Integrated coupling device, in particular of the 90° hybrid type

Abstract

A 90° hybrid inductive-capacitive coupling stage includes two first stage terminals capable of forming two stage inputs or two stage outputs and two second stage terminals capable of respectively forming two stage outputs or two stage inputs. The coupling stage is advantageously modular having a first stage axis of symmetry and a second stage axis of symmetry orthogonal to each other with neighboring inductive metal tracks being overlaid in at least one crossing region to form both an inductive circuit and a capacitive circuit. The metal tracks are coupled to the first stage terminals and to the second stage terminals such that the two first stage terminals are situated on one side of the first stage axis of symmetry and the two second stage terminals are situated on the other side of the first stage axis of symmetry.

Claims

1. A hybrid inductive-capacitive coupling stage, comprising: a first input coupled to receive an input signal; a second input coupled to a load having an impedance that is connected to ground; a first output; a second output; wherein the first and second outputs are configured to deliver first and second output signals, respectively, from the input signal that phase-shifted by 90° with respect to each other; a first metal track extending for a first length from a first end, which is coupled to receive the input signal from said first input, to a second end; a second metal track inductively coupled to and extending parallel and adjacent to the first metal track for said first length from a first end, which is coupled to deliver the first output signal to said first output, to a second end; a third metal track extending for a second length from a first end, which is coupled to the impedance at said second input, to a second end; a fourth metal track inductively coupled to and extending parallel and adjacent to the third metal track for said second length from a first end, which is coupled to deliver the second output signal to said second output, to a second end; wherein said first and second lengths for the first, second, third and fourth metal tracks extend parallel to a first axis of symmetry, with said first and third metal tracks on one side of said first axis of symmetry and said second and fourth metal tracks on an opposite side of said first axis of symmetry; a fifth metal track extending between the second end of the first metal track and the second end of the fourth metal track; a sixth metal track extending between the second end of the second track and the second end of the third metal track; wherein the first and sixth metal tracks are insulated from each other and overlaid in a crossing region to provide a capacitive coupling; wherein lengths of the fifth and sixth metal tracks are aligned with a second axis of symmetry, said second axis of symmetry being perpendicular to said first axis of symmetry; and wherein the first and second metal tracks are on one side of the second axis of symmetry and the third and fourth metal tracks are on an opposite side of the second axis of symmetry.

2. The stage as claimed in claim 1, wherein the first and second lengths are identical.

3. The stage as claimed in claim 1, further comprising an adjustment capacitor having a first terminal directly connected to the second end of the first metal track at the fifth metal track and a second terminal directly connected to the second end of the third metal track at the sixth metal track.

4. A hybrid inductive-capacitive coupling stage, comprising: a first input coupled to receive a first input signal; a second input coupled to receive a second input signal; wherein the first and second input signals are phase-shifted by 90° with respect to each other; a first output configured to deliver an output signal comprising a sum of the first and second input signals; a second output coupled to a load having an impedance that is connected to ground; a first metal track extending for a first length from a first end, which is coupled to receive the first input signal from said first input, to a second end; a second metal track inductively coupled to and extending parallel and adjacent to the first metal track for said first length from a first end, which is coupled to deliver the output signal to said first output, to a second end; a third metal track extending for a second length from a first end, which is coupled to receive the second input signal from said second input, to a second end; a fourth metal track inductively coupled to and extending parallel and adjacent to the third metal track for said second length from a first end, which is coupled to the impedance at said second output, to a second end; wherein said first and second lengths for the first, second, third and fourth metal tracks extend parallel to a first axis of symmetry, with said first and third metal tracks on one side of said first axis of symmetry and said second and fourth metal tracks on an opposite side of said first axis of symmetry; a fifth metal track extending between the second end of the first metal track and the second end of the fourth metal track; a sixth metal track extending between the second end of the second track and the second end of the third metal track; wherein the first and sixth metal tracks are insulated from each other and overlaid in a crossing region to provide a capacitive coupling; wherein lengths of the fifth and sixth metal tracks are aligned with a second axis of symmetry, said second axis of symmetry being perpendicular to said first axis of symmetry; and wherein the first and second metal tracks are on one side of the second axis of symmetry and the third and fourth metal tracks are on an opposite side of the second axis of symmetry.

