Quadrature coupler

Abstract

A quadrature coupler having: a pair of overlying strip conductors separated by a first dielectric layer to provide a coupling region between the coupling region of overlying strip conductors; a pair of opposing ground pads, the coupling region being disposed between the pair of opposing ground pads; a second dielectric layer disposed over the coupling region and between the pair of opposing ground pads; and an electrically conductive shield layer disposed over the second dielectric layer, extending over opposing sides of the dielectric layer and onto the pair of opposing ground pads. Portions of coupler are formed by printing or additive manufacturing.

Claims

1. A radio frequency coupler, comprising: a dielectric substrate; a pair of strip conductors disposed over an upper surface of the dielectric substrate, a first portion of the pair of strip conductors being in an overlying relationship and separated by a first dielectric layer to provide a coupling region between the portion of the pair of strip conductors in the overlying relationship; a second portion of the pair of strip conductors being disposed on the upper surface of substrate; a pair of opposing ground pads disposed on, and separated by, different portions of the upper surface of the substrate, the coupling region being disposed between the pair of opposing ground pads; a second dielectric layer disposed over the coupling region and between the pair of opposing ground pads; an electrically conductive shield layer disposed over the second dielectric layer, extending over opposing sides of the second dielectric layer and onto the pair of opposing ground pads.

2. The radio frequency coupler recited in claim 1 including a second pair of ground pads disposed on, and separated by, different portions the upper surface of the substrate, the coupling region being disposed between the second pair of ground pads, the first-mentioned pair of ground pads, the first-mentioned pair of ground pads and the second pair of ground pads being disposed along perpendicular lines, the electrically conductive shield layer being disposed over a second pair of opposing sides of the dielectric layer and onto the second pair of ground pads.

3. The radio frequency coupler recited in claim 2 wherein one of the second portion of the pair of strip conductors pass between one of the first mentioned pair of ground pads and one of the second pair of ground pads.

4. The radio frequency coupler recited in claim 3 wherein a second one of the second portion of the pair of strip conductors pass between a second one of the first mentioned ground pads and a second one of the second pair of ground pads.

5. The radio frequency coupler recited in claim 1 wherein the electrically conductive shield layer is a conductive ink.

6. The radio frequency coupler recited in claim 1 wherein portions of the electrically conductive shield layer are disposed on sides of the first dielectrics layer and sides of the second dielectric layer and over on portions of the upper surface of the dielectric substrate.

7. The radio frequency coupler recited in claim 6 including a second pair of ground pads disposed on, and separated by, different portions the upper surface of the substrate, the coupling region being disposed between the second pair of ground pads, the first-mentioned pair of ground pads, the first-mentioned pair of ground pads and the second pair of ground pads being disposed along perpendicular lines, the electrically conductive shield layer being disposed over a second pair of opposing sides of the dielectric layer and onto the second pair of opposing ground pads.

8. The radio frequency coupler recited in claim 7 wherein a first one of the second portion of the pair of strip conductors pass between one of the first mentioned pair of ground pads and one of the second pair of ground pads.

9. The radio frequency coupler recited in claim 8 wherein a second one of the second portion of the pair of strip conductors pass between a second one of the first mentioned ground pads and a second one of the second pair of ground pads.

10. The radio frequency coupler recited in claim 8 wherein the electrically conductive shield layer is a conductive ink.

11. The radio frequency coupler recited in claim 9 wherein the electrically conductive shield layer is a conductive ink.

12. A radio frequency coupler, comprising: a dielectric substrate; a first metal layer disposed on an upper surface of the substrate, the first metal layer being patterned to provide: a pair of ground pads disposed on, and separated by, different portions of the dielectric substrate; a first lower strip conductor, spaced from the pair of ground pads, having: an input at first end, an output at a second end; and, a coupling region disposed between the first end, the second end, and between the pair of ground pads; a second lower strip conductor having: an input end and an output end; and, a third lower strip conductor having an input end and an output end; a first dielectric layer disposed over the coupling region; a second metal layer configured as a strip conductor disposed on the first dielectric layer over the coupling region, the second metal layer having one end disposed on, and electrically connected to, the output end of the second lower strip conductor and having a second end disposed on, and electrically connected to the input end of the third lower strip conductor; and a second dielectric layer is disposed over the second metal layer and between the pair of ground pads; and an electrically conductive shield layer disposed on an upper surface of the second dielectric layer extending over sides of the second dielectric layer and onto the pair of ground pads.

13. The radio frequency coupler recited in claim 12 wherein the first metal layer is patterned to provide a second pair of ground pads on, and separated by, different portions of the upper surface of the dielectric substrate the coupling region being disposed between the second pair of ground pads, the first-mentioned pair of ground pads, the first-mentioned pair of ground pads and the second pair of ground pads being disposed along perpendicular lines, the electrically conductive shield layer being disposed over a second pair of opposing sides of the dielectric layer and onto the second pair of ground pads.

