TRANSFORMER COUPLING COEFFICIENT

Abstract

TRANSFORMER COUPLING COEFFICIENT This description relates to a transformer (3) comprising a first coil (300) and a second coil (302) inductively coupled to each other. The first coil comprises at least one first winding (3000) arranged in a first plane to generate a first magnetic field perpendicular to the first plane, and at least one second winding (3002) arranged in the first plane to generate a second magnetic field perpendicular to the first plane and opposite to the first field. In the first plane, a ratio between an area bounded laterally by the first winding (3000) and an area bounded laterally by the second winding (3002) is determined by a target value of a coupling coefficient between the first and second coils (300; 500). Figure for the abstract: Fig. 4

Description

Title of the invention: TRANSFORMER COUPLING COEFFICIENT technical field

[0001] This description relates generally to electronic circuits, for example integrated electronic circuits. This description relates more particularly to a transformer of an integrated circuit. Previous technique

[0002] Transformers are widely used in integrated electronic circuits. A transformer comprises a first coil and a second coil, inductively coupled to each other. One of the first and second coils corresponds to the primary winding of the transformer, and the other corresponds to the secondary winding. The coupling between the primary and secondary windings of the transformer is given by a coupling coefficient K between the two coils.

[0003] A transformer is, for example, used in radio frequency electronic circuits to perform impedance matching between a source of a radio frequency signal and a load that receives the radio frequency signal supplied by the source. Such a transformer is, for example, used as a balancing unit or symmetrical-to-unsymmetrical transformer between the source and the load. By way of example, a radio frequency signal has a frequency greater than or equal to 1 GHz, preferably 5 GHz. For example, a radio frequency signal has a frequency in the range from 1 GHz to 300 GHz. However, such a transformer used as a balancing unit can be used with a signal having a frequency outside the range indicated above by way of example, for example, with a signal that is not a radio frequency signal.

[0004] When a transformer is placed between the source and load impedances, the energy transferred from the source to the load is maximum at a single first resonant frequency if the coupling coefficient K between the primary and secondary windings of the transformer is equal to 1, for example, in absolute value. At the first frequency, the source and load are considered to be matched. In order to ensure the matching of the load and source for more than just the first frequency, it is known to decrease the value of K. By doing so, a second, higher resonant frequency appears. Furthermore, it is known that, by carefully selecting the inductance values ​​of the primary and secondary windings and the value of K, The values ​​of the first and second resonant frequencies can be adapted, or chosen, to achieve a broadband match between the source and the load.

[0005] The ability to construct transformers having a coefficient K of a value equal to a target value is thus particularly interesting, for example, to obtain a broadband matching between a source and a load, although this may be interesting in other applications and circuits including a transformer.

[0006] Known integrated circuit transformers in which the coupling coefficient K between the primary and secondary windings of the transformer can be fixed at a target value suffer, however, from drawbacks, for example, concerning a variation in the area occupied by the transformer when the target value changes, or, for example, concerning a modification of the impedance values ​​of the primary and secondary windings when the target value changes. The area of ​​a transformer is, for example, the total area of ​​a surface in which the transformer is included, for example, in a plane parallel to the windings of the transformer coils. Summary of the invention

[0007] There is a need to overcome all or part of the disadvantages of known transformers, for example, known transformers implemented in integrated circuits, for example, in the metallic layers of an interconnection structure of integrated circuits.

[0008] An embodiment overcomes all or part of the disadvantages of known transformers, for example, known transformers implemented in integrated circuits, for example, in the metallic layers of an interconnection structure of integrated circuits.

[0009] For example, an embodiment provides a transformer in which a modification of the target value of the coupling coefficient K between the primary and secondary windings of the transformer is implemented without changing the surface area occupied by the transformer. In other words, an embodiment provides, for example, a transformer that can have a first implementation corresponding to a first value of K, and a second implementation corresponding to a second value of K, with an identical surface area for both implementations.

[0010] For example, an embodiment provides a transformer in which a modification of the target value of the coupling coefficient K between the primary and secondary windings of the transformer is implemented without changing the inductance values ​​of the first and second windings of the transformer. In other words, an embodiment provides, for example, a transformer that can have a first implementation corresponding to a first value of K, and a second implementation corresponding to a second value of K, a primary inductance value having the same value in these two implementations and a secondary inductance value having the same value in these two implementations.

[0011] One embodiment provides a transformer comprising a first coil and a second coil coupled by induction to each other, in which the first coil comprises: - at least one first winding arranged in a first plane and configured to generate a first magnetic field in a first direction perpendicular to the first plane; and - at least one second winding arranged in the first plane and configured to generate a second magnetic field in a second direction perpendicular to the first plane and opposite to the first direction, in which, in the first plane, a first ratio between a first surface delimited laterally by at least one first winding and a second surface delimited laterally by at least one second winding is determined by a target value of a coupling coefficient between the first and second coils.

[0012] According to one embodiment, the first ratio is different from one.

[0013] According to one embodiment, the at least first winding comprises a plurality of concentric first windings and at least one second winding comprises a plurality of concentric second windings, the number of second windings being, for example, equal to the number of first windings.

[0014] According to one embodiment, the at least one first winding comprises a single first winding and the at least one second winding comprises a single second winding.

[0015] According to one embodiment, the second coil comprises at least a third winding arranged in a second plane and configured to generate a third magnetic field in a third direction parallel to the first and second directions, the second plane being parallel to the first plane.

[0016] According to one embodiment, the second coil is configured to generate only the third magnetic field.

[0017] According to one embodiment: - the second plane is coplanar with the first plane; - a third surface delimited laterally by at least a third winding comprises, in the second plane, a first part included in the first surface and a second part included in the second surface.

[0018] According to one embodiment: - the second shot is different from the first shot; - a third surface delimited laterally by at least one third winding comprises, in the second plane, a first part opposite the first surface and a second part opposite the second surface in a direction parallel to the first and second directions.

[0019] According to one embodiment, the second coil further comprises at least a fourth winding arranged in the second plane and configured to generate a fourth magnetic field in a fourth direction parallel to the first and second directions and opposite to the third direction, the second plane being different from the first plane.

[0020] According to one embodiment, in the second plane, a second ratio between a third surface delimited laterally by at least one third winding and a fourth surface delimited laterally by at least one fourth winding is determined by the target value of the coupling coefficient between the first and second coils.

[0021] According to one embodiment, the at least one third winding comprises a plurality of third windings and the at least one fourth winding comprises a plurality of fourth windings, the number of third windings being equal to the number of fourth windings.

[0022] According to one embodiment, an area occupied by the first coil is the same as an area occupied by the second coil.

[0023] According to one embodiment, the first and second windings are arranged in a first metallic layer and the first and second windings are connected to each other by at least one metallic portion arranged in at least one metallic layer different from the first metallic layer, the length of the at least one metallic portion being determined by a target value of a parasitic capacitance between the first and second windings.

