Structure of a transformer

Abstract

Structure of a transformer The present description relates to a transformer (300) comprising two inductors (110, 140), the first inductor comprising a loop (116) comprising conductive tracks (305) in first and second levels of the structure, the conductive tracks being adapted to be electrically connected to each other directly, or by an intermediate conductive track, over at least half the length of the loop; wherein, over at least half the length of the loop, the conductive tracks are arranged so that, in a sectional view perpendicular to the length of the first loop, the center of mass (D1) of the first conductive track is laterally offset from the center of mass (D2) of the second conductive track in the sectional plane, and in a direction parallel to the plane formed by the first level. Figure for abstract: Fig. 3

Description

Title of the invention: Structure of a transformer Technical field

[0001] This description relates generally to transformers and methods of manufacturing transformers. Prior art

[0002] A transformer generally comprises two magnetically coupled inductors and transfers power from one inductor to the other. Transformers can be used for various applications, such as for power matching or converting differential signals into common mode and vice versa, as the name suggests, with a balun (from the English "balanced-unbalanced"). In particular, an impedance transformer is an electronic component designed to modify the impedance between two terminals of an electronic circuit. There is a need for transformers that are more efficient and / or operational over a wider frequency range and / or with better capacitive coupling between the inductances. Summary of the invention

[0003] One embodiment provides a transformer comprising, in a laminated structure, a first inductor and a second inductor, the first inductor comprising: - a first loop comprising a first conductive track in a first level of the structure and a second conductive track in a second level of the structure, the first and second conductive tracks being adapted to be electrically connected to each other directly, or by an intermediate conductive track, over at least half the length of the first loop; wherein, over at least half the length of the first loop, the first and second conductive tracks are arranged such that, in a sectional view perpendicular to the length of the first loop, the center of mass of the first conductive track is laterally offset from the center of mass of the second conductive track in the sectional plane, and in a direction parallel to the plane formed by the first level.

[0004] According to one embodiment, the first and second conductive tracks are connected to each other by the intermediate conductive track, the intermediate conductive track comprising one or more vias.

[0005] According to one embodiment, the first loop further comprises a third conductive track electrically connected to the second conductive track on at least one side. less than half the length of the first loop, wherein the second conductive track comprises one or more vias connecting the first conductive track to the third conductive track.

[0006] According to one embodiment, the second inductor comprises a first loop comprising a fourth conductive track in the first level of the structure and a fifth conductive track in the second level of the structure.

[0007] According to one embodiment, the first conductive track of the first loop of the first inductance in the first level is at least partially opposite the fifth track of the first loop of the second inductance in the second level.

[0008] Another embodiment provides a method of manufacturing a transformer comprising, in a laminated structure, a first inductor and a second inductor, the method comprising: - the formation, in a first level of the structure, of a first conductive track of a first loop of a first inductance; - the formation, in a second level of the structure, of a second conductive track of the first loop, the first and second conductive tracks being adapted to be electrically connected to each other directly, or by an intermediate conductive track, over at least half the length of the first loop; wherein, over at least half the length of the first loop, the first and second conductive tracks are arranged such that, in a sectional view perpendicular to the length of the first loop, the center of mass of the first conductive track is laterally offset from the center of mass of the second conductive track in the sectional plane, and in a direction parallel to the plane formed by the first level.

[0009] According to one embodiment, the first and second conductive tracks are connected to each other by the intermediate conductive track, the method further comprising, after the formation of the first conductive track and before the formation of the second conductive track, the formation of at least one via forming the intermediate conductive track on the first conductive track, the second conductive track being formed on the at least one via so that the first and second conductive tracks are electrically connected to each other by means of the at least one via.

[0010] According to one embodiment, the second conductive track comprises one or more vias, the method further comprising, after the formation of the second conductive track, the formation of a third conductive track on the second conductive track, the third conductive track being electrically connected to the second conductive track over at least half the length of the first loop.

[0011] According to one embodiment: - the formation, in the first level of the structure, of a fourth conductive track of a first loop of the second inductance; - the formation, in the second level of the structure, of a fifth conductive track of the first loop of the second inductance.

[0012] According to one embodiment, the fifth track of the first loop in the second level is formed so that the first conductive track of the first loop in the first level is at least partially opposite the fifth track of the first loop in the second level. Brief description of the drawings

[0013] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0014] [Fig.l] is a top view of a transformer comprising two inductors;

[0015] [Fig.2] is a partial sectional view of the transformer of [Fig.l];

[0016] [Fig.3] is a top view of a transformer according to an embodiment of this description;

[0017] [Fig.4] is a partial sectional view of the transformer of [Fig.3] according to an embodiment of the present description;

[0018] [Fig.5A] is a graph representing the value of the first inductance of the transformer of figures 1 and 3 as a function of the frequency of use of the transformer;

[0019] [Fig.5B] is a graph representing the value of the second inductance of the transformer of figures 1 and 3 as a function of the frequency of use of the transformer;

[0020] [Fig.5C] is a graph representing the value of the mutual coupling parameter between the two inductances of the transformer of figures 1 and 3 as a function of the frequency of use of the transformer;

[0021] [Fig.5D] is a graph representing the series resistance of the first inductance of the transformer of Figures 1 and 3 as a function of the frequency of use of the transformer;

[0022] [Fig.5E] is a graph representing the series resistance of the second inductance of the transformer of Figures 1 and 3 as a function of the frequency of use of the transformer;

[0023] [Fig.6A] is a graph representing S parameters (in English, “scattering pa- rameters”) of adaptation at the input, output and transmission of the signal by the transformers of figures 1 and 3 at a frequency of 25GHz;

[0024] [Fig.6B] is a graph representing parameters S of adaptation at input, output and transmission of the signal by the transformers of figures 1 and 3 at a frequency of 20GHz;

[0025] [Fig.6C] is a graph representing S parameters of adaptation at input, output and transmission of the signal by the transformers of figures 1 and 3 at a frequency of 42GHz;