5. The stage as claimed in claim 3, wherein the first and second lengths are identical.

6. The stage as claimed in claim 3, further comprising an adjustment capacitor having a first terminal directly connected to the second end of the first metal track at the fifth metal track and a second terminal directly connected to the second end of the third metal track at the sixth metal track.

7. A hybrid inductive-capacitive coupling stage, comprising: a first terminal coupled to a first load having a first impedance that is connected to ground; a second terminal coupled to a second load having a second impedance that is connected to ground; a third terminal coupled to receive an input signal; a fourth terminal coupled to generate an output signal that is phase shifted relative to the input signal; a first metal track extending for a first length from a first end coupled to said first terminal to a second end; a second metal track inductively coupled to and extending parallel and adjacent to the first metal track for said first length from a first end coupled to said third terminal to a second end; a third metal track extending for a second length from a first end coupled to said second terminal to a second end; a fourth metal track inductively coupled to and extending parallel and adjacent to the third metal track for said second length from a first end coupled to said fourth terminal to a second end; wherein said first and second lengths for the first, second, third and fourth metal tracks extend parallel to a first axis of symmetry, with said first and third metal tracks on one side of said first axis of symmetry and said second and fourth metal tracks on an opposite side of said first axis of symmetry; a fifth metal track extending between the second end of the first metal track and the second end of the fourth metal track; a sixth metal track extending between the second end of the second track and the second end of the third metal track; wherein the first and sixth metal tracks are insulated from each other and overlaid in a crossing region to provide a capacitive coupling; wherein lengths of the fifth and sixth metal tracks are aligned with a second axis of symmetry, said second axis of symmetry being perpendicular to said first axis of symmetry; and wherein the first and second metal tracks are on one side of the second axis of symmetry and the third and fourth metal tracks are on an opposite side of the second axis of symmetry.

8. The stage as claimed in claim 7, wherein the first and second lengths are identical.

9. The stage as claimed in claim 7, further comprising an adjustment capacitor having a first terminal directly connected to the second end of the first metal track at the fifth metal track and a second terminal directly connected to the second end of the third metal track at the sixth metal track.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages and features of the invention will become apparent upon examining the detailed description of embodiments, which are in no way limiting, and from the appended drawings in which:

(2) FIG. 1 illustrates one example of a coupling device implemented in an integrated circuit on silicon;

(3) FIG. 2 illustrates a divider mode of operation;

(4) FIG. 3 illustrates a combiner mode of operation;

(5) FIG. 4 illustrates one example of a first topology of the coupling stage;

(6) FIG. 5 is a perspective view of FIG. 4;

(7) FIG. 6 illustrates a series coupling of modules;

(8) FIGS. 7-10 illustrate other embodiments of a coupling stage;

(9) FIG. 11 illustrates schematically a wireless communications device; and

(10) FIG. 12 illustrates an example of a coupling stage used in a phase-shift device.

DETAILED DESCRIPTION

(11) FIG. 1 illustrates one example of a coupling device DC implemented in an integrated circuit CI on silicon.

(12) Said coupling device DC here comprises a coupling stage EC of the 90° hybrid type.

(13) In other words, the coupling stage EC can operate according to two different modes: a divider mode DIV and a combiner mode COMB. Said coupling stage EC comprises two first stage terminals BE11 and BE12 and two second stage terminals BE21 and BE22.

(14) In the divider mode DIV illustrated in FIG. 2, one of the two first stage terminals BE11 receives an input signal IN_div and the other of the two first stage terminals BE12 is coupled to a load CHG50 having a fixed impedance, typically 50 ohms, itself connected to ground. The two second stage terminals BE21 and BE22, in this divider mode DIV, each deliver an output signal OUT_div1 and OUT_div2. In theory, these two output signals OUT_div1 and OUT_div2 are phase-shifted by 90°. Each of the two output signals OUT_div1 and OUT_div2 has a power equal to half of the power of the input signal IN_div.