[0024] According to one embodiment, the transformer further comprises a third coil coupled by induction with each of the first and second coils and in which, preferably, the first area ratio is further determined by a target value of a coupling coefficient between the first and third windings.

[0025] An integrated radio frequency circuit comprising a balancing unit connected between a source impedance and a load impedance in a circuit, wherein the balancing unit comprises a transformer as defined above.

[0026] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0027] [Fig.1] represents, by a schematic top view, an example of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0028] Fig. 2 represents, by a schematic top view, another example of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0029] [Fig.3] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0030] [Fig.4] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0031] [Fig.5] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0032] [Fig.6] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0033] [Fig.7] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0034] [Fig.8] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0035] [Fig.9] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value;

[0036] Figure 10 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer having a coupling coefficient between the primary and secondary windings of the transformer equal to a target value; and

[0037] [Fig.1 1] represents, by a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value. Description of the implementation methods

[0038] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0039] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0040] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0041] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0042] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0043] Unless otherwise specified, preferably in the following description, a coil comprises at least one winding or loop that connects the two ends, or terminals, of the coil. In other words, a coil comprises, for example, a single winding or loop that connects the two ends or terminals of the coil, or comprises a plurality of windings or loops connected successively between the two ends or terminals of the coil.

[0044] Unless otherwise specified, preferably in the description that follows, the expression "a winding (or loop) is arranged in a plane" means that: - the winding (or loop) comprises a first part corresponding to more than one-third, preferably more than half, of the length of the winding (or loop), - the first part of the winding (or loop) is contained between a first plane coplanar with a first surface of the first part of the winding (or loop) and a second plane coplanar with a second surface of the first part of the winding (or loop), and - the two planes are also parallel to each other and to the plane in which the winding (or loop) is arranged.

[0045] Fig. 1 represents, by a schematic top view, an example of a transformer 1 having a value of a coupling coefficient between a primary 100 and a secondary 102 of the transformer 1 equal to a target value.

[0046] The primary coil 100 of the transformer 1 comprises a single winding or a single loop 1000. The winding 1000 of the coil 100 is arranged in a first plane or, in other words, in a first layer. For example, the winding 1000 is arranged in a first metal layer of an interconnect structure of an integrated circuit.

[0047] Similarly, the secondary coil 102 of the transformer 1 comprises a single winding or loop 1020. The winding 1020 of the coil 102 is arranged in a second plane or, in other words, in a second layer. The first plane (or layer) and the second plane (or layer) are parallel to each other. For example, the winding 1020 is arranged in a second metal layer of the interconnecting structure.

[0048] The winding 1000 of the primary coil 100 is configured to generate a magnetic field in a direction perpendicular to the foreground. For example, in the foreground, the magnetic field is generated by the coil 100 in a direction perpendicular to the foreground.

[0049] The winding 1020 of the secondary coil 102 is configured to generate a magnetic field in a direction perpendicular to the second plane. For example, in the second plane, the magnetic field is generated by the coil 102 in a direction perpendicular to the second plane.

[0050] Although not shown in [Fig. 1], when the two windings 1000 and 1020 are concentric, the value of the coupling coefficient K between the coils 100 and 102 is at its maximum. The value of K is adjusted, for example decreased, for example in absolute value, relative to the maximum value of K, by sliding winding 1000 relative to winding 1020 in a direction parallel to the first and second planes, without changing the dimensions of either winding 1000 or 1020. One disadvantage of adjusting the value of K by sliding winding 1000 relative to winding 1020 is that the area occupied by the transformer is increased compared to the case where windings 1000 and 1020 are concentric.

[0051] Fig. 2 represents, by a schematic top view, another example of a transformer 2 having a value of the coupling coefficient K between a primary 200 and a secondary 202 of the transformer 2 equal to a target value.

[0052] The primary coil 200 of the transformer 2 comprises a single winding or a single loop 2000. The winding 2000 of the coil 200 is arranged in a first plane or, in other words, in a first layer. For example, the winding 2000 is arranged in a first metal layer of an interconnect structure of an integrated circuit.

[0053] Similarly, the secondary coil 202 of the transformer 2 comprises a single winding or loop 2020. The winding 2020 of the coil 202 is arranged in a second plane or, in other words, in a second layer. The first plane (or layer) and the second plane (or layer) are parallel to each other. The first and second planes may be coplanar or may be different from each other. For example, the winding 2020 is arranged in a second metal layer of the interconnecting structure, which may be identical to the first metal layer or different from the first metal layer.

[0054] The winding 2000 of the primary coil 200 is configured to generate a magnetic field in a direction perpendicular to the foreground. For example, in the foreground, the magnetic field is generated by the coil 200 in a direction perpendicular to the foreground.

[0055] The winding 2020 of the secondary coil 202 is configured to generate a magnetic field in a direction perpendicular to the second plane. For example, in the second plane, the magnetic field is generated by the coil 202 in a direction perpendicular to the second plane.

[0056] The two windings 2000 and 2020 are concentric.

[0057] In transformer 2, the value of K is adjusted by changing the dimensions (e.g., the diameter) of winding 2000, or the dimensions (e.g., the diameter) of winding 2020, or the dimensions (e.g., the diameters) of both winding 2000 and winding 2020, so that the intersection area of ​​the two coils 200 and 202 is changed. However, changing the dimensions of the outermost winding (winding 2020 in the example of [Fig. 2]) will change the surface area of ​​the transformer. Furthermore, changing the dimensions of coil 200, or 202 respectively, will change the impedance value of coil 200, or 202 respectively, and therefore the resonant frequencies of transformer 2.

[0058] In order to overcome at least some of the disadvantages of known transformers, for example known transformers of the types described in relation to Figures 1 and 2, in which the value of the coupling coefficient between the primary and the secondary is equal to a target value, for example less than 1, a transformer is provided here.

[0059] In the intended transformer, one of the primary and secondary windings comprises at least one first winding configured to generate a magnetic field in a first direction and at least one second winding configured to generate a magnetic field in a second direction opposite to the first direction. Furthermore, the first and second windings are coplanar or, in other words, are arranged in the same plane, with the first and second directions perpendicular to this plane. For example, in this plane, the first and second windings together have a general figure-eight shape. For example, when at least one first winding comprises a plurality of first windings, these first windings are concentric with each other and, when at least one second winding comprises a plurality of second windings, these second windings are concentric with each other.

[0060] By changing a ratio between a surface delimited laterally by the first winding(s) and a surface delimited laterally by the second winding(s), the value of the coupling coefficient between the primary and secondary coils is changed, advantageously without changing the surface of the transformer, nor the inductance values ​​of the coils.