[0026] [Fig.7A] is a top view of an exemplary transformer according to an embodiment of the present description;

[0027] [Fig.7B] and [Fig.7C] are top views of a first and a second inductance of the transformer of [Fig.7A];

[0028] [Fig.8A] is a graph representing parameters S of adaptation at input, output and transmission of the signal by the transformers of figures 1 and 3 at a frequency of 12GHz;

[0029] [Fig.8B] is a graph representing S parameters of adaptation at input, output and transmission of the signal by the transformers of figures 1 and 3 at a frequency of 9GHz;

[0030] [Fig.8C] is a graph representing parameters S of adaptation at input, output and transmission of the signal by the transformers of figures 1 and 3 at a frequency of 13 GHz; and

[0031] [Fig.9] is a partial sectional view of the transformer of [Fig.1] according to an example other than that of [Fig.2] and according to an embodiment of the present description. Description of the embodiments

[0032] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0033] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed.

[0034] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0035] In the following description, when referring to position qualifiers absolute, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative, such as the terms "above", "below", "upper", "lower", etc., or orientation qualifiers, such as the terms "horizontal", "vertical", etc., are referred to unless otherwise specified to the orientation of the figures.

[0036] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0037] In the remainder of the description, transformers formed in a laminated structure are considered. By “laminated structure” is meant a stack of insulating and conductive levels coating a substrate. Here, the term “conductive level” refers to a set of conductive tracks defined in the same layer of a conductive material, for example a metal, for example copper.

[0038] [Fig.l] is a top view of an example of a transformer 100 comprising two inductors 110, 140. For example, the transformer 100 is used as a balun and power adapter: a common mode signal is for example transformed into a differential mode signal, the input impedance is for example adapted to 50 Ohms, the output impedance is for example adapted to 100 Ohms.

[0039] According to one embodiment, the first inductor 110 is connected to a first external electronic circuit (not shown in [Fig.l]) and the second inductor 140 is connected to a second external electronic circuit (also not shown in [Fig.l]).

[0040] The inductor 110 comprises two connection terminals, for example an input / output terminal 112 and an input / output terminal 114. The inductor 110, as shown in the example of [Fig.l], comprises a loop 116, i.e. one or more conductive tracks connected to each other and comprising a complete turn, connecting a first end 118 to a second end 120. The first end 118 is for example connected to the connection terminal 112 and the second end 120 is for example connected to the connection terminal 114.

[0041] The inductor 140 comprises two connection terminals, for example an input / output terminal 142 and an input / output terminal 144. The inductor 140, as shown in the example of [Fig.l], comprises two loops: a first loop formed of the two half-loops 146 and 148, and a second loop 147. The first half-loop 146 of the first loop connects one end 150 to one end 152. The end 150 is for example connected to the connection terminal 142. The second loop 147 connects one end 154 to one end 156. The end 154 is for example connected to the end 152 by one or more conductive tracks. The second half-loop 148 of the first loop connects an end 158 to an end 160. The end 158 is for example connected to the end 156 by means of one or more conductive tracks and / or one or more vias. The end 160 is for example example connected to connection terminal 144.

[0042] In the example of [Fig. 1], the loops 116 and 147, and the loop formed by the set of half-loops 146 and 148, are of substantially rectangular shape. In other embodiments, the loops are for example of shapes other than rectangular, such as octagonal, circular, etc.

[0043] The loop 116 of the first inductance 110, the two half-loops 146, 148 of the second inductance 140 and the second loop 147 of the second inductance 140 are formed from a stack of three conductive tracks, each being in a distinct level, as will be described in relation to [Fig.2].

[0044] [Fig.2] schematically represents a partial sectional view of the transformer 100 of [Fig.l] along an axis A1 represented in [Fig.l] crossing the loop 116, the half-loop 146 and the loop 147.

[0045] The loops of the inductances 110 and 140 of the transformer 100 of [Fig. 1] each comprise, for example, conductive tracks in levels L1, L2, L3 so that the level L2 is intermediate to the levels L1 and L3. The levels L1 and L3 are, for example, metallization levels and the level L2 is, for example, an insulating level in which vias can be formed in order to connect conductive tracks of the metallization levels. Conductive tracks formed in the level L2 are, for example, vias.

[0046] Loop 116 comprises a conductive track 205 in level L1, a conductive track 210 in level L2 and a conductive track 215 in level L3.

[0047] The half-loop 146 comprises a conductive track 225 in the level L1, a conductive track 230 in the level L2 and a conductive track 235 in the level L3.

[0048] A distance dl separates the loop 116 and the half-loop 146 at the axis A1 and a distance d2 separates the half-loop 146 and the loop 147 at the axis A1, these distances dl and d2 also being shown in [Fig.l]. In the example of Figures 1 and 2, the distance d2 is greater than the distance dl.

[0049] In the sectional view of [Fig. 2], the conductive tracks 205, 210 and 215 of each loop are centered on the same axis S, that is to say that their sections have their centers of mass, C1, C2 and C3 respectively, aligned along the axis S. The axis S is in the sectional plane of [Fig. 2] and perpendicularly intersects the levels L1, L2 and L3. For the definition of the center of mass, it is considered that each of the conductive tracks 205, 210 and 215 has a uniform density.

[0050] Referring again to [Fig.l], loop 116, each of the half-loops 146, 148 and loop 147 comprise conductive tracks in levels L1, L2 and L3 connected together over the entire length of the loop. The conductive tracks connecting ends 156 and 158, end 150 to connection terminal 142 and end 160 to connection terminal 144 comprise for example a single conductive track formed in a single level which is for example a level other than levels L1, L2 and L3. Generally, each of the loops of the inductors comprises at least two conductive tracks connected together over at least half the length of the loop.

[0051] [Fig. 3] is a top view of an exemplary transformer 300 according to an embodiment of the present disclosure. For example, transformer 300 is an impedance transformer.