(15) With regard to the combiner mode COMB illustrated in FIG. 3, the two second stage terminals BE21 and BE22 are each used to receive an input signal IN_comb1 and IN_comb2. The two input signals IN_comb1 and IN_comb2 are ideally phase-shifted by 90° with respect to each other. One of the two first terminals BE11 delivers an output signal OUT_comb and the other of the two first terminals BE12 is coupled to said load CHG50, having a fixed impedance, typically 50 ohms, and connected to ground. In theory, the power of the output signal OUT_comb is equal to the sum of the powers of the two input signals IN_comb1 and IN_comb2.

(16) As can be seen in FIGS. 2 and 3, the two first stage terminals BE11 and BE12 and the two second stage terminals BE21 and BE22 are respectively situated on the same side of said stage EC. This feature advantageously allows a coupling in parallel between said coupling stage EC and components coupled to said stage, for example power amplifiers which will be described in more detail hereinafter in the description. For this reason, the space required by the coupling stage EC and components coupled to said stage can be considerably reduced.

(17) The coupling stage EC may advantageously be modular. In other words, the coupling stage EC may comprise one or more modules, which may be configured according to the desired overall inductive and capacitive value and/or the desired size of said coupling device.

(18) The coupling stage EC furthermore comprises metal tracks being overlaid in at least one crossing region so as to allow the input terminals in combiner mode COMB and the output terminals in divider mode DIV situated in the same side of said device to be obtained.

(19) Reference is now made to FIG. 4 in order to illustrate one example of a first topology of the coupling stage EC.

(20) The coupling stage EC here comprises a first module MOD1 comprising a first module axis of symmetry ASM1 and a second module axis of symmetry ASM2. Said second module axis of symmetry ASM2 is orthogonal to the first module axis of symmetry ASM1.

(21) The first module MOD1 further comprises two first neighboring inductive metal tracks PM11 and PM12 situated, in part, on either side of the two module axes of symmetry ASM1 and ASM2 of the first module MOD1 and a crossing region RC in which the two metal tracks PM11 and PM12 are overlaid along the second module axis of symmetry ASM2.

(22) Two ends E1 and E2 of the two first metal tracks PM11 and PM12 situated on one side of the first axis of symmetry ASM1 form two first module terminals BM11 and BM12. Two other ends E3 and E4 of the two first metal tracks PM11 and PM12 situated on the other side of the first axis of symmetry ASM1 form two second module terminals BM21 and BM22. The two first metal tracks PM11 and PM12 form both a first inductive circuit CD and a first capacitive circuit CC1. The two first module terminals BM11 and BM12 are coupled to the two first stage terminals BE11 and BE12 and the two second module terminals BM21 and BM22 are respectively coupled to the two second stage terminals BE21 and BE22.

(23) For this reason, the coupling stage EC is indeed symmetrical with respect to a first stage axis of symmetry ASE1 parallel to the first module axis of symmetry ASM1. The coupling stage EC is also symmetrical with respect to a second stage axis of symmetry ASE2 parallel to the second module axis of symmetry ASM2.

(24) In the case of a coupling stage EC comprising only one first module MOD1, said first and second stage axes of symmetry ASE1 and ASE2 are indeed respectively superposed onto said first and second module axes of symmetry ASM1 and ASM2.

(25) The two first stage terminals BE11 and BE12 are situated on one side of the first stage axis of symmetry ASE1, whereas the two second stage terminals BE21 and BE22 are situated on the other side of the first stage axis of symmetry ASE1.