[0061] For example, the other of the primary and secondary coils may be arranged in a plane parallel to the plane in which the first and second windings are arranged, these two planes being coplanar or, according to one embodiment, different from each other. When the windings of the two coils are arranged in the same plane, an area occupied by one of these two coils is, for example, included in an area occupied by the other of these two coils. According to one embodiment, when the windings of the two coils are arranged in different parallel planes, the area occupied by one of the two coils is, for example, equal to the area occupied by the other of the two coils, and these two areas are opposite each other in a direction parallel to the first and second directions.

[0062] Various examples of embodiments of such an advantageous transformer will be described in relation to Figures 3 to 11.

[0063] Fig. 3 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 3 having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value.

[0064] The transformer 3 comprises a first coil 300 and a second coil 302 corresponding to the primary and secondary of the transformer 3. For example, coil 300, respectively 302, is the primary, respectively the secondary, of the transformer 3, although, in other examples, coil 300, respectively 302, is the secondary, respectively the primary, of the transformer 3.

[0065] The coil 300 comprises at least one winding or loop 3000 and at least one winding or loop 3002. In the example of [Fig.3], the coil 300 comprises a single winding 3000 and a single winding 3002.

[0066] Windings 3000 and 3002 are arranged in the same foreground. Winding 3000 is configured to generate a magnetic field in a first direction perpendicular to the foreground. For example, in the foreground, the magnetic field generated by winding 3000 is oriented along the first direction. Winding 3002 is configured to generate a magnetic field in a second direction perpendicular to the foreground, and opposite to the first. direction. For example, in the first plane, the magnetic field generated by winding 3002 is oriented along the second direction. Windings 3000 and 3002 taken together, or in other words, coil 300, have a figure-eight shape. In the example in [Fig. 3], coil 300 is, for example, considered to be of the coplanar double-loop type.

[0067] For example, windings 3000 and 3002 are arranged in a first metallic layer. For example, windings 3000 and 3002 are connected to each other by a metallic portion 3004 of a second metallic layer. For example, the second metallic layer is arranged above the first metallic layer in the example of [Fig. 3], although, in other examples, the second metallic layer may be arranged below the first metallic layer. For example, portion 3004 is connected to windings 3000 and 3002 by a conductor via that extends from the first metallic layer to the second metallic layer.For example, a first half of winding 3000 connects a first terminal 3006 of coil 300 to a first end of winding 3002, portion 3004 connects a second end of winding 3002 to a second half of winding 3000, the second half of winding 3000 being connected to a second terminal 3008 of coil 300.

[0068] In the example of [Fig.3], the coil 302 comprises at least one winding or loop 3020. In the example of [Fig.3], the coil 302 comprises a single winding 3020.

[0069] The winding 3020 is arranged in a second plane that is parallel to the first plane. The winding 3020 is configured to generate a magnetic field in a third direction perpendicular to the second plane. For example, in the second plane, the magnetic field generated by the winding 3000 is oriented along the third direction. The third direction is, for example, identical to the first direction or, in other examples, identical to the second direction.

[0070] In the example of [Fig. 3], the coil 302 does not include any additional windings arranged in the second plane and configured to generate a magnetic field in a direction opposite to the third direction. The windings 3020, or in other words, the coil 302, are not figure-eight shaped, but rather, for example, O-shaped. In other words, in the example of [Fig. 3], the coil 302 is not of the coplanar double-loop type. Rather, the coil 302 is, for example, of the single-loop type.

[0071] In the example in [Fig. 3], the first and second planes are different or, in other words, are not coplanar. For example, as shown in [Fig. 3], the first plane is positioned above the second plane, although, in other examples not shown, the foreground is placed below the background.

[0072] For example, the winding 3020 is arranged in a third metallic layer. In the example of [Fig. 3], the coil 300 is positioned above the coil 302, and the third metallic layer is thus positioned below the first metallic layer. In another example not shown, the coil 302 is positioned above the coil 300, and the third metallic layer is positioned above the first metallic layer and corresponds, for example, to the second metallic layer which includes portion 3004. The winding 3020 connects, for example, in the example of [Fig. 3], the two terminals 3022 and 3024 of the coil 302.

[0073] For example, when the first and second planes are different or, in other words, when the coils 300 and 302 are arranged one above the other, in the second plane, a third surface delimited laterally by the winding 3020 comprises a first part opposite, in a direction perpendicular to the first and second planes, the first surface delimited laterally by the winding 3000 and a second part opposite, in a direction perpendicular to the first and second planes, the second surface delimited laterally by the winding 3002.

[0074] Preferably, when the first and second planes are different, an area occupied by the coil 300 is the same as an area occupied by the coil 302. In other words, the footprint of the coil 300 projected onto a plane parallel to the first and second planes is identical to the footprint of the coil 302 projected onto this plane parallel to the first and second planes.

[0075] In the example of [Fig. 3], in the foreground, the ratio between a first surface laterally delimited by winding 3000 and a second surface laterally delimited by winding 3002 is equal to 1. In other words, the first surface is equal to the second surface. Thus, the ratio K between the coils 300 and 302 is minimal and, for example, equal to 0 in an ideal scenario.

[0076] In the example of [Fig. 3], the coil 300 comprises a single winding 3000 and a single winding 3002. In other examples, the coil 300 comprises a plurality of concentric windings 3000 and a plurality of concentric windings 3002, the number of windings 3000 then being equal to the number of windings 3002. More generally, in still other examples, the number of windings 3000 may be different from the number of windings 3002.

[0077] In the example of [Fig.3], the coil 302 comprises a single winding 3020. In other examples, the coil 302 comprises a plurality of concentric windings 3020.

[0078] In the example in [Fig. 3], the coils 300 and 302 are arranged one above the other. In other examples, the coils 300 and 302 are coplanar, or, in other words, the windings 3000, 3002, and 3020 are arranged in the same foreground. In yet other words, in other examples not shown, the foreground and background are coplanar. In such other examples, the coil 302 may be arranged within a surface laterally bounded by the coil 300, or the coil 300 may be arranged within a surface laterally bounded by the coil 302.

[0079] When the first and second planes are coplanar, although this is not shown in [Fig.3], the third surface laterally delimited by the winding 3020 comprises a first part included in the first surface laterally delimited by the winding 3000, and a second part included in the second surface laterally delimited by the winding 3002. In other words, the first part of the third surface corresponds to at least a portion of the first surface, and the second part of the third surface corresponds to at least a portion of the second surface.

[0080] Fig. 4 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 4 having a value of the coupling coefficient between the primary and secondary of the transformer 4 equal to a target value.

[0081] Transformer 4 is similar to transformer 3 and includes many common features with transformer 3. Therefore, only the differences between transformers 3 and 4 are detailed here. For example, unless otherwise specified, everything described for transformer 3 applies to transformer 4.