[0052] Certain elements of [Fig. 3] correspond to elements of [Fig. 1] or [Fig. 2]. These elements are designated by the same reference and are not described again in detail.

[0053] The transformer 300 of [Fig.3] corresponds to the transformer 100 of [Fig.l] in which a conductive track 305 of the layer L1 of the loop 116 is offset relative to a conductive track 315 of the layer L3 of the loop 116.

[0054] In particular, the conductive track 305 is laterally offset so that, for any point of the loop 116, in a sectional view, the center of mass DI of the conductive track 305 is laterally offset relative to the center of mass D3 of the conductive track 315, in the sectional plane, in a direction parallel to the plane formed by the first conductive level LL. In the example of [Fig. 3], the conductive track 305 is offset towards the inside of the loop 116. According to an alternative embodiment, the conductive track 305 is offset towards the outside of the loop 116.

[0055] In the example of [Fig.3], a conductive track 325 of the layer L1 of the half-loops 146 and 148 is also offset in a similar manner to the conductive track 305 of the loop 116.

[0056] In the example of [Fig.3], none of the conductive tracks of loop 147 are offset.

[0057] In [Fig. 3], seen from above, the tracks of level L3 are fully visible, and those of level L1 are partially visible, when they are not covered by tracks of higher levels. The tracks of level L2 are, in the example of [Fig. 3], completely covered by tracks of level L3 and are not visible. The tracks connecting the connection terminals 142 and 144 to the ends 150 and 160 respectively as well as the tracks connecting the ends 156 and 158 are for example formed in a conductive level distinct from the levels L1, L2 and L3.

[0058] [Fig.4] is a partial sectional view, along an axis A3 of [Fig.3] passing through the loop 116, the half-loop 146 and the loop 147 of the transformer 300 of [Fig.3], according to an embodiment of the present description.

[0059] Certain elements of [Fig.4] correspond to elements of figures 1 to 3. These elements are designated by the same reference and are not described again in detail.

[0060] In the sectional view of [Fig. 4], the mass center D3 of the conductive track 315 of the loop 116 is laterally offset relative to the mass center DI of the conductive track 305 of the loop 116, in the sectional plane, in a direction parallel to the plane formed by the first conductor L1. The lateral displacement of the conductive track 315 relative to the conductive track 305 is indicated by an arrow F. This displacement F is for example chosen so that the conductive tracks 305 and 315 remain at least partially opposite each other, in order to allow an intermediate conductive track 310, in the layer L2, to electrically connect the conductive tracks 305 and 315.

[0061] Although an offset of an upper track relative to a lower track is described in the example of Figures 3 and 4, in other embodiments, an offset of the lower track relative to the upper track is for example performed.

[0062] Similarly, the conductive track 335 of the level L3 of the half-loop 146 has an offset according to the lateral displacement F relative to the conductive track 325 of the level L1 of the half-loop 146.

[0063] The tracks of loop 147 are for example not offset.

[0064] Track 310 of level L2 of loop 116 is for example offset to ensure the connection between the conductive tracks 305 and 315. Similarly, a track 330 of the level L2 of the half-loop 146 is for example offset to ensure the connection between the conductive tracks 325 and 335.

[0065] As described in relation to [Fig.l], the distance dl separates the conductive tracks of level L3 of the loop 116 and the half-loop 146 at the axis A3 and the distance d2 separates the conductive tracks of level L3 of the half-loop 146 and the loop 147 at the axis A3. In the example of [Fig.4], the lateral displacement F relative to the distance dl is such that the conductive tracks 305 and 335 are partially opposite.

[0066] More generally, depending on the distance separating two neighboring loops and the width of the conductive tracks forming the loops, a conductive track of the first conductive level of a loop is partially opposite or not with a track of the second conductive level of another neighboring loop. An advantage of providing partially opposite conductive tracks is that this improves, depending on the case, the compactness of the transformer and / or the magnetic coupling between the inductances.

[0067] Although in the example of Figures 3 and 4, the conductive tracks of loop 116 and each of the half-loops 146 and 148 are laterally offset, in other embodiments, it would be possible to offset the conductive tracks by only one of the half-loops or by half of one of the loops. The offset applied is for example chosen according to the desired effect on the output parameters.

[0068] [Fig.5A] is a graph representing the value (“Inductance [pH]”) of the first inductance 110 of the transformer 100, 300 of FIGS. 1 and 3 as a function of the frequency (“Frequency [GHz]”) of use of the transformer.

[0069] A first curve 500 represents the value of the inductance 110 of the transformer 100 of [Fig.l], as modeled according to a model using an equivalent diagram of the transformer 100 using a small signal approximation.

[0070] A second curve 502 represents the value of the inductance 110 of the transformer 100 of [Fig.l], obtained by carrying out a digital or electromagnetic simulation making it possible to obtain at the output of the simulation the parameters S (in English, “scattering parameters”) of the transformer.

[0071] For the comparison which follows in the figure, a numerical simulation is for example carried out assuming that the first inductance 110 is connected in parallel with a power generator, for example with a characteristic impedance of 50 Ohms, and that the second inductance 140 is connected in parallel with a power generator, for example with a characteristic impedance of 50 Ohms. The simulation makes it possible to obtain the S parameters of the transformer from which one of the parameters is extracted from the value of the inductance 110, the value of the mutual coupling parameter between the inductances 110 and 140 and the series resistance of the inductance 110. The other two parameters are obtained by using the equivalent diagram of the transformer 100 whose characteristic small signal parameters of the transformer considered are extracted from this same simulation. The same numerical simulation is replicated for the other transformers considered in this comparison.

[0072] A third curve 504 represents the value of the inductance 110 of the transformer 300 of [Fig.3], as modeled according to the model using an equivalent diagram of the transformer 100 using a small signal approximation.

[0073] A fourth curve 506 represents the value of the inductance 110 of the transformer 300 of [Fig.3], obtained by carrying out the numerical simulation.

