1. Field of the Invention
The present invention relates to an integrated inductor structure and an integrated transformer structure, especially to a highly symmetric 8-shaped integrated inductor and integrated transformer.
2. Description of Related Art
Inductors and transformers are important elements in radio frequency integrated circuits to implement single-ended to differential signal conversion, signal coupling and impedance matching. As System-on-chips (SoC) become the mainstream of integrated circuits, integrated inductors and integrated transformers gradually substitute conventional discrete elements and are commonly applied to radio frequency integrated circuits. However, inductors and transformers in integrated circuits often take up large areas; therefore, it becomes an important issue to reduce the areas of inductors and transformers in integrated circuits without degrading element performances, such as inductance, quality factor (Q), and coupling coefficient (K).
In view of the issues of the prior art, an object of the present invention is to provide an integrated inductor structure and an integrated transformer structure to improve the symmetry and the inductance of inductors.
The present invention discloses an integrated inductor structure comprising a first spiral coil, a second spiral coil and a connecting metal segment. The first spiral coil comprises a plurality of metal segments and a bridging metal segment and has a first terminal, a second terminal, a third terminal and a fourth terminal. The bridging metal segment is for connecting the metal segments, and the bridging metal segment and the metal segments are implemented in different layers. The second spiral coil has a fifth terminal and a sixth terminal. The connecting metal segment connects the third terminal with the fifth terminal and connects the fourth terminal with the sixth terminal. The integrated inductor structure utilizes one of the first terminal and the second terminal as an input terminal and the other as an output terminal, the first terminal and the third terminal are on a first imaginary straight line, the first imaginary straight line passes a central region of a region surrounded by the first spiral coil, the bridging metal segment and the central region of the region are on a second imaginary straight line, and an included angle between the first imaginary straight line and the second imaginary straight line is equal to or greater than 45 degrees and equal to or smaller than 90 degrees.
The present invention also discloses an integrated transformer structure comprising a first spiral coil, a second spiral coil and a connecting metal segment. The first spiral coil comprises a plurality of metal segments and a bridging metal segment, and has a first terminal, a second terminal, a third terminal and a fourth terminal. The bridging metal segment is for connecting the metal segments and the bridging metal segment and the metal segments are implemented in different layers. The second spiral coil has a fifth terminal, a sixth terminal, a seventh terminal and an eighth terminal. The connecting metal segment, connects the third terminal with the fifth terminal and connects the fourth terminal with the sixth terminal. The integrated inductor structure utilizes the first terminal and the second terminal as an input port and the seventh terminal and the eighth terminal as an output port, the first terminal and the third terminal are on a first imaginary straight line, the first imaginary straight line passes a central region of a region surrounded by the first spiral coil, the bridging metal segment and the central region of the region are on a second imaginary straight line, and an included angle between the first imaginary straight line and the second imaginary straight line is equal to or greater than 45 degrees and equal to or smaller than 90 degrees.
The integrated inductor structures and the integrated transformer structures of this invention have high symmetry, which is beneficial to improving the inductance. In addition, because the distance between the input terminals of the inductor is not subject to the number of turns of the spiral coil, it is easy to connect the inductor with differential elements in the integrated circuit.
These and other objectives of the present invention no doubt becomes obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiments with reference to the various figures and drawings.
The following description is written by referring to terms of this technical field. If any term is defined in this specification, such term should be explained accordingly. In addition, the connection between objects or events in the below-described embodiments can be direct or indirect provided that these embodiments are practicable under such connection. Said “indirect” means that an intermediate object or a physical space exists between the objects, or an intermediate event or a time interval exists between the events.
The terminals 211 and 212 are located at an outer coil of the spiral coil 210 while the terminals 213 and 214 are located at an innermost coil of the spiral coil 210. On the other hand, the terminals 223 and 224 are located at the innermost coil of the spiral coil 220. The spiral coil 210 and the spiral coil 220 are connected through a connecting metal segment, which comprises the bridging metal segments 230 and 240. The bridging metal segment 230 connects the terminal 213 and the terminal 224; the bridging metal segment 240 connects the terminal 214 and the terminal 223. In this embodiment, the metal segments of the spiral coil 210 and the spiral coil 220, except the bridging metal segments, are implemented in the first metal layer; the bridging metal segments 230 and 240, which are respectively implemented in the second metal layer and the third metal layer, form a crossing structure. Therefore, the bridging metal segments 230 and 240 can overpass multiple metal segments (located in the first metal layer) that constitute the spiral coil 210 and the spiral coil 220, such that the innermost coils of the spiral coil 210 and the spiral coil 220 are connected through the connecting metal segment. In another embodiment, the connecting metal segment may not be a crossing structure, i.e., one of the bridging metal segments connects the terminal 213 and the terminal 223 while the other bridging metal segment connects the terminal 214 and the terminal 224. In this case the connecting metal segment can be implemented in a single metal layer.