(26) As illustrated in FIG. 5 which is a perspective view of FIG. 4, the two first stage terminals BE11 and BE12, the two second stage terminals BE21 and BE22 and one of the first metal tracks PM11 are situated in a first plane P1 of said integrated circuit CI. The other first metal track PM12 is situated in a second plane P2 different from said first plane P1 within the integrated circuit CI. It should be noted that the first and second planes P1 and P2 are advantageously located within the interconnection part (BEOL: Back End Of Line) of the integrated circuit CI and, more particularly, within the upper region of this BEOL part so as to facilitate the implementation of said coupling stage EC.

(27) The first stage terminal BE12 and the second stage terminal BE21 are coupled to the first metal track PM12 situated in the second plane P2. This topology advantageously allows said crossing region RC to be created along the second stage axis of symmetry ASE2. This crossing region RC in two levels indeed forms the majority of the capacitive value of said first module MOD1. The two first metal tracks PM11 and PM12 mainly influence the inductive value of said first module MOD1.

(28) Said first module MOD1 forms an important module of said coupling stage EC. By way of example, the first module MOD1 has a capacitive value of 12.9 fF and an inductive value of 8 pH.

(29) In order to obtain desired overall capacitive and inductive values in said coupling stage EC, several different embodiments are provided (see, FIGS. 6 to 10) and use a larger or smaller number of modules with identical or different configurations, with at least one of the modules being a first module such as illustrated in FIGS. 4 and 5.

(30) Thus, the coupling stage EC may advantageously comprise, for example, a branch B comprising an odd or even number (preferably odd) of first modules MOD1 coupled in series (FIG. 6).

(31) The first and the second module terminals BM11_i and BM21_i or BM12_i and BM22_i situated on one side of the second module axis of symmetry ASM2_i of a first module MOD1_i are respectively coupled to the first and to the second stage terminals BE12_i+1 and BE22_i+1 or BE11_i+1 or BE21_i+1 situated on the other side of the second module axis of symmetry ASM2_i+1 of another adjacent first module MOD1_i+1. The first modules MOD1_i may be directly coupled in series (FIG. 6) or else indirectly via other types of modules as illustrated in FIG. 7.

(32) In the example illustrated in FIG. 6, said branch B comprises fifteen first modules coupled in series. The first and second stage axes of symmetry ASE1 and ASE2 are respectively superposed onto the first and second axes of symmetry ASM1_8 and ASM2_8 of the eighth first module MOD1_8. In the case where the stage EC only comprises the branch B, the terminals of the first module and of the last module situated at the two ends of said branch B form the first BE11, BE12 and second terminals BE21, BE22 of said stage EC.

(33) FIG. 7 illustrates another embodiment. Said coupling stage EC here comprises a branch B_7 comprising a group G containing a first module MOD1 coupled in series between two second modules MOD2_1 and MOD2_2.

(34) The first second module MOD2_1 comprises a first module axis of symmetry ASM1_1 and two second neighboring inductive metal tracks PM21_1 and PM22_1 situated on either side of the first module axis of symmetry ASM1_1.

(35) The two second metal tracks PM21_1 and PM22_1 form both a second inductive circuit CI2_1 and a second capacitive circuit CC2_1. The inductive value of the second inductive circuit CI2_1 and the capacitive value of the second capacitive circuit CC2_1 may be adjusted by respectively modifying the length of the second metal tracks PM21_1 and PM22_1 and the interval between the second metal tracks PM21_1 and PM22_1.

(36) Furthermore, the two ends E5 and E6 of the two second metal tracks PM21_1 and PM22_1 situated on one side of the first module axis of symmetry ASM1_1 form two third module terminals BM31_1 and BM32_1, whereas the two ends (E7, E8) of the two second metal tracks PM21_1 and PM22_1 situated on the other side of the first module axis of symmetry ASM1_1 form two fourth module terminals BM41_1 and BM42_1.

(37) Furthermore, a third module terminal BM31_1 or BM32_2 of each of the two second modules MOD2_1 and MOD2_2 is coupled to a respective first stage terminal BE11 or BE12 and a fourth module terminal BM41_1 or BM42_2 of each of the two second modules MOD2_1 and MOD2_2 is coupled to a respective second stage terminal BE21 or BE22.