[0074] Over a frequency range, for example between 2 and 22 GHz, the value 500 of the inductance 110 of the transformer 100 and the value 504 of the inductance 110 of the transformer 300 as modeled are similar to within 10%.

[0075] Over a frequency range, for example between 2 and 22 GHz, the value 502 of the inductance 110 of the transformer 100 and the value 506 of the inductance 110 of the transformer 300 as simulated numerically are similar to within 10%.

[0076] Over a frequency range, the value of the first inductance 110 varies little when a conductive track is offset according to the offset described in relation to FIGS. 3 and 4.

[0077] [Fig.5B] is a graph representing the value (“Inductance [pH]”) of the second inductance 140 of the transformer 100, 300 of FIGS. 1 and 3 as a function of the frequency (“Frequency [GHz]”) of use of the impedance transformer;

[0078] A first curve 510 represents the value of the inductance 140 of the transformer 100 of [Fig.l], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0079] A second curve 512 represents the value of the inductance 140 of the transformer 100 of [Fig.l], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0080] A third curve 514 represents the value of the inductance 140 of the transformer 300 of [Fig.3], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0081] A fourth curve 516 represents the value of the inductance 140 of the transformer 300 of [Fig.3], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0082] Over a frequency range, for example between 4 and 10 GHz, the value 510 of the inductance 140 of the transformer 100 and the value 514 of the inductance 140 of the transformer 300 as modeled are similar to within 10%.

[0083] Over a frequency range, for example between 4 and 10 GHz, the value 512 of the inductance 140 of the transformer 100 and the value 516 of the inductance 140 of the transformer 300 as simulated numerically are similar to within 10%.

[0084] Over a frequency range, the value of the second inductance 140 varies little when conductive tracks are offset according to the offset described in relation to FIGS. 3 and 4.

[0085] [Fig.5C] is a graph representing the value of the mutual coupling parameter (“Mutual inductance [nH]”) between the two inductances 110, 140 of the transformer 100, 300 of FIGS. 1 and 3 as a function of the frequency (“Frequency [GHz]”) of use of the impedance transformer.

[0086] A first curve 520 represents the value of the mutual coupling parameter between the two inductances 110 and 140 of the transformer 100 of [Fig.l], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0087] A second curve 522 represents the value of the mutual coupling parameter between the two inductances 110 and 140 of the transformer 100 of [Fig.l], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0088] A third curve 524 represents the value of the mutual coupling parameter between the two inductances 110 and 140 of the transformer 300 of [Fig.3], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0089] A fourth curve 526 represents the value of the mutual coupling parameter between the two inductances 110 and 140 of the transformer 300 of [Fig.3], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0090] Over a frequency range, for example between a few MHz and 20 GHz, according to the modeling, the value of the mutual coupling parameter 524 of the transformer 300 having offset conductive tracks is greater, in absolute value, than the value of the mutual coupling parameter 520 of the transformer 100 not having an offset conductive track. For example, for a frequency of 6 GHz, the mutual coupling parameter increases by approximately 7% when conductive tracks are offset.

[0091] Over a frequency range, for example between a few MHz and 20 GHz, according to the numerical simulation, the value of the mutual coupling parameter 526 of the transformer 300 having offset conductive tracks is greater, in absolute value, than the value of the mutual coupling parameter 522 of the transformer 100 not having an offset conductive track. For example, for a frequency of 6 GHz, the mutual coupling parameter increases by approximately 10% when conductive tracks are offset.

[0092] Over a frequency range, the value of the mutual coupling parameter increases when conductive tracks are offset by the offset described in relation to Figures 3 and 4.

[0093] [Fig.5D] is a graph representing the series resistance (“Resistance [Q]”) of the first inductance 110 of the transformer 100, 300 of FIGS. 1 and 3 as a function of the frequency (“Frequency [GHz]”) of use of the impedance transformer. The resistance in series with the inductances of an impedance transformer causes losses in the system and impacts the matching performance, so it is desirable to minimize this value.

[0094] A first curve 530 represents the series resistance of the inductor 110 of the transformer 100 of [Fig.l], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0095] A second curve 532 represents the series resistance of the inductance 110 of the transformer 100 of [Fig.l], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0096] A third curve 534 represents the series resistance of the inductor 110 of the transformer 300 of [Fig.3], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0097] A fourth curve 536 represents the series resistance of the inductance 110 of the transformer 300 of [Fig.3], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0098] Over a frequency range, for example between a few MHz and 10 GHz, according to the modeling, the series resistance 534 of the inductance 110 of the transformer 300 is su greater than the value 530 of the inductance 110 of the transformer 100. For example, for a frequency of 6GHz, the resistance is about 7% higher when conductive traces are offset.

[0099] Over a frequency range, for example between a few MHz and 10 GHz, according to the modeling, the series resistance 536 of the inductance 110 of the transformer 300 is greater than the value 532 of the inductance 110 of the transformer 100. For example, for a frequency of 6 GHz, the resistance is approximately 8% higher when conductive tracks are offset.

[0100] Over a frequency range, the series resistance of the first inductor 110 increases slightly and is very little modified when a conductive track is offset according to the offset described in relation to Figures 3 and 4.

[0101] [Fig.5E] is a graph representing the series resistance (“Resistance [Q]”) of the second inductance 140 of the transformer 100, 300 of FIGS. 1 and 3 as a function of the frequency (“Frequency [GHz]”) of use of the impedance transformer.

[0102] A first curve 540 represents the series resistance of the inductor 140 of the transformer 100 of [Fig.l], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0103] A second curve 542 represents the series resistance of the inductance 140 of the transformer 100 of [Fig.l], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0104] A third curve 544 represents the series resistance of the inductor 140 of the transformer 300 of [Fig.3], as modeled according to a model using an equivalent diagram of the transformer 100 using the small signal approximation.

[0105] A fourth curve 546 represents the series resistance of the inductance 140 of the transformer 300 of [Fig.3], obtained by carrying out the numerical simulation described in relation to [Fig.5A].