[0082] Transformer 4 differs from transformer 3 in that the ratio between the first area delimited by winding 3000 of coil 300 and the second area delimited by winding 3002 of coil 300 is not equal to one. Thus, the value of the coupling coefficient K between the primary and secondary windings of transformer 4 differs from the value of the coupling coefficient K between the primary and secondary windings of transformer 3. In transformer 4, the ratio between the first area delimited by winding 3000 of coil 300 and the second area delimited by winding 3002 of coil 300 is determined by a target value of the coupling coefficient K.More specifically, the ratio between the first area delimited by the winding 3000 of the coil 300 and the second area delimited by the winding 3002 of the coil 300 is determined so that the value of the coupling coefficient between the primary and secondary of the transformer 4 is equal to the target value.

[0083] As can be seen in Figures 3 and 4, it is not necessary to modify the surface area of ​​transformer 4 relative to the surface area of ​​transformer 3 to adapt the value of the coupling coefficient K. Furthermore, since the total length of coil 300, respectively 302, is not modified between the two transformers 3 and 4, the value of the inductance of coil 300, respectively 302, is not modified between the two transformers 3 and 4.

[0084] For example, during the design of an integrated circuit including transformer 3 or 4, if at the end of the design phase, before manufacturing, for example during an analog validation phase of the circuit, it appears that the target value of the transformer needs to be modified, for example to adapt the bandwidth and resonant frequencies of the transformer used as a balanced-unbalanced transformer between a load and a source, this could be achieved by a simple modification of the transformer's structure. This simple modification of the structure consists of changing the ratio between the first area delimited by winding 3000 and the second area delimited by winding 3002, without changing the transformer's area and without changing the impedance value of coil 300. Thus, the rest of the circuit advantageously does not need to be modified.

[0085] In the embodiment examples described in relation to Figures 3 and 4, the coil 302 is not of the coplanar double loop type or, in other words, does not have an 8 shape like the coil 300.

[0086] However, the coil 302 may be similar to the coil 300 and be of the double coplanar type as will be described below in relation to figures 5 to 9.

[0087] Fig. 5 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 5 having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value.

[0088] Transformer 5 is similar to transformer 3 and includes many common features with transformer 3. Therefore, only the differences between transformers 3 and 5 are detailed here. For example, unless otherwise specified, everything described for transformer 3 applies to transformer 5.

[0089] Transformer 5 differs from transformer 3 in that coil 302 is replaced by coil 500.

[0090] The coil 500 comprises at least one winding or loop 5000 and at least one winding or loop 5002. In the example of [Fig.5], the coil 500 comprises a single winding 5000 and a single winding 5002.

[0091] Windings 5000 and 5002 are arranged in the same second plane. In the example in [Fig. 5], the first and second planes are not coplanar or, in other words, are different from each other. Winding 5000 is configured to generate a magnetic field in a third direction perpendicular to the first plane. For example, in the second plane, the magnetic field generated by winding 5000 is oriented along the third direction. Winding 5002 is configured to generate a magnetic field in a fourth direction perpendicular to the second plane, and opposite to the third direction. For example, in the second plane, the magnetic field generated by winding 5002 is oriented along the fourth direction. Windings 5000 and 5002 taken together, or, in other words, coil 500, have a figure-eight shape. In the example in [Fig. 5], coil 300 is, for example, said to be of the coplanar double-loop type.

[0092] For example, the windings 5000 and 5002 are arranged in a third metallic layer. For example, the windings 5000 and 5002 are connected to each other by a metallic portion 5004 of a fourth metallic layer.

[0093] For example, in [Fig. 5] where coil 300 is arranged above coil 500, the third metal layer is arranged below the first metal layer of windings 3000 and 3002. For example, in the example of [Fig. 5], the second metal layer of portion 3004 is arranged above the first metal layer. For example, in the example of [Fig. 5], the fourth metal layer of portion 5004 is arranged below the third layer of windings 5000 and 5002.However, in other examples not shown where coil 500 is arranged above coil 300, the fourth metal layer of portion 5004 may be arranged above the third metal layer of windings 5000 and 5002, the third metal layer is arranged above the first metal layer of windings 3000 and 3002, and the first metal layer may be arranged above the second metal layer of portion 3004. For example, portion 5004 is connected to windings 5000 and 5002 by a conductor via extending from the third metal layer to the fourth metal layer.For example, a first half of winding 5000 connects a first terminal 5006 of coil 500 to a first end of winding 5002, portion 5004 connects a second end of winding 5002 to a second half of winding 5000, the second half of winding 5000 being connected to a second terminal 5008 of coil 500.

[0094] Preferably, when the first and second planes are different, the area occupied by the coil 300 is the same as the area occupied by the coil 500. In other words, the footprint of the coil 300 projected onto a plane parallel to the first and second planes is identical to the footprint of the coil 500 projected onto this plane parallel to the first and second planes.

[0095] In the example of [Fig. 5], in the foreground, the ratio between the first surface delimited laterally by the winding 3000 and the second delimited surface The ratio of the surface laterally bounded by the winding 3002 to the surface laterally bounded by the winding 5002 is equal to 1, and, furthermore, in the second plane, the ratio between the third surface laterally bounded by the winding 5000 and the fourth surface laterally bounded by the winding 5002 is equal to 1. In other words, the first surface is equal to the second surface, and the third surface is equal to the fourth surface. In the example in [Fig. 6], the first surface is entirely opposite the fourth surface in a direction perpendicular to the first and second planes, and the second surface is entirely opposite the third surface in a direction perpendicular to the first and second planes.

[0096] Thus, in the example of [Fig. 5], the coupling coefficient has a maximum value, for example in absolute value. Thus, in [Fig. 5], the target value of the coupling coefficient is equal to the maximum value that the coupling coefficient can have in a transformer of the type described in relation to [Fig. 5], where the coils 300 and 500 are each of the coplanar double-loop type and where the coils 300 and 500 are arranged one above the other.

[0097] Fig. 6 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 6 having a value of the coupling coefficient between the primary and secondary of the transformer 6 equal to a target value.

[0098] Transformer 6 is similar to transformer 5 and includes many features in common with transformer 5. Therefore, only the differences between transformers 5 and 6 are detailed here. For example, unless otherwise specified, everything described for transformer 5 applies to transformer 6.

[0099] Transformer 6 differs from transformer 5 in that, in one of the coils 300 and 500, the ratio between the area enclosed by the winding of that coil configured to generate a magnetic field in a direction perpendicular to the plane in which the windings of that coil are arranged, and the area enclosed by the other winding of that coil configured to generate another magnetic field in a different direction perpendicular to the plane of the windings of that coil, is not equal to one. Thus, the value of the coupling coefficient K between the primary and secondary windings of transformer 6 differs from the value of the coupling coefficient K between the primary and secondary windings of transformer 5.