(38) Said second metal tracks PM21_1 and PM22_1 of said first second module MOD2_1 are therefore advantageously situated in the same first plane P1 as the first and second stage terminals BE11, BE12, BE21 and BE22.

(39) For this reason, said branch B comprising said group G can indeed individually form a 90° hybrid coupling stage EC. The first and second stage axes of symmetry ASE1 and ASE2 are superposed onto the first and second axes of symmetry of said first module ASM1 and ASM2.

(40) In other words, a coupling stage EC can be formed by using a branch B comprising one or more first modules MOD1 coupled in series and/or coupled with one or more group(s) G.

(41) By way of non-limiting example, FIG. 8 illustrates a coupling stage EC comprising a branch B_8 comprising a first module MOD1 at each end of said branch B_8 and said at least one group G coupled in series between the two first end modules MOD1_3 and MOD1_4.

(42) Said two first modules MOD1_3 and MOD1_4 are symmetrical with respect to the first axis of symmetry of the first module MOD1 of said group G. The first and second stage axes of symmetry ASE1 and ASE2 are superposed in this example onto the first and second axes of symmetry of the first module MOD1 of said group G. The terminals of said two first modules MOD1_3 and MOD1_4 situated at the ends of said branch B_8 indeed form the first BE11, BE12 and second terminals BE21, BE22 of said coupling stage EC.

(43) In a case illustrated in FIG. 9, the coupling stage EC may comprise several, here five, parallel branches B1_9 to B5_9. Each branch Bi_9 comprises a mixed combination of said first MOD1 and second modules MOD2. The coupling stage EC also comprises inductive metal connection tracks PMR1_12 to PMR1_45 and PMR2_12 to PMR2_45 parallel to the second stage axis of symmetry ASE2 coupled between both of the two neighboring parallel branches B1_9 to B5_9.

(44) It should be noted that the length of the inductive metal connection tracks PMR1_12 to PMR1_45 and PMR2_12 to PMR2_45 also influences the overall inductive value of said coupling stage EC.

(45) A fine adjustment of the overall capacitive value of said coupling stage EC is possible (FIGS. 8 and 9) by connecting at least one adjustment capacitor CA in parallel onto the superposed parts of the two first metal tracks PM11 and PM12 in the crossing region RC of said at least one first module MOD1.

(46) Advantageously, the use of this adjustment capacitor CA allows an overall capacitive value to be obtained without much of an increase in the size of said coupling stage EC.

(47) The coupling stage EC has an overall inductive value, an overall capacitive value, dimensional constraints measured along the two stage axes of symmetry ASE1 and ASE2.

(48) The type of module MOD1 and/or MOD2, the number and the size of the modules, and of the connection tracks and of the adjustment capacitors CA forming said coupling stage EC are chosen so as to comply with said overall inductive value, said overall capacitive value and said dimensional constraints.

(49) Reference will now more particularly be made to FIGS. 10 to 12 in order to illustrate another example of design of a coupling stage EC.

(50) It is assumed in this example that it is desired to form a coupling stage EC having an overall capacitive value equal to 135 fF and an overall inductive value equal to 685 pH. The distance between components, here for example power amplifiers AP, coupled to said coupling stage is for example 220 μm. The rms value of the current in the coupling stage is limited for example to 100 mA so that a minimum width for all of the metal tracks of said coupling stage EC may be determined.

(51) As indicated hereinbefore, the effective overall capacitive value and the effective overall inductive value of said coupling stage EC are mainly determined by said first module MOD1 and said second module MOD2 of said coupling stage EC.

(52) Consequently, said coupling stage EC illustrated in FIG. 10 comprises five branches B1_10 to B5_10 each having a group G having a first module MOD1 coupled in series between two second modules MOD2.

(53) Each first module MOD1 of said group G has a capacitive value of 12.9 fF and an inductive value of 8 pH, whereas each second module MOD2 of said group G has a capacitive value of 17.8 fF and an inductive value of 67 pH.