[0106] Over a frequency range, for example between a few MHz and 10 GHz, according to the modeling, the series resistance 544 of the inductance 140 of the transformer 300 is greater than the value 540 of the inductance 140 of the transformer 100. For example, for a frequency of 6 GHz, the series resistance is approximately 5% higher when conductive tracks are offset.

[0107] Over a frequency range, for example between a few MHz and 10 GHz, according to the modeling, the series resistance 546 of the inductance 140 of the impedance transformer 300 is greater than the value 542 of the inductance 140 of the impedance transformer 100. For example, for a frequency of 6 GHz, the series resistance is approximately 8% higher when conductive tracks are offset.

[0108] Over a frequency range, the value of the series resistance of the second inductor 140 is very little modified when a conductive track is shifted according to the offset described in relation to Figures 3 and 4.

[0109] In addition to the results described in Figures 5A to 5E resulting from the offset of conductive tracks in a transformer, the capacitive coupling between the two inductors 110 and 140 of the transformer 300 of [Fig. 3] is approximately 100% greater than the capacitive coupling of the transformer 100 of [Fig. 1].

[0110] Figures 6A to 6C are graphs obtained using the numerical simulation described in relation to [Fig.5A] with the transformer 100 of [Fig.1] and with the transformer 300 of [Fig.3]. A first capacitance and a second capacitance are added in parallel with each of the inductances 110 and 140 of the transformer 300. A first capacitance and a second capacitance having the same values ​​are added in parallel with each of the inductances 110 and 140 of the transformer 100. The values ​​of the first and second capacitances used in the simulation are adjusted according to the frequency of use of the transformer to optimize the power adaptation of the transformer studied.In Figures 6A to 6C are represented reflection coefficients S11 presented by the primary circuit of the transformer comprising the first capacitance and the inductance 110 and S22 presented by the secondary circuit of the transformer comprising the second capacitance and the inductance 140 characterizing the proportion of the reflected power between the circuit considered and what is connected to it. When designing a transformer, it is desirable that the parameters S11 and S22 are relatively low which means the reflected power at the transformer is relatively low and preferably minimal. A third parameter, S21 is represented in Figures 6A to 6C. This is the power gain or losses of the transformer 100, 300 studied.When designing a transformer, it is desirable that S21 is close to 1, i.e. close to OdB which indicates that the losses relative to the transformer in the environment considered are low and that the power transmitted through the transformer is increased.

[0111] [Fig.6A] is a graph representing the parameters S: S1, S22 and S21 of the transmission of the signal by the impedance transformers 100, 300 of figures 1 and 3 at a frequency of 25GHz.

[0112] In the example of [Fig.6A], the first and second capacities used for the numerical simulation have the value 150fF and 120fF.

[0113] Curve 600 represents the amplitude (“Magnitude [dB]”) of the SI coefficient 1 in decibels of transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0114] Curve 602 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0115] Curve 604 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0116] Curve 606 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0117] Curve 608 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0118] Curve 609 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0119] For a frequency of 25GHz, the SI 1 coefficient is approximately -38dB for the 300 transformer against -16dB for the 100 transformer.

[0120] For a frequency of 25GHz, the S22 coefficient is approximately -33dB for the 300 transformer against -16dB for the 100 transformer.

[0121] For a frequency of 25GHz, the coefficient S21 is approximately -LldB for the 300 transformer against -1.3dB for the 100 transformer.

[0122] For a frequency of 25GHz, for the transformer 300 comprising offset conductive tracks as described in relation to Figures 3 and 4, the coefficients S1 and S22 are lower and the coefficient S21 is closer to 0 than for the transformer 100 of [Fig.l].

[0123] [Fig.6B] is a graph representing the parameters S: S1, S22 and S21 of the transmission of the signal by the impedance transformers 100, 300 of figures 1 and 3 at a frequency of 20GHz.

[0124] In the example of [Fig.6B], the first and second capacities used for the numerical simulation have the values ​​245fF and 169fF.

[0125] Curve 610 represents the amplitude (“Magnitude [dB]”) of the SI coefficient 1 in decibels of transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0126] Curve 612 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0127] Curve 614 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0128] Curve 616 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0129] Curve 618 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0130] Curve 619 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0131] For a frequency of 20GHz, the SI 1 coefficient is approximately -23dB for the 300 transformer against -16dB for the 100 transformer.

[0132] For a frequency of 20GHz, the S22 coefficient is approximately -17dB for the 300 transformer against -13dB for the 100 transformer.

[0133] For a frequency of 20GHz, the S21 coefficient is approximately -1.3dB for the 300 transformer versus -1.5dB for the 100 transformer.

[0134] For a frequency of 20GHz, for the transformer 300 comprising offset conductive tracks as described in relation to Figures 3 and 4, the coefficients S1 and S2 are lower and the coefficient S2 is closer to 0 than for the transformer 100 of [Fig.l].

[0135] [Fig.6C] is a graph representing the parameters S: S1, S22 and S21 of the transmission of the signal by the impedance transformers 100, 300 of figures 1 and 3 at a frequency of 42GHz.

[0136] The first and second capacitors used for the numerical simulation have the values ​​80fF and 40fF.

[0137] Curve 620 represents the amplitude (“Magnitude [dB]”) of the SI coefficient 1 in decibels of transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0138] Curve 622 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0139] Curve 624 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0140] Curve 626 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0141] Curve 628 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 100 of [Fig.l] as a function of the operating frequency (“Frequency [GHz]”).

[0142] Curve 629 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of transformer 300 of [Fig.3] as a function of the operating frequency (“Frequency [GHz]”).

[0143] For a frequency of 42GHz, the SI coefficient 1 is approximately -18dB for the 300 transformer against -10dB for the 100 transformer.

[0144] For a frequency of 42GHz, the S22 coefficient is approximately -44dB for the 300 transformer against -12dB for the 100 transformer.