[0100] In the example of [Fig. 6], the ratio between the third area delimited by winding 5000 and the fourth area delimited by winding 5002 is not equal to one, whereas the ratio between the first area delimited by winding 3000 and the second area delimited by winding 3002 is equal to one. In transformer 6, the ratio between the third and fourth areas is determined by a target value of the coupling coefficient K. More specifically, the ratio between the third and fourth surfaces is determined so that the value of the coupling coefficient between the primary and secondary of transformer 6 is equal to the target value.

[0101] As can be seen in Figures 5 and 6, it is not necessary to modify the surface area of ​​transformer 6 relative to the surface area of ​​transformer 5 to adapt the value of the coupling coefficient K. Furthermore, since the total length of coil 300, respectively 500, is not modified between the two transformers 5 and 6, the value of the inductance of coil 300, respectively 500, is not modified between the two transformers 5 and 6.

[0102] Advantageously, the value of the coefficient K can be modified in the transformer 6 compared to the transformer 5 with a simple modification of the structure consisting of modifying the ratio between the third and fourth surfaces, without changing the surface of the transformer, and without changing the impedance values ​​of the respective coils 300 and 500.

[0103] In the example in [Fig.6], the value of the coefficient K is modified by modifying the ratio between the third and fourth surfaces and without changing the ratio between the first and second surfaces. Preferably, the larger of the third and fourth surfaces then comprises a first part opposite, in a direction perpendicular to the first and second planes, the first surface and a second part opposite, in the direction perpendicular to the first and second planes, the second surface.

[0104] In other examples, the value of the coefficient K is modified by changing the ratio between the first and second surfaces and without changing the ratio between the third and fourth surfaces. Preferably, the larger of the first and second surfaces then comprises a first part opposite, in a direction perpendicular to the first and second planes, the third surface and a second part opposite, in the direction perpendicular to the first and second planes, the fourth surface.

[0105] In the two other transformer 6 examples described above, the connection region between windings 3000 and 3002 and the connection region are not arranged one above the other. Thus, although in [Fig. 6] portion 3004 is arranged in a second metallic layer above the first metallic layer of windings 3000 and 3002, in other examples, portion 3004 may be arranged in a second metallic layer below the first metallic layer, and this second metallic layer may then be identical to the second metallic layer of windings 5000 and 5002. Similarly, although in [Fig. 6] portion 5004 is arranged in a fourth metallic layer below the third metallic layer of windings 5000 and 5002, in In other examples, portion 5004 can be arranged in a fourth metallic layer above the first metallic layer, and this fourth metallic layer can then be identical to the first metallic layer of windings 3000 and 3002.

[0106] Fig. 7 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 7 having a value of the coupling coefficient between the primary and secondary of the transformer 7 equal to a target value.

[0107] Transformer 7 is similar to transformer 6 and includes many features in common with transformer 6. Therefore, only the differences between transformers 6 and 7 are detailed here. For example, unless otherwise specified, everything described for transformer 6 applies to transformer 7.

[0108] Transformer 7 differs from transformer 6 in that, in each of the coils 300 and 500, the ratio between the area enclosed by the winding of that coil configured to generate a magnetic field in a direction perpendicular to the plane in which the windings of that coil are arranged, and the area enclosed by the other winding of that coil configured to generate another magnetic field in a different direction perpendicular to the plane in which the windings of that coil are arranged, is not equal to one. Thus, the value of the coupling coefficient K between the primary and secondary windings of transformer 7 differs from the value of the coupling coefficient K between the primary and secondary windings of transformer 5 and from the value of the coupling coefficient between the primary and secondary windings of transformer 6.

[0109] In the example of [Fig. 7], the ratio between the third area delimited by winding 5000 and the fourth area delimited by winding 5002 is not equal to one, and, moreover, the ratio between the first area delimited by winding 3000 and the second area delimited by winding 3002 is not equal to one. In the transformer 7, the ratio between the third and fourth areas and the ratio between the first and second areas are determined by a target value of the coupling coefficient K. More specifically, the ratio between the third and fourth areas and the ratio between the first and second areas are determined such that the value of the coupling coefficient between the primary and secondary windings of the transformer 7 is equal to the target value.

[0110] As can be seen in Figures 5, 6 and 7, it is not necessary to modify the surface area of ​​transformer 6 relative to the surface area of ​​transformers 5 and 6 to adapt the value of the coupling coefficient K. Furthermore, since the total length of the coil 300, respectively 500, is not changed between transformers 5, 6 and 7, the value of the inductance of coil 300, respectively 500, is not changed between transformers 5, 6 and 7.

[0111] Advantageously, the value of the coefficient K can be modified in the transformer 7 compared to the transformer 5 with a simple modification of the structure consisting of modifying the ratio between the third and fourth surfaces and the ratio between the first and second surfaces, without changing the surface of the transformer, and without changing the impedance values ​​of the respective coils 300 and 500.

[0112] Preferably, in the transformer 7 where the coils 300 and 500 are arranged one above the other, the larger of the first surface laterally delimited by the winding 3000 and the second surface laterally delimited by the winding 3002 comprises a first part opposite, in a direction perpendicular to the first and second planes, the third surface delimited by the winding 5000 and a second part opposite, in this direction perpendicular to the first and second planes, the fourth surface delimited by the winding 5002. In other words, in the transformer 7, the connection region between the windings 3000 and 3002 and the connection region are not arranged one above the other.

[0113] Thus, although in [Fig. 7] portion 3004 is arranged in a second metallic layer above the first metallic layer of windings 3000 and 3002, in other examples portion 3004 may be arranged in a second metallic layer below the first metallic layer, and this second metallic layer may then be identical to the second metallic layer of windings 5000 and 5002. Similarly, although in [Fig. 7] portion 5004 is arranged in a fourth metallic layer below the third metallic layer of windings 5000 and 5002, in other examples portion 5004 may be arranged in a fourth metallic layer above the first metallic layer, and this fourth metallic layer may then be identical to the first metallic layer of windings 3000 and 3002.

[0114] In the example of Figures 5, 6 and 7, the coil 300 comprises a single winding 3000 and a single winding 3002. In other examples, the coil 300 comprises a plurality of concentric windings 3000 and a plurality of concentric windings 3002, the number of windings 3000 then being equal to the number of windings 3002. More generally, in still other examples, the number of windings 3000 may be different from the number of windings 3002.

[0115] In the example shown in Figures 5, 6, and 7, the coil 500 comprises a single winding 5000 and a single winding 5002. In other examples not shown, the coil 500 comprises a plurality of concentric windings 5000 and a plurality of concentric windings 5002, the number of windings 5000 then being equal to the number of windings 5002. More generally, in other examples, the number of windings 5000 may be different from the number of windings 5002.