In fact, both the spiral coil 210 and the spiral coil 220 are symmetric spiral coils and are in a back-to-back arrangement. After the terminals located at the inner coils of the spiral coil 210 and the spiral coil 220 (i.e., the terminals 213, 214, 223 and 224) are connected via the connecting metal segment, an 8-shaped integrated inductor structure is formed. A central tap 221 of the 8-shaped integrated inductor 200 can be formed at the spiral coil 220 at a position corresponding to the terminals 211 and 212 of the spiral coil 210. As a result, a port of the 8-shaped integrated inductor 200 (the port is formed by the terminal 211 and the terminal 212), the connecting metal segment and the central tap 221 are on one straight line 250, and the 8-shaped integrated inductor 200 is symmetric with respective to the straight line 250. Therefore, the 8-shaped integrated inductor 200 of this invention has better symmetry as opposed to the conventional 8-shaped integrated inductor 100, and the distance between the terminal 211 and the terminal 212 is reduced and is not subject to the number of turns of the spiral coil, hence making the 8-shaped integrated inductor 200 more suitable for differential circuits. When the 8-shaped integrated inductor 200 is applied to a differential circuit, the central tap 221 can be connected to the ground or a voltage source VDD of the differential circuit.
The region surrounded by the spiral coil 210 includes a central region 217 (similarly, the spiral coil 220 includes a central region 227). The central region 217 is approximately located in the center of the innermost coil of the spiral coil 210; that is, the distances h1 and h2 between the central region 217 and its upper and lower metal segments are approximately equal, and the distances d1 and d2 between the central region 217 and its left and right metal segments are approximately the same. In this embodiment, the bridging metal segments 216a and 216b are located on the sides of the spiral coil 210 parallel to the straight line 250. In other words, the straight line 250 does not pass the bridging metal segments 216a and 216b. However, when the spiral coil 210 is not implemented as a rectangle (for example, implemented as other polygons or even as a circle), the position of the bridging metal segment 216a (or 216b) can be further defined as the following. For the spiral coil 210, a first imaginary straight line can be formed by connecting the first terminal or the second terminal with the third terminal or the fourth terminal (i.e., approximately the straight line 250), and a second imaginary straight line can be formed by connecting the bridging metal segment 216a (or 216b) with the central region 217 of the region surrounded by the spiral coil 210 (i.e., approximately the straight line 260). An included angle (taking the smaller one as the subject for discussion) formed by the two imaginary straight lines can be equal to or greater than 45 degrees and equal to or smaller than 90 degrees (in the embodiment of
Similar to the embodiment shown in
To better illustrate the connections among the terminals of the spiral coil 310 and spiral coil 320 and the connecting metal segment 380 in more detail,
For the 8-shaped integrated inductors in
In addition to the aforementioned 8-shaped integrated inductors, this invention also discloses an integrated transformer structure. The integrated transformer structure is formed by modifying the central tap of the 8-shaped integrated inductor in each of the
In addition to the method described above, the integrated transformer of this invention can be implemented by duplicating any of the 8-shaped integrated inductors in
Note that although the bridging metal segments in
The shape, size, and ratio of any element in the disclosed figures are exemplary for understanding, not for limiting the scope of this invention. The aforementioned descriptions represent merely the preferred embodiments of the present invention, without any intention to limit the scope of the present invention thereto. Various equivalent changes, alterations, or modifications based on the claims of the present invention are all consequently viewed as being embraced by the scope of the present invention.
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104132810 A | Oct 2015 | TW | national |
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Entry |
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State Intellectual Property Office of the People's Republic of China , “Office Action”, dated Nov. 16, 2017. |
Taiwan Intellectual Property Office, TIPO, Office Action dated Feb. 2, 2018 in counterpart Taiwan application 105124973. Summary: The OA letter recites that TW201248658 and JP2005327931A render claims 1-3 obvious. |
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Number | Date | Country | |
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20170098500 A1 | Apr 2017 | US |