[0145] For a frequency of 42GHz, the S21 coefficient is approximately -1.ldB for the 300 transformer against -1.5dB for the 100 transformer.

[0146] For a frequency of 42GHz, for the transformer 300 comprising offset conductive tracks as described in relation to Figures 3 and 4, the coefficients S1 and S2 are lower and the coefficient S2 is closer to 0 than for the transformer 100 of [Fig.l].

[0147] [Fig.7A] is a top view of an exemplary transformer 700 according to an embodiment of the present disclosure. For example, transformer 700 is an impedance transformer.

[0148] [Fig.7B] and [Fig.7C] are top views of a first inductor 710 and a second inductor 740 of the transformer 700 of [Fig.7A].

[0149] According to one embodiment, the first inductor 710 is connected to a first external electronic circuit (not shown in FIGS. 7A to 7C) and the second inductor 740 is connected to a second external electronic circuit (not shown in FIGS. 7A to 7C).

[0150] The transformer 700 comprises the first external inductor 710. The inductor 710 comprises two connection terminals, for example an input / output terminal 712 and an input / output terminal 714. The inductor 710, as shown in the example of [Fig.7A] and [Fig.7B], comprises two loops: a first loop formed of a first half-loop 716 and a second half-loop 718 and a second loop 717 so that an electric current passing through the inductor 710 from its terminal 712 to its terminal 714 passes in order through the half-loop 716 then the loop 717 then the half-loop 718. The first half-loop 716 connects one end 719 to one end 720. The end 719 is for example connected to the connection terminal 712 by one or more conductive tracks. The second 717 connects an end 722 to an end 728. The end 722 is for example connected to the end 720 by one or more conductive tracks.The second half-loop 718 connects an end 730 to an end 732. The end 730 is for example connected to the end 728 by one or more conductive tracks and / or one or more vias. The end 732 is for example connected to the connection terminal 714 by one or more conductive tracks.

[0151] The transformer 700 comprises the second internal inductor 740. The inductor 740 comprises two connection terminals, for example an input / output terminal 742 and an input / output terminal 744. The inductor 740, as shown in the example of [Fig.7A] and [Fig.7C], comprises three loops: a first loop formed of a first half-loop 746 and a second half-loop 750, a second loop formed of a first half-loop 747 and a second half-loop 749 and a third loop 748. An electric current passing through the inductor 740 from its terminal 742 to its terminal 744 passes in order through the half-loop 746 then the half-loop 747 then the loop 748 then the half-loop 749 then the half-loop 750.

[0152] The first half-loop 746 of the first loop connects an end 752 to an end 754. The end 752 is for example connected to the connection terminal 742 by one or more conductive tracks and / or one or more vias. The first half-loop 747 of the second loop connects an end 756 to an end 758. The end 756 is for example connected to the end 754 by one or more conductive tracks and / or one or more vias. The third loop 748 connects an end 760 to an end 762. The end 760 is for example connected to the end 758 by one or more conductive tracks and / or one or more vias. The end 762 is for example the junction between the half-loops 748 and 749. The second half-loop 749 of the second loop connects an end 762 to an end 764. The second half-loop 750 of the first loop connects an end 766 to an end 768.The end 766 is for example connected to the end 764 by one or more conductive tracks and / or one or more vias. The end 768 is for example connected to the connection terminal 744 by one or more conductive tracks and / or one or more vias.

[0153] Compared to the examples of Figures 1 and 3, in the example of [Fig.7A], the loops are substantially octagonal in shape instead of being substantially rectangular. In other embodiments, other loop shapes are possible.

[0154] In the example of transformer 700 of [Fig.7A], the loops of inductors 710 and 740 are each formed from a stack of three conductive tracks distributed in levels L1, L2 and L3 according to the arrangement described in relation to [Fig.4]. In particular, loop 717, loop 748 and each of the half-loops 716, 718, 746, 747, 749 and 750 comprise conductive tracks in levels L1, L2 and L3 connected together over the entire length of the loop. The conductive tracks connecting the ends 758 and 760, 764 and 766, the end 752 to the connection terminal 742 and the end 768 to the connection terminal 744 comprise for example a single conductive track formed in a single level which is for example a level other than the levels L1, L2 and L3.The conductive tracks connecting the ends 754 and 756 comprise for example a single conductive track formed in a single level which is for example the level LL. Generally speaking, each of the loops of the inductances. comprise at least two conductive tracks connected together over at least half the length of the loop.

[0155] The transformer 300 of [Fig.3] corresponds to the transformer 100 of [Fig.l] in which the conductive track 205 of the loop 116 is offset relative to the conductive track 215 of the loop 116.

[0156] Still with reference to the example of the transformer 700, the conductive tracks of the level L1 of the loop 717, the loop 748 and each of the half-loops 716, 718, 746, 747, 749 and 750 are laterally offset so that, at any point, in a sectional view, the centers of mass of the conductive tracks of the level L3 are laterally offset relative to the centers of mass of the conductive tracks of the level L1, in the sectional plane, in a direction parallel to the plane formed by the first conductive level L1. In this example, the conductive tracks of the level L3 are offset towards the outside of the inductances 710, 740. According to an alternative embodiment, the conductive tracks of the level L3 are offset towards the inside of the inductances 710, 740. The direction of the offset will be chosen according to the desired performance.

[0157] In Figures 7A to 7C, seen from above, the tracks of level L3 are fully visible, and those of level L1 are partially visible, when they are not covered by tracks of higher levels. The tracks of level L2 are, in the example of Figures 7A to 7C, completely covered by tracks of level L3 and are not visible.