14. The radio frequency coupler recited in claim 13 wherein one of the first lower strip conductors pass between one of the first mentioned pair of ground pads and one of the second pair of ground pads.

15. The radio frequency coupler recited in claim 14 wherein a second one of the second lower strip conductors pass between a second one of the first mentioned and a second one of the second pair of ground pads.

16. The radio frequency coupler recited in claim 12 wherein the electrically conductive shield layer is a conductive ink.

17. The radio frequency coupler recited in claim 12 wherein the portions of the electrically conductive shield layer are disposed on sides of the first dielectrics layer and sides of the second dielectric layer and over portions of the upper surface of the dielectric substrate.

18. A method for tuning a radio frequency coupler, comprising: (a) providing a radio frequency coupler comprising: a dielectric substrate; a pair of strip conductors disposed over an upper surface of the dielectric substrate, a first portion of the pair of strip conductors being in an overlying relationship and separated by a first dielectric layer to provide a coupling region between the portion of the pair of strip conductors in the overlying relationship; a second portion of the pair of strip conductors being disposed on the upper surface of substrate; and a pair of opposing ground pads disposed on the upper surface of the substrate, the coupling region being disposed between the pair of opposing ground pads; (b) measuring a degree coupling between the pair of strip conductors; (c) comparing the measured degree of coupling with a predetermined degree of coupling; (d) adjusting a width of an upper one of the pair of strip conductors widths; (e) repeating (b) through (d) until the degree of coupling reaches the predetermined degree coupling-.

Description

DESCRIPTION OF DRAWINGS

(1) FIGS. 1A-1C through 5A-5C are diagrammatical plan, perspective, and cross sectional views of a quadrature coupler according to the disclosure at various stages in the fabrication thereof;

(2) FIGS. 1B and 1C being taken along lines 1B-1B and 1C-1C, respectively in FIG. 1A;

(3) FIGS. 2B and 2C being taken along lines 2B-2B and 2C-2C, respectively in FIG. 2A;

(4) FIGS. 3B and 3C being taken along lines 3B-3B and 3C-3C, respectively in FIG. 3A;

(5) FIG. 3D being a perspective view of a region indicated as 3D-3D in FIG. 2A;

(6) FIGS. 4B and 4C being taken along lines 4B-4B and 4C-4C, respectively in FIG. 4A;

(7) FIGS. 5B and 5C being taken along lines 5B-5B and 5C-5C, respectively in FIG. 5A; and

(8) FIGS. 6A and 6B are flow charts of steps used in the process used to fabricate the quadrature coupler of FIGS. 5A-5C.

(9) Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

(10) Referring now to FIGS. 1A, 1B and 1C, a dielectric substrate 12 is shown having: a first metal layer 14 disposed on an upper surface of the substrate 12; and a ground plane conductor 13, here for example gold, is disposed on a bottom surface of the substrate 12. The first metal layer 14 is patterned to provide: a two pairs of ground pads; pair 16a.sub.1, 16a.sub.2, and pair 16b.sub.1, 16b.sub.2, respectively, as shown; a first lower strip conductor 18, spaced from the pair of ground pads, having: an input at first end 18.sub.I, an output at a second end 18.sub.O; and, a coupling region 20 disposed between the first end 18.sub.I, the second end 18.sub.O, and between the two pairs on ground pads 16a.sub.1, 16a.sub.2, and pair 16b.sub.1, 16b.sub.2, respectively, as shown; a second lower strip conductor 22 having: an input end 22.sub.I and an output end 22.sub.O; and, a third lower strip conductor 24 having an input end 24.sub.I and an output end 24.sub.O, as shown. The first metal layer 14 may be printed, formed using additive manufacturing, or formed using conventional photolithographic-etching processing, as used in forming printed circuit boards, for example.

(11) Referring now to FIGS. 2A-2C, a first dielectric layer 26, here for example epoxy based dielectric ink 118-12 from Creative Materials, Ayer, Mass. is disposed over the coupling region 20 using printing or additive manufacturing, for example.

(12) Referring now to FIGS. 3A-3D, a second metal layer, strip conductor 28 here printed or formed by additive manufacturing, for example, using a conductive ink, for example, Paru nanosilver PG-007 or Dupont CB028, as a strip conductor disposed on the first dielectric layer 20. It is noted that portions 28a and 28b of the second metal layer are formed over portions of the outer sidewalls of the first dielectric layer 26 onto portions of the output end 24.sub.o of the lower strip conductor 24 and onto portions of the input end 22.sub.I of the third lower strip conductor 22. Thus, second metal layer 28 has one end 28a disposed on, and electrically connected to, the input end 22, of the second lower strip conductor 22 and has a second end 28b disposed on, and electrically connected to the output end 24.sub.O of the third lower strip conductor 24. The width of the second metal layer 28 over the coupling region 20 may be adjusted by the additive manufacturing or printing process to tune the quadrature coupler 10.