[0116] In the examples in Figures 5, 6, and 7, coils 300 and 500 are arranged one above the other. In other examples not shown, coils 300 and 500 are coplanar, or, in other words, windings 3000, 3002, 5000, and 5002 are arranged in the same first plane. In yet other words, in other examples not shown, the first and second planes are coplanar.Preferably, in these examples, when the ratio of the first and second surfaces is not equal to one, the larger of the first and second surfaces comprises a first part corresponding to a part of the third surface and a second part corresponding to a part of the fourth, and, when the ratio of the third and fourth surfaces is not equal to one, the larger of the third and fourth surfaces comprises a first part corresponding to a part of the first surface and a second part corresponding to a part of the second surface.

[0117] Fig. 8 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 8 having a value of the coupling coefficient between the primary and secondary of the transformer 8 equal to a target value.

[0118] Transformer 8 is similar to transformer 7 and includes many features in common with transformer 7. Therefore, only the differences between transformers 8 and 7 are detailed here. For example, unless otherwise specified, everything described for transformer 7 applies to transformer 8.

[0119] Transformer 8 differs from transformer 7 in that coil 300 comprises a plurality of concentric windings 3000 and a plurality of concentric windings 3002. For example, in [Fig.8], coil 300 comprises two concentric windings 3000 and two concentric windings 3002, although, in other examples, the number of concentric windings 3000 and the number of concentric windings 3002, which are equal to each other, may be greater than two.

[0120] The windings 3000 and 3002 are arranged in the first plane. Furthermore, the concentric windings 3000 are configured to generate a magnetic field in a first direction perpendicular to the first plane. For example, in the first plane, the magnetic field generated by the windings 3000 is oriented along the first direction. The concentric windings 3002 are configured to generate a magnetic field in a second direction perpendicular to the first plane, and opposite to the first direction. For example, in the first plane, the magnetic field generated by the windings 3002 is oriented along the second direction. The windings 3000 and 3002 taken together, or, in other words, the coil 300, have a figure-eight shape and the coil is, for example, said to be of the coplanar double-loop type.

[0121] For example, the windings 3000 and 3002 are arranged in a first metallic layer.

[0122] For example, windings 3000 and 3002 are connected to each other by a metallic part 3004 of at least a second metallic layer.

[0123] For example, in the example of [Fig. 8], a portion 3004 is arranged in a second metallic layer located above the first metallic layer, and another portion 3004 is arranged in yet another second metallic layer located below the first metallic layer. In this example, where the coil 300 is located above the coil 500, the second metallic layer located below the first metallic layer of windings 3000 and 3002 may correspond to the third metallic layer of windings 5000 and 5002 of coil 500. However, the arrangement of the portions 3004 relative to each other and to the first metallic layer may differ from that shown in [Fig. 8].

[0124] In the first plane, the first surface is laterally delimited by the concentric windings 3000, and the second surface is laterally delimited by the concentric windings 3002.

[0125] Transformer 8 also differs from transformer 7 in that coil 500 comprises a plurality of concentric windings 5000 and a plurality of concentric windings 5002. For example, in [Fig. 8], coil 500 comprises two concentric windings 5000 and two concentric windings 5002, although, in other examples, the number of concentric windings 5000 and the number of concentric windings 5002, which are equal, may be greater than two. Furthermore, the number of windings 5000 may be different from the number of windings 3000, although, in the example in [Fig. 8], the number of windings 5000 is equal to the number of windings 3000.

[0126] Windings 5000 and 5002 are arranged in the second plane. Furthermore, the concentric windings 5000 are configured to generate a magnetic field in a third direction perpendicular to the first and second planes. For example, in the second plane, the magnetic field generated by the windings 5000 is oriented along the third direction. The concentric windings 5002 are configured to generate a magnetic field in a fourth direction perpendicular to the first and second planes, and opposite to the third direction. For example, in the second plane, the magnetic field generated by the windings 5002 is oriented along the fourth direction. Windings 5000 and 5002 taken together, or, in other words, the 500 coil, have an 8 shape and the coil is, for example, said to be of the coplanar double loop type.

[0127] For example, windings 5000 and 5002 are arranged in a third metallic layer.

[0128] For example, windings 5000 and 5002 are connected to each other by a metallic portion 5004 of at least a fourth metallic layer.

[0129] For example, in the example of [Fig. 8], a portion 5004 is arranged in a first fourth metallic layer located above the third metallic layer, and another portion 5004 is arranged in a second fourth metallic layer located above the first fourth metallic layer. In this example, where the coil 300 is located above the coil 500, the first fourth metallic layer located above the third metallic layer of windings 5000 and 5002 may correspond to the first metallic layer of windings 3000 and 3002 of coil 500, and the second fourth metallic layer may correspond to the second metallic layer located above the first metallic layer. However, the arrangement of the portions 5004 relative to each other and to the third metallic layer may differ from that illustrated in [Fig. 8].

[0130] In the second plane, the third surface is laterally delimited by the concentric windings 5000, and the fourth surface is laterally delimited by the concentric windings 5002.

[0131] In the example in [Fig. 8], as in that of [Fig. 7], the ratio between the first and second surfaces is not equal to one, and the ratio between the third and fourth surfaces is not equal to one. Furthermore, these two ratios are determined so that the value of the coupling coefficient K is equal to a target value.

[0132] In another example, the ratio between the first and second surfaces is not equal to one, and the ratio between the third and fourth surfaces is equal to one. Furthermore, the ratio between the first and second surfaces is determined so that the value of the coupling coefficient K is equal to a target value.

[0133] In yet another example, the ratio between the first and second surfaces is equal to one, and the ratio between the third and fourth surfaces is not equal to one. Furthermore, the ratio between the third and fourth surfaces is determined so that the value of the coupling coefficient K is equal to a target value.

[0134] In the example in [Fig. 8], the coil 300 comprises a plurality of windings 3000 and a plurality of windings 3002, and the coil 500 comprises a plurality of windings 5000 and a plurality of windings 5002. In other examples, the coil 300 comprises a plurality of windings 3000 and a plurality of windings 3002, and the coil 500 comprises a single winding 5000 and a single winding 5002. In still other examples, coil 300 comprises a single winding 3000 and a single winding 3002 and coil 500 comprises a plurality of windings 5000 and a plurality of windings 5002.

[0135] Furthermore, a person skilled in the art will know how to replace, in transformers 3 and 4 of figures 3 and 4, the coil 300 having a single winding 3000 and a single winding 3002 with a coil 300 having a plurality of windings 3000 and a plurality of windings 3002.

[0136] Fig. 9 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 9 having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value.

[0137] Transformer 9 is similar to transformer 8 and includes many features in common with transformer 8. Therefore, only the differences between transformers 9 and 8 are detailed here. For example, unless otherwise specified, everything described for transformer 8 applies to transformer 9.