[0158] Figures 8A to 8C are graphs obtained using the numerical simulation described in relation to [Fig.5A] with the transformer 700 of [Fig.7A] and with a second transformer similar to the transformer 700 but not having an offset between conductive tracks of the same loop. In the example of [Fig.8A], the capacitances are removed from the circuit used for the simulation. In the example of Figures 8B and 8C, the values ​​of the first and second capacitances used in the simulation are adjusted according to the frequency of use of the transformer to optimize the power adaptation and the power transfer of the transformer studied.In Figures 8A to 8C are represented reflection coefficients S11 presented by the primary circuit of the transformer comprising the first capacitance and the inductance 110 and S22 presented by the secondary circuit of the transformer comprising the second capacitance and the inductance 140 characterizing the proportion of the power reflected between the circuit considered and what is connected to it. When designing a transformer, it is desirable that the parameters S11 and S22 are as low as possible which means that the power reflected at the transformer is reduced and preferably minimal. A third parameter, S21 is represented in Figures 8A to 8C. This is the power gain or losses of the . transformer studied. When designing a transformer, it is desirable that S21 is as close to 1 as possible, or as close to OdB as possible, which indicates that the losses relative to the transformer in the environment considered are low and the power transmitted through the transformer is increased.

[0159] [Fig.8A] is a graph representing the parameters S: SI 1, S22 and S21 of the signal transmission by the transformer 700 of [Fig.7A] and the quality parameters SI 1, S22 and S21 of the second transformer at a frequency of 12GHz.

[0160] Curve 800 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0161] Curve 802 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0162] Curve 804 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0163] Curve 806 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0164] Curve 808 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0165] Curve 809 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0166] For a frequency of 12GHz, without using external capacities to the impedance transformers during the simulation, the SU coefficient is approximately -17dB for the 700 transformer against -10dB for the second transformer.

[0167] The coefficient S22 is approximately -16dB for the 700 transformer against -9dB for the second transformer.

[0168] The coefficient S21 is approximately -1.3dB for the 700 transformer against -1.7dB for the second transformer.

[0169] For a frequency of 12GHz, for the transformer 700 comprising conductive tracks offset as described in relation to figures 3 and 4, the coefficients S1 and S2 are lower and the coefficient S21 is closer to 0 than for the second transformer.

[0170] [Fig.8B] is a graph representing the parameters S: S1, S22 and S21 of the signal transmission by the transformer 700 of [Fig.7A] and the parameters of SI 1, S22 and S21 quality of the second transformer at a frequency of 9GHz.

[0171] In the example of [Fig.6B], the first and second capacities used for the numerical simulation have the values ​​140fF and 60fF.

[0172] Curve 810 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0173] Curve 812 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0174] Curve 814 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0175] Curve 816 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0176] Curve 818 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0177] Curve 819 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0178] For a frequency of 9GHz, the SI 1 coefficient is approximately -23dB for the trans 700 trainer vs -15dB for the second transformer.

[0179] The coefficient S22 is approximately -33dB for the 700 transformer against -15dB for the second transformer.

[0180] The coefficient S21 is approximately -1.3dB for the 1st 700 transformer versus -1.2dB for the second impedance transformer.

[0181] For a frequency of 9GHz, for the transformer 700 comprising offset conductive tracks as described in relation to Figures 3 and 4, the coefficients S1 and S2 are lower and the coefficient S21 is closer to 0 than for the second transformer.

[0182] [Fig.8C] is a graph representing the parameters S: SI 1, S22 and S21 of the signal transmission by the transformer 700 of [Fig.7A] and the quality parameters SI 1, S22 and S21 of the second transformer at a frequency of 13GHz.

[0183] The first capacitance used for the numerical simulation has a value of 60fF and the second capacitance is not connected.

[0184] Curve 820 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0185] Curve 822 represents the amplitude (“Magnitude [dB]”) of the SI 1 coefficient in decibels of transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0186] Curve 824 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0187] Curve 826 represents the amplitude (“Magnitude [dB]”) of the coefficient S22 in decibels of the transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0188] Curve 828 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the second transformer as a function of the operating frequency (“Frequency [GHz]”).

[0189] Curve 829 represents the amplitude (“Magnitude [dB]”) of the coefficient S21 in decibels of the transformer 700 of [Fig.7A] as a function of the operating frequency (“Frequency [GHz]”).

[0190] For a frequency of 12.7GHz, the SI 1 coefficient is approximately -27dB for the 700 transformer versus -12dB for the second impedance transformer.

[0191] The coefficient S22 is approximately -44dB for the 700 transformer versus -12dB for the second impedance transformer.

[0192] The coefficient S21 is approximately -LldB for the 700 transformer against -1.5dB for the second transformer.

[0193] For a frequency of 12.7 GHz, for the transformer 700 comprising offset conductive tracks as described in relation to Figures 3 and 4, the coefficients S1 and S2 are lower and the coefficient S21 is closer to 0 than for the second transformer.

[0194] [Fig.9] is a partial sectional view of the transformer of [Fig.1] according to an example other than that of [Fig.2] and according to an embodiment of the present description.

[0195] Certain elements of [Fig.9] correspond to elements of figures 1 to 4. These elements are designated by the same reference and are not described again in detail.

[0196] [Fig. 9] represents an alternative to [Fig. 2]. Instead of an offset between the conductive tracks 305 of the layer L1 and 315 of the layer L3 of the transformer 300 as described in relation to FIGS. 3 and 4, in the example of [Fig. 9], the offset is for example made between conductive tracks 905 of the layer L1 and 910 of the layer L2 of the loop 116.

[0197] The conductive track 910, for example formed by one or more conductive vias, is laterally offset so that, for any point of the loop 116, in a sectional view, the center of mass E2 of the conductive track 910 is laterally offset relative to the center of mass El of the conductive track 905, in the sectional plane, in a direction parallel to the plane formed by the first conductive level LE. The offset is represented by an arrow F'.

[0198] An example of a manufacturing method is detailed below for the transformer 100 of FIGS. 1 and 9. Similar methods are for example used for the manufacturing of the transformer 300 of [Fig. 3] and 700 of [Fig. 7A].