(13) Referring now to FIGS. 4A-4C, a second dielectric layer 30 is disposed over the second metal layer 28 and between the two pairs of ground pads 16a.sub.1, 16a, and pair 16b.sub.1, 16b.sub.2, as shown. The second dielectric layer 30 may be printed or formed by additive manufacturing, for example, using any suitable dielectric, for example epoxy based dielectric ink 118-12 from Creative Materials, Ayer, Mass.

(14) Referring now to FIGS. 5A-5C, an electrically conductive shield layer 32 is disposed on an upper surface of the second dielectric layer 30 extending over sides of the second dielectric layer 30 and onto the pair of ground pads 16a.sub.1, 16a.sub.2, and pair 16b.sub.1, 16b.sub.2, as shown. Conductive layers 34a, 34b are disposed on the sides of the substrate 12 to electrically connect the ground pads 16a.sub.1, 16a.sub.2 to the ground plane conductor 13, as shown, thereby completing the quadrature coupler 10. It is noted that the conductive shield layer 32 and conductive layers 34a, 34b are here printed or formed by additive manufacturing, for example, using a conductive ink, for example Para nanosilver PG-007 or DuPont CB028.

(15) Because of the additive manufacturing printing process, the quadrature coupler 10 can be easily tuned. More particularly, referring to FIGS. 6A and 6B, first, prior to the manufacturing process a determination is made as to the width required for the strip conductor 28 prior to forming the dielectric material 30 (FIGS. 5A-5C) so that the competed quadrature coupler 10 will have a proper width to produce quadrature coupler 10 with a desired, predetermined degree of coupling between the upper strip conductor 28 and the lower strip conductor 20 after forming the dielectric material 30 and shield 34. Thus, referring to FIG. 6A, a computer simulation, using, for example 3-dimensional electro-magnetic simulator such as Ansys-HFFS (Ansys corporation, Canonsburg, Pa. 15317) is used to model a completed quadrature coupler 10 comprising: entering parameters of the simulated completed quadrature coupler, such parameters including: a width for upper strip conductor 28 estimated to provide a predetermined, desired degree of coupling between the lower strip conductor 20 and the upper strip conductor 28; the dielectric materiel 26, its thickness and its dielectric constant; the dielectric materiel 30, its thickness and its dielectric constant; and shield layer 32 into a computer simulator to have the computer generate the actual degree of coupling produced by the simulated quadrature coupler. From the generated actual degree of coupling, a comparison is made between the generated actual degree of coupling and a predetermined desired degree of coupling. If the generated actual degree of coupling and the predetermined desired degree of coupling are different, the width of the upper strip conductor 28 in the simulation is changed and the process continues until they are equal. Next, the dielectric material 26, its thickness and its dielectric constant; and shield layer 32 are removed from the simulation to thereby provide a computer model of the coupler at an intermediate stage in its fabrication, shown in FIGS. 3A-3C. Next, the degree of coupling of such coupler at the intermediate stage in its fabrication is recorded.

(16) This recorded degree of coupling is used during the actual fabrication of the quadrature coupler 10. More particularly, referring to FIG. 6B, the fabrication process includes: (a) providing the quadrature coupler after completion of the structure shown in FIGS. 3A-3C with the width of the upper strip conductor 28 having a minimum predicted width; (b) measuring the degree coupling between the pair of strip conductors using any conventional process such as for example an S-parameter analyzer; (c) comparing the measured degree of coupling with the recorded degree of coupling; (d) incrementally increasing the width of the upper strip conductor 28 (FIGS. 3A-3C); (e) repeating (b) through (d) until the degree of coupling reaches the recorded degree coupling; and (f) complete the quadrature coupler 10 as described above and in connection with FIGS. 4A-4C through 5A-5C. It should be understood that instead of setting a minimum coupler specification and line width 28 and increasing line width 28 to achieve the desired coupler, a nominal or larger line width for 28 for the coupler can be used and techniques such as laser trim or milling tools can be used to reduce the line width to the desired level.

(17) A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, instead of Conductive layers 34a, 34b disposed on the sides of the substrate 12 to electrically connect the ground pads 16a.sub.1, 16a.sub.2 to the ground plane conductor 13, the ground pads 16a.sub.1, 16a.sub.2, and pair 16b.sub.1, 16b.sub.2, may be connected to the ground plane conductor 13 with electrically conductive vias passing through the substrate 12. These vias may be formed prior to forming the first metal layer 14 (FIGS. 1A-1C). Accordingly, other embodiments are within the scope of the following claims.