(54) In that case, if the inductive value of the first module MOD1 is ignored, each branch of said coupling stage EC has a capacitive value of around 49 fF and an inductive value of 134 pH.

(55) In order to reach the overall inductive value of 685 pH, it is chosen to form five branches coupled via metal connection tracks PMR1 and PMR2 which are used to obtain the remainder of the overall inductive value, i.e. 15 pH. The effective overall capacitive value of the five branches is equal to 245 fF, which is close to twice the overall inductive value, i.e. 268 fF. As a consequence, an adjustment capacitor CA coupled to one of the first modules MOD1 of said coupling stage EC and having a capacitive value of 23 fF just needs to be provided.

(56) A finer adjustment to the overall capacitive and inductive values could potentially be applied in such a manner as to adjust the central frequency of said 90° hybrid coupling stage.

(57) FIG. 11 illustrates schematically a wireless communications device APP, for example a cellular mobile telephone, comprising a transmission chain CT containing a first coupling stage EC1 described hereinbefore being used as a power divider DIV, a second coupling stage EC2 being used as a power combiner COMB, and two power amplifiers AP1 and AP2 respectively coupled between the first coupling stage EC1 and the second coupling stage EC2.

(58) One of the two first stage terminals BE11_1 of said first coupling stage EC1 receives a first input signal SE1, for example a radiofrequency signal coming from a frequency transformation stage, and the other of the two first stage terminals BE12_1 is coupled to a load CHG50 having a characteristic impedance of 50 ohms and being connected to ground so as to be isolated. The two second stage terminals BE21_1 and BE22_1 of said first coupling stage EC1 each deliver a first output signal SS1 and these first output signals SS1 are phase-shifted by 90° with respect to each other.

(59) Thanks to the topology of the first and second coupling stages EC1 and EC2, the two power amplifiers AP1 and AP2 are coupled in parallel between the two second stage terminals BE21_1 and BE22_1 of said first coupling stage EC1 and the two second stage terminals BE21_2 and BE22_2 of said second coupling stage EC2, which advantageously allows the size of said device APP to be reduced.

(60) Said second coupling stage EC2 receives, at its two second stage terminals BE21_2 and BE22_2, the intermediate output signals SSI coming from the two power amplifiers AP1 and AP2 and delivers to one of the two first stage terminals BE11_2 a second output signal SS2, for example an amplified radiofrequency signal intended to be transmitted via an antenna for example. The other of the two first stage terminals BE12_2 of said second coupling stage EC2 is coupled to a load CHG50 having a characteristic impedance of 50 ohms and being connected to ground so as to be isolated.

(61) As a variant, FIG. 12 illustrates schematically an example of a third coupling stage EC3 used in a phase-shift device DD, incorporated for example into an apparatus APP1 such as for example a radio frequency phase-shifter.

(62) More precisely, one of the two second stage terminals BE21 of said third coupling stage EC3 receives a third input signal SE3 and the other of the two second stage terminals BE22 delivers a third output signal SS3. The two first stage terminals BE11 and BE12 are respectively coupled to first and second variable loads CV1 and CV2 having variable impedances and being respectively connected to ground.

(63) The phase shift between said third input signal SE3 and said third output signal SS3 is adjustable by modifying the impedances of said first and second variable loads CV1 and CV2.

(64) Thus, a coupling device is obtained comprising a coupling stage of limited size able to be used for example as a divider, combiner or else phase-shift device, and allowing a fast and easy adjustment of the dimensions and the capacitive and inductive values of said coupling stage.

(65) Furthermore, the fact that the input terminals of said stage in combiner mode and the output terminals of said stage in divider mode are situated in the same side of said coupling stage advantageously allows a parallel coupling of the components such as power amplifiers with a reduced space requirement.

(66) The invention is not limited to the embodiments that have just been described but encompasses all their variants.

(67) Thus, although coupling stages within coupling devices disposed on a substrate of the silicon type, with a dielectric between the tracks, have been described, these coupling stages may also be implemented on a printed circuit, within a packaging module or else in the air in suspended mode.