[0199] The method comprises for example: - a step of forming in a first level L1 a structure, of the conductive track 905 of the loop 116, of the inductance 110, - a step of forming in a second level L2 of the structure, one or more vias forming the conductive track 910 of the loop 116; - a step of forming in a third level L3 of the structure, the conductive track 915 of the loop 116, the conductive tracks 905, 910 and 915 being electrically connected to each other directly over at least half, or approximately half, of the length of the loop 116. Over at least half, or about half, of the length of the loop 116, the conductive tracks 905 and 910 are arranged so that, in a sectional view perpendicular to the length of the loop 116, the center of mass E1 of the conductive track 905 is laterally offset from the center of mass E2 of the conductive track 910 in the sectional plane, and in a direction parallel to the plane formed by the level LL

[0200] In other embodiments, for the transformer 300 of Figures 3 and 4, over at least half the length of the loop 116, the conductive tracks 305 and 315 are arranged so that, in a sectional view perpendicular to the length of the loop 116, the center of mass DI of the conductive track 305 is laterally offset relative to the center of mass D3 of the conductive track 315 in the sectional plane, and in a direction parallel to the plane formed by the level LL

[0201] According to the embodiments described, the offset between two conductive tracks of a loop of an inductance of a transformer makes it possible to increase the mutual coupling between the inductances as well as the capacitive coupling and to improve the reflection and transmission gain coefficients of the transformer. The increase in the capacitive coupling makes it possible to reduce the value or eliminate external capacitances to the transformer in the electronic circuits concerned. This improves the compactness of the transformer.

[0202] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and Variants could be combined, and other variations will occur to those skilled in the art. In particular, examples of configurations of impedance transformers 300, 700 have been shown, but the inductors and loops may have other shapes and arrangements. A lateral offset of a track 205 toward the outside of the loop 116 has been illustrated, but an offset toward the inside of the loop is also possible. The loops of the illustrated impedance transformers 100, 300, 700 comprise three conductive tracks connected over at least half the length of the loop. A greater number of conductive tracks is also possible.

Claims

Claims

1. Transformer (100, 300, 700) comprising, in a laminated structure, a first inductor (110, 710) and a second inductor (140, 740), the first inductor comprising: - a first loop (116, 716-718) comprising a first conductive track (305, 905) in a first level (L1) of the structure and a second conductive track (315, 910) in a second level (L3, L2) of the structure, the first and second conductive tracks being adapted to be electrically connected to each other directly, or by an intermediate conductive track (910), over at least half the length of the first loop;wherein, over at least half the length of the first loop, the first and second conductive tracks are arranged so that, in a sectional view perpendicular to the length of the first loop, the center of mass (Dl, El) of the first conductive track is laterally offset from the center of mass (D2, E3) of the second conductive track in the sectional plane, and in a direction parallel to the plane formed by the first level.;

2. The transformer (300, 700) of claim 1, wherein the first (305) and second (315) conductive tracks are connected to each other by the intermediate conductive track (310), the intermediate conductive track comprising one or more vias.

3. The transformer (100) of claim 1, the first loop (116, 716-718) further comprising a third conductive track (915) electrically connected to the second conductive track over at least half the length of the first loop, wherein the second conductive track (910) comprises one or more vias connecting the first conductive track (905) to the third conductive track (915).

4. A transformer (100, 300, 700) according to any one of claims 1 to 3, wherein the second inductor (140, 740) comprises a first loop (146-148, 747 and 749) comprising a fourth conductive track (225, 325) in the first level (L1) of the structure and a fifth conductive track (230, 235, 330, 335) in the second level (L2, L3) of the structure.

5. Transformer (100, 300, 700) according to claim 4, wherein the first conductive track (305) of the first loop (116, 716-718) of the first inductor (110, 710) in the first level (L1) is at

6.

7.

8. less partially opposite the fifth track (330, 335) of the first loop (146-148, 747-749) of the second inductor (140, 740) in the second level (L2). A method of manufacturing a transformer (100, 300, 700) comprising, in a laminated structure, a first inductor (110, 710) and a second inductor (140, 740), the method comprising: - the formation, in a first level of the structure (L1), of a first conductive track (305, 905) of a first loop (116, 716-718) of a first inductance (110, 710); - the formation, in a second level of the structure (L2), of a second conductive track (315, 910) of the first loop (116, 716-718), the first and second conductive tracks being adapted to be electrically connected to each other directly, or by an intermediate conductive track (910), over at least half the length of the first loop (116, 716-718); wherein, over at least half the length of the first loop, the first and second conductive tracks are arranged so that, in a sectional view perpendicular to the length of the first loop, the center of mass (Dl, El) of the first conductive track is laterally offset from the center of mass (D3, E2) of the second conductive track in the sectional plane, and in a direction parallel to the plane formed by the first level (Ll). The method of claim 6, wherein the first (305) and second (315) conductive tracks are connected to each other by the intermediate conductive track (310), the method further comprising, after forming the first conductive track and before forming the second conductive track, forming at least one via forming the intermediate conductive track on the first conductive track, the second conductive track being formed on the at least one via such that the first and second conductive tracks are electrically connected to each other via the at least one via. The method of claim 6, wherein the second conductive track (910) comprises one or more vias, the method further comprising, after forming the second conductive track (910), forming a third conductive track (915) on the second conductive track, the third conductive track being electrically connected to the second conductive track on at least half the length of the first loop (116, 716-718).

9. Method according to any one of claims 6 to 8, further comprising: - forming, in the first level (L1) of the structure, a fourth conductive track (325) of a first loop (146-148, 747-749) of the second inductance (140, 740); - forming, in the second level (L2) of the structure, a fifth conductive track (330, 335) of the first loop (146-148, 747-749) of the second inductance (140, 740).

10. The method of claim 9, wherein the fifth track (330, 335) of the first loop (146-148, 747-749) in the second level (L2) is formed such that the first conductive track (305) of the first loop (116, 716-718) in the first level (L1) is at least partially opposite the fifth track (330, 335) of the first loop (146-148, 747-749) in the second level (L2).

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