Vertical inter-digital coupler
View Patent ↗The present invention is directed to a coupler structure that includes a first port, a second port, a third port, and a fourth port. L first transmission line layers are disposed in the structure. Each first transmission line layer includes a first transmission line conforming to a predetermined geometric configuration. The first transmission line is disposed on a first dielectric material between the first port and the second port. L is an integer. M second transmission line layers are disposed in alternating layers with the L first transmission line layers to form a total of N transmission line layers within the structure. M and N are integers and N is greater than or equal to three. Each second transmission line layer includes a second transmission line substantially conforming to the predetermined geometric configuration. The second transmission line is disposed on a second dielectric material between the third port and the fourth port. Each second transmission line is disposed in a predetermined position relative to a corresponding first transmission line within the structure.
1. A coupler structure comprising:
a first port, a second port, a third port, and a fourth port accessible via an exterior of the coupler structure;
L first transmission line layers disposed in the coupler structure, each first transmission line layer including a first transmission line conforming to a predetermined geometric configuration, the first transmission line being disposed on a first dielectric material between the first port and the second port, L being an integer; and
M second transmission line layers disposed in alternating layers with the L first transmission line layers to form a total of N transmission line layers, M and N being integers with N being greater than or equal to three, each second transmission line layer including a second transmission line substantially conforming to the predetermined geometric configuration, the second transmission line being disposed on a second dielectric material between the third port and the fourth port, each second transmission line being disposed in a predetermined position relative to a corresponding first transmission line within the structure, the coupler structure being characterized by a volume, the volume being a function of N and the predetermined geometric configuration for a selected coupling constant, the volume being inversely proportional to N over a first range of values for N.
2. The coupler structure of claim 1 , wherein the predetermined volume is a non-linear function of N.
3. The coupler structure of claim 1 , wherein the volume includes a cross-sectional area, the cross-sectional area being a function of N such that the cross-sectional area being inversely proportional to the value of N over a second range of values for N, and wherein the predetermined geometric configuration corresponds to a geometric transmission line pattern and a linewidth of the first transmission line and the second transmission line.
4. The coupler structure of claim 3 , wherein the cross-sectional area is is substantially equal to:
A N =( s+w )[2 h +( N− 1) d+Ntm ]; and
wherein s is a horizontal spacing between adjacent conductors of a first transmission line or a second transmission line, w is a horizontal width of each said conductor, h is a vertical distance from an outermost conductor of the first transmission line or the second transmission line, d is a vertical distance between a first transmission line conductor and a second transmission line conductor, t is a vertical height of each first transmission line conductor and each second transmission line conductor, and m is a ratio in a horizontal direction of conducting material to dielectric material.
5. The coupler structure of claim 1 , wherein the predetermined geometric configuration is substantially linear.
6. The coupler structure of claim 1 , wherein the predetermined geometric configuration includes at least one substantially rectangular geometric pattern.
7. The coupler structure of claim 1 , wherein the predetermined geometric configuration is a non-linear geometric configuration.
8. The coupler structure of claim 1 , wherein the predetermined geometric configuration includes at least one meandered line segment.
9. The coupler structure of claim 1 , wherein the predetermined geometric configuration includes a spiral configuration.
10. The coupler structure of claim 1 , wherein the coupler structure is characterized by a finite even-mode impedance and a finite odd-mode impedance.
11. The coupler structure of claim 10 , wherein a ratio of the finite even-mode impedance to the finite odd-mode impedance is substantially within a range between 1:1 to 1:10.
12. The coupler structure of claim 1 , wherein the length of each of the first transmission lines and/or each of the second transmission lines is substantially equal to λ/4.
13. The coupler structure of claim 1 , wherein the first transmission lines and the second transmission lines are comprised of a metallic material.
14. The coupler structure of claim 13 , wherein the metallic material includes copper.
15. The coupler structure of claim 1 , wherein the first dielectric material and/or the second dielectric material is selected from a group of materials that includes a polymer material, a thermoplastic material, a ceramic material, a thermoset material, polytetrfluoroethylene, or a curable resin material.
16. The coupler structure of claim 1 , wherein the alternating layers of L transmission line layers and M transmission line layers are disposed between a pair of ground plates.
17. The coupler structure of claim 1 , wherein N is greater than or equal to twenty.
18. The coupler structure of claim 1 , wherein the selected coupling constant is approximately equal to zero (0) dB.
19. The coupler structure of claim 1 , wherein the selected coupling constant is less than or equal to 3 dB.
20. The coupler structure of claim 1 , wherein the selected coupling constant is greater than 3 dB.
21. The coupler structure of claim 1 , wherein each second transmission line is disposed in substantial vertical alignment with the corresponding first transmission line within the structure.
22. A coupler structure having a form factor characterized by predetermined dimensional specifications, the predetermined dimensional specifications including a cross-sectional area, the coupler structure comprising:
a first port, a second port, a third port, and a fourth port accessible via an exterior of the coupler structure;
L-first transmission line layers disposed in the structure, L being an integer value, each first transmission line layer including a first transmission line conforming to a predetermined geometric configuration, the first transmission line being disposed on a first substrate and coupled between the first port and the second port; and
M-second transmission line layers disposed in alternating layers with the L-first transmission line layers to form a total of N transmission line layers, M and N being integers and N being greater than or equal to three, each second transmission line layer including a second transmission line substantially conforming to the predetermined geometric configuration, the second transmission line being disposed on a second substrate and coupled between the third port and the fourth port, each second transmission line being disposed in a predetermined position relative to a corresponding first transmission line within the structure, the predetermined dimensional specifications and the cross sectional area being a function of N and the predetermined geometrical configuration for a selected coupling constant, the cross-sectional area being inversely proportional to N over a range of values for N.