[0138] The transformer 9 differs from the transformer 8 in that the portions 3004 connecting the windings 3000 and 3002 together are longer in the transformer 9 than in the transformer 8. Changing the length of the portions 3004 makes it possible to change the value of the parasitic capacitance between the windings 3000 and 3002. Thus, according to one embodiment, when the windings 3000 and 3002 are connected together by at least one metallic portion 3004 arranged in at least a second metallic layer different from the first metallic layer of the windings 3000 and 3002, and the length of the portions 3004 is determined by a target value of the parasitic capacitance between the windings 3000 and 3002.

[0139] In the example in [Fig.9], the portions 3004 are all arranged in the same second metallic layer, although, in other examples, two different portions 3004 may be arranged in two different second metallic layers, as has been shown for example in [Fig.8].

[0140] The transformer 9 differs from the transformer 8 in that the portions 5004 connecting the windings 5000 and 5002 together are longer in the transformer 9 than in the transformer 8. Changing the length of the portions 5004 makes it possible to change the value of the parasitic capacitance between the windings 5000 and 5002. Thus, according to an embodiment, in which the windings 5000 and 5002 are connected together by at least one metallic portion 5004 arranged in at least a fourth metallic layer different from the third metallic layer of the windings 5000 and 5002, and the length of the portions 5004 is determined by a target value of the parasitic capacitance between the windings 5000 and 5002.

[0141] In the example of [Fig.9], the portions 5004 are all arranged in the same fourth metallic layer, which can correspond to the first metallic layer of the windings 3000 and 3002 as shown in [Fig.9], although, in other examples, two different portions 5004 can be arranged in two different fourth metallic layers, as shown for example in [Fig.8].

[0142] Fig. 10 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer 10 having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value.

[0143] Transformer 10 is similar to transformer 9 and includes many features in common with transformer 9. Therefore, only the differences between transformers 10 and 9 are detailed here. For example, unless otherwise specified, everything described for transformer 9 applies to transformer 10.

[0144] Transformer 10 differs from transformer 9 in that coil 500 is replaced by coil 1000, and the winding(s) of coil 1000 are arranged in a second plane that is coplanar with the first plane. Thus, the winding(s) of coil 1000 are coplanar with windings 3000 and 3002 of coil 300.

[0145] For example, in [Fig. 10], the coil is of the single-loop type and comprises a plurality of concentric windings 10000, for example two windings 1000, configured to generate a magnetic field in a direction perpendicular to the first and second planes. For example, the windings 10000 are arranged in a second metallic layer that is the same as the first metallic layer of the windings 3000 and 3002. For example, between two ends 10006 and 10008 of the coil 1000, the windings 10000 are connected to each other by at least one metallic portion 10004 arranged in at least a fourth metallic layer different from the third metallic layer of the windings 10000.

[0146] In [Fig.10], the ratio between the first surface laterally delimited by the windings 3000 and the second surface laterally delimited by the windings 3002 is determined so that the value of the coupling coefficient is equal to a target value.

[0147] Preferably, when a transformer, for example transformer 10, comprises a coil 300 of the coplanar double loop type and a coil 1000 of the single loop type, and the windings of the coils 300 and 1000 are arranged in the same plane, in this plane, the third surface delimited laterally by the windings 1000 comprises a first part corresponding to a part of the first surface, and a second part corresponding to a part of the second surface.

[0148] A person skilled in the art will be able to adapt the example in [Fig. 10] to other examples where the number of windings 3000 of coil 300 is not two, for example equal to one or greater than two. Similarly, a person skilled in the art will be able to adapt the example in [Fig. 10] to other examples where the number of windings 10000 of coil 100 is not two, for example equal to one or greater than two.

[0149] In the example in [Fig. 10], the coil 1000 is located within an interior surface of the coil 300. Thus, the surface area occupied by the coil 1000, projected onto a plane parallel to the first and second planes, is entirely contained within the surface area occupied by the coil 300, projected onto this plane parallel to the first and second planes. However, a person skilled in the art will be able to adapt the example in [Fig. 10] to other examples where the coil 300 is located within an interior surface of the coil 1000. In these other examples, the surface area occupied by the coil 300, projected onto a plane parallel to the first and second planes, is entirely contained within the surface area occupied by the coil 1000, projected onto this plane parallel to the first and second planes.

[0150] In all the embodiments described above in relation to Figures 3 to 10, each transformer comprises only two coils corresponding to the primary and a first secondary winding of the transformer. However, all these embodiments can be generalized to the case where the transformer includes an additional coil corresponding to a second secondary winding. More generally, all the examples described above can be generalized to the case where the transformer comprises more than three coils coupled together.

[0151] For example, when a third coil is added to a transformer of the type described in relation to Figures 3 to 10, a value of the coupling coefficient between the first coil 300 and the second coil is determined, at least in part, by the ratio between the first area delimited by the winding(s) 3000 and the second area delimited by the winding(s) 3002, such that the value of this first coupling coefficient is equal to a first target value. Furthermore, a value of the coupling coefficient between the first coil 300 and the third coil is, for example, determined, at least in part, by the ratio between the first and second areas, such that the value of this second coupling coefficient is equal to a second target value.As an example, when the second coil is of the coplanar double loop type, the value of the coupling coefficient between the second and third coils is determined, at least in part, by the ratio between the third and fourth surfaces of the second coil, so that the value of this third coupling coefficient is equal to a third target value.

[0152] Preferably, the winding(s) of the third coil are arranged in a third plane parallel to the first and second planes. Preferably, the third plane is different from the first and second planes.

[0153] An example of a three-coil transformer is described in relation to [Fig. 11].

[0154] Figure 11 represents, by way of a schematic three-dimensional view, an example of an embodiment of a transformer having a value of the coupling coefficient between the primary and secondary of the transformer equal to a target value.

[0155] In the example of [Fig. 11], a third coil 1100 corresponding to the second secondary of the transformer is added to the transformer 7 of [Fig.7], in order to obtain a transformer 11 comprising a primary coil and two secondary coils.

[0156] Thus, transformer 11 is similar to transformer 7 and shares many features with transformer 7. Therefore, only the differences between transformers 11 and 7 are detailed here. For example, unless otherwise specified, everything described for transformer 7 applies to transformer 11.

[0157] Transformer 11 differs from transformer 7 in that it includes the third coil 1100. The winding(s) of coil 1100 are arranged in a third plane parallel to the first plane of the windings of the first coil 300 and the windings of the second coil 500.

[0158] Preferably, the third plane is different from the first and second planes, and the coil 1100 is arranged above the coils 300 and 500. In such a case, the surface of the coil 300, the surface of the coil 500 and the surface of the coil 1100, when projected onto the same plane parallel to the first, second and third planes, are identical.

