductor. The integrated transformer of claim 1, wherein a center point of the first inductor or the second inductor is connected to a center tap, and the center tap is connected by a third metal layer. form. The integrated transformer of claim 1, wherein the first metal layer is a Re-Distribution Layer (RDL), and the second metal layer is an ultra-thick metal layer (Ultra-Thick Metal) , UTM). The integrated transformer of claim 1, wherein the first inductor and the second electrical The sense uses vertical coupling, oblique coupling, and horizontal coupling to form mutual inductance between each other. The integrated transformer of claim 1, wherein the first inductor further comprises a winding formed by a third metal layer, and the B-ring is spirally wound by the first metal layer. The A-ring winding composed of the second metal layer and the winding system composed of the third metal layer are connected in series to each other to constitute the first inductance. The integrated transformer of claim 1, wherein the first inductor further comprises a winding formed by a third metal layer, and the B-ring is spirally wound by the first metal layer. An A-ring winding composed of the second metal layer and a winding system composed of the third metal layer are connected in series to each other to constitute the first inductor; and the second inductor further includes the third inductor The C-ring formed by the metal layer is spirally wound, and the C-coil winding of the second inductor composed of the second metal layer substantially overlaps with the C-circle spiral winding formed by the third metal layer . The integrated transformer of claim 1, wherein the second inductor further comprises a winding formed by the first metal layer, and the winding of the second inductor is formed by the first metal layer. And disposed outside the spiral winding of the B-ring formed by the first metal layer of the first inductor.