23. The coupler structure of claim 22 , wherein the cross-sectional area is a non-linear function of N.
24. The coupler structure of claim 22 , wherein the cross-sectional area is substantially equal to:
A N =( s+w )[2 h =( N− 1) d+Ntm ]; and
wherein s is a horizontal spacing between adjacent conductors of a first transmission line or a second transmission line, w is a horizontal width of each said conductors, h is a vertical distance from an outermost conductor of the first transmission line or the second transmission line, d is a vertical distance between a first transmission line conductor and a second transmission line conductor, t is a vertical height of each first transmission line conductor and each second transmission line conductor, and m is a ratio in a horizontal direction of conducting material to dielectric material.
25. The coupler structure of claim 22 , wherein the coupler structure is characterized by a finite even-mode impedance and a finite odd-mode impedance.
26. The coupler structure of claim 25 , wherein a ratio of the finite even-mode impedance to the finite odd-mode impedance is substantially within a range between 1:1 to 1:100.
27. The coupler structure of claim 22 , wherein the length of each of the first transmission lines and/or each of the second transmission lines is substantially equal to λ/4.
28. The coupler structure of claim 22 , wherein the alternating layers of L transmission line layers and M transmission line layers are disposed between a pair of ground plates.
29. The coupler structure of claim 22 , wherein N is greater than or equal to twenty.
30. The coupler structure of claim 22 , wherein the selected coupling constant is approximately equal to zero (0) dB.
31. The coupler structure of claim 22 , wherein the selected coupling constant is less than or equal to 3 dB.
32. The coupler structure of claim 22 , wherein the selected coupling constant is greater than 3 dB.
33. The coupler structure of claim 22 , wherein each second transmission line is disposed in substantial vertical alignment with the corresponding first transmission line within the structure.
34. A method for making a coupler structure having a predetermined volume that includes, a predetermined cross-sectional area, the method comprising:
(a) selecting a coupling constant;
(b) determining a geometrical configuration and a value N in accordance with the predetermined volume and the selected coupling constant, N being an integer value greater than or equal to three (3) corresponding to N alternating layers of L first transmission lines and M second transmission lines, L and M also being integers, the predetermined volume being a function of N and the geometric configuration for the selected coupling constant, the predetermined volume being inversely proportional to N over a first range of values for N;
(c) providing a first transmission line layer, the first transmission line layer including a first transmission line disposed on a first dielectric material and conforming to a predetermined geometric configuration;
(d) disposing a second transmission line layer on the first transmission line layer, second transmission line layer including a second transmission line being vertically aligned to the first transmission line and substantially conforming to the predetermined geometric configuration, the second transmission line being disposed on a second dielectric material;
(e) bonding the first transmission line layer and the second transmission line layer;
(f) repeating steps (a)-(e) to form a laminate structure comprising the N alternating layers of the L first transmission line layers and the M second transmission line layers;
(g) coupling a first end of the L first transmission lines to a first port and a second end of the L first transmission lines to a second port; and
(h) coupling a first end of the M second transmission lines to a third port and a second end of the M second transmission lines to a fourth port.
35. The method of claim 34 wherein the predetermined volume is a non-linear function of N.
36. The method of claim 34 , wherein the step of providing the first transmission line layer further comprises:
providing a conductive sheet bonded to the first dielectric material;
disposing a pattern in accordance with the predetermined geometric configuration on the conductive sheet; and
etching the conductive sheet to remove excess conductive material.
37. The method of claim 36 , wherein the step of disposing a pattern in accordance with the predetermined geometric shape on the conductive sheet is performed using at least one photolithographic technique.
38. The method of claim 34 , wherein the step of bonding is performed by applying heat and/or pressure to the first transmission line layer and the second transmission line layer.
39. The method of claim 36 , wherein the conductive sheet is comprised of a metallic material.
40. The method of claim 39 , wherein the metallic material is a copper material.
41. The method of claim 34 , wherein the first dielectric material and/or the second dielectric material is selected from a group of materials that includes a polymer material, a thermoplastic material, a ceramic material, a thermoset material, polytetrafluoroethylene, or a curable resin material.
42. The method of claim 34 , wherein the alternating layers of L transmission line layers and M transmission line layers are disposed between a pair of ground plates.
43. The method of claim 34 wherein the cross-sectional area is substantially equal to:
A N =( s+w )[2 h +( N− 1) d+Ntm ]; and
wherein s is a horizontal spacing between adjacent conductors of a first transmission line or a second transmission line, w is a horizontal width of each of said conductors, h is a vertical distance from an outermost conductor of the first transmission line or the second transmission line, d is a vertical distance between a first transmission line conductor and a second transmission line conductor, t is a vertical height of each first transmission line conductor and each second transmission line conductor, and m is a ratio in a horizontal direction of conducting material to dielectric material.
44. The method of claim 34 , wherein the length of each of the first transmission lines and/or each of the second transmission lines is substantially equal to λ/4.