[0159] For example, the coil 1100 comprises at least one winding 11000 configured to generate a magnetic field in a fifth direction perpendicular to the third plane, at least one winding 11002 configured to generate a magnetic field in a sixth direction parallel and opposite to the fifth direction, and at least one winding 11004 configured to generate a magnetic field in a seventh direction parallel and opposite to the sixth direction. The coil 11000 is then, for example, of the coplanar triple-loop type.

[0160] In the example of [Fig.1 1], the coil 1100 comprises a single winding 11000, a single winding 11002 and a single winding 11004. In another example, the coil 1100 may comprise a plurality of windings 11000 concentric with each other, a plurality of windings 11002 concentric with each other, and a plurality of windings 11004 concentric with each other.

[0161] According to one embodiment, a transformer of the type described in relation to Figures 3 to 11 is provided in a balancing unit configured to be connected between a source impedance and a load impedance.

[0162] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to them. In particular, as previously mentioned, those skilled in the art will be able to adapt the embodiments and examples described above for a transformer having two or three coils coupled together to cases of coils having a number N greater than 3. For example, a transformer having an even number N of coils greater than 3 could be considered as an assembly, for example a stack, of a plurality of transformers having only two coils.For example, a transformer with an even number N of coils greater than 3 can be considered as an assembly, for example a stack, of a plurality of transformers of the type described in relation to Figures 2 to 10. For example, a transformer with an odd number N of coils greater than 3 can be considered as an assembly, for example a stack, of one or a plurality of transformers with only two coils and exactly one transformer with three coils. For example, a transformer with an odd number N of coils greater than 3 can be considered as an assembly, for example a stack, of one or a plurality of transformers of the type described in relation to Figures 2 to 10 and exactly one transformer of the type described in relation to [Fig. 11].

[0163] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional specifications given above. In particular, a person skilled in the art will be able to modify the ratio between the first and second surfaces and, for example, the ratio between the third and fourth surfaces, in order to obtain a coupling coefficient value equal to a target value. For example, in order to find the value of the ratio between the first and second surfaces, and, for example, the ratio between the third and fifth surfaces corresponding to a given target value, a person skilled in the art will be able to simulate different ratio values ​​using an electromagnetic simulation tool, for example, a simulation tool based on finite element simulation or, for example, the simulation tool marketed under the trade name Keysight RFPro.The person skilled in the art will also know how to use these simulation tools to try different lengths of metal portion to connect the windings of a coplanar double loop coil together in order to obtain the length. which corresponds to a given capacitance value for the parasitic capacitance between the windings of this coil, for example to minimize this capacitance value.

Claims

Demands

1. Transformer (3;4;5;6;7;8;9;10;11) comprising a first coil (300) and a second coil (302; 500; 1000) coupled by induction to each other, in which the first coil comprises: - at least one first winding (3000) arranged in a first plane and configured to generate a first magnetic field in a first direction perpendicular to the first plane; and - at least one second winding (3002) arranged in the first plane and configured to generate a second magnetic field in a second direction perpendicular to the first plane and opposite to the first direction, in which, in the first plane, a first ratio between a first surface delimited laterally by the at least one first winding (3000) and a second surface delimited laterally by the at least one second winding (3002) is determined by a target value of a coupling coefficient between the first and second coils (300; 302, 500).

2. Transformer (4; 6; 7; 8; 9; 10; 11) according to claim 1, wherein the first ratio is different from one.

3. Transformer (8; 9; 10) according to claim 1 or 2, wherein at least one first winding (3000) comprises a plurality of concentric first windings (3000) and at least one second winding (3002) comprises a plurality of concentric second windings (3002), the number of second windings (3002) being, for example, equal to the number of first windings (3000).

4. Transformer (3;4;5;6;7;11) according to claim 1 or 2, wherein at least one first winding (3000) comprises a single first winding and at least one second winding (3002) comprises a single second winding.

5. Transformer (3; 4; 5; 6; 7; 8; 9; 10; 11) according to any one of claims 1 to 4, wherein the second coil (302; 500; 1000) comprises at least one third winding (3020; 5000; 10000) arranged in a second plane and configured to generate a third magnetic field in a third direction parallel to the first and second directions, the second plane being parallel to the first plane.

6. Transformer (3; 4; 10) according to claim 5, wherein the second coil (302; 1000) is configured to generate only the third magnetic field.

7. Transformer (10) according to claim 6, wherein: - the second plane is coplanar with the first plane; - a third surface laterally delimited by T at least a third winding (10000) comprises, in the second plane, a first part included in the first surface and a second part included in the second surface.

8. Transformer (3;4;5;6;7;8;9;11) according to claim 6, wherein: - the second plane is different from the first plane; - a third surface laterally delimited by T at least a third winding (3020; 5000) comprises, in the second plane, a first part opposite the first surface and a second part opposite the second surface in a direction parallel to the first and second directions.

9. Transformer (5; 6; 7; 8; 9; 11) according to claim 5, wherein the second coil (500) further comprises at least a fourth winding (5002) arranged in the second plane and configured to generate a fourth magnetic field in a fourth direction parallel to the first and second directions and opposite to the third direction, the second plane being different from the first plane.

10. Transformer (5;6;7;8;9;11) according to claim 9, wherein, in the second plane, a second ratio between a third surface laterally delimited by T at least a third winding (5000) and a fourth surface laterally delimited by T at least a fourth winding (5002) is determined by the target value of the coupling coefficient between the first and second coils (300; 500).

11. Transformer (8; 9) according to claim 9 or 10, wherein at least one third winding (5000) comprises a plurality of third windings (5000) and at least one fourth winding (5002) comprises a plurality of fourth windings windings (5002), the number of third windings (5000) being equal to the number of fourth windings (5002).

12. Transformer (3;4;5;6;7;8;9;11) according to any one of claims 8 to 11, wherein an area occupied by the first coil is the same as an area occupied by the second coil.

13. Transformer (9) according to any one of claims 1 to 12, wherein the first and second windings (3000; 3002) are arranged in a first metallic layer and the first and second windings are connected to each other by at least one metallic portion (3004) arranged in at least one metallic layer different from the first metallic layer, the length of at least one metallic portion (3004) being determined by a target value of a parasitic capacitance between the first and second windings (3000; 3002).

14. Transformer (11) according to any one of claims 1 to 13, wherein the transformer further comprises a third coil (1100) inductively coupled with each of the first and second coils (300; 500) and wherein, preferably, the first area ratio is further determined by a target value of a coupling coefficient between the first and third windings.

15. Integrated radio frequency circuit comprising a balancing unit connected between a source impedance and a load impedance in a circuit, wherein the balancing unit comprises a transformer (3; 4; 5; 6; 7; 8; 9; 10; 11) according to any one of claims 1 to 14.