Substrate design for efficient coupling between a package and a dielectric waveguide
A device includes a multilayer substrate having a first surface and a second surface opposite the first surface. An integrated circuit is mounted on the second surface of the multilayer substrate, the integrated circuit having transmission circuitry configured to process millimeter wave signals. A substrate waveguide having a substantially solid wall is formed within a portion of the multilayer substrate perpendicular to the first surface. The substrate waveguide has a first end with the wall having an edge exposed on the first surface of the multilayer substrate. A reflector is located in one of the layers of the substrate and is coupled to an edge of the wall on an opposite end of the substrate waveguide.
1. An integrated substrate comprising:
a first body of insulating material having a first side and a second side, the sides being opposite one another;
a first conductive layer on the first side;
conductive waveguide tops arranged in a geometric pattern on the second side;
a waveguide formed in the substrate between the first conductive layer and the waveguide tops, the waveguide including conductive waveguide vias connecting the first conductive layer to the waveguide tops, the waveguide vias being arranged in the geometric pattern through the body of insulating material to form a substantially solid waveguide wall having the geometric pattern;
antennas formed in a metal layer on the second side of the substrate, the antennas being within the geometric pattern of the waveguide tops;
a second body of insulating material having a third side formed on the first conductive layer opposite the first body and having a fourth side opposite the third side;
antenna pads formed on the fourth side of the second body; and
antenna vias formed in the first body and in the second body connecting the antennas to the antenna pads.
2. The integrated substrate of claim 1 in which the waveguide vias have diameters and the substantially solid waveguide wall is formed by the distances between adjacent waveguide vias being less than the diameters.
3. The integrated substrate of claim 1 in which the substantially solid waveguide wall is formed by distances between adjacent waveguide vias being less than a wave length of a millimeter signal adapted to be carried by the waveguide.
4. The integrated substrate of claim 1 in which the waveguide vias have diameters and the substantially solid waveguide wall is formed by adjacent waveguide vias touching one another.
5. The integrated substrate of claim 1 in which the geometric pattern is circular.
6. The integrated substrate of claim 1 in which the waveguide vias are arranged to be tapered from the first conductive layer radially outward to the waveguide tops.
7. The integrated substrate of claim 1 including groups of waveguide vias connecting the first conductive layer to the waveguide tops, each group connecting the first conductive layer to one waveguide top and each group including waveguide pads connecting together the waveguide vias of that group.
8. The integrated substrate of claim 1 in which the waveguide tops are metal pads in a metal layer on the second side of the substrate.
9. The integrated substrate of claim 1 in which the waveguide tops are equally spaced on the second side of the substrate.
10. The integrated substrate of claim 1 in which the conductive first layer includes openings for the antenna vias.
11. The integrated substrate of claim 1 in which the antennas are generally rectangular members, with a rounded end, and are physically positioned and aligned 90 degrees apart from each other.
12. The integrated substrate of claim 1 in which a distance from the waveguide tops to the first layer is approximately λ/4 of a transmission signal though the waveguide.
13. The integrated substrate of claim 1 in which the waveguide tops are arranged in one row.
14. The integrated substrate of claim 1 in which the waveguide tops are arranged in two rows.
15. The integrated substrate of claim 1 in which the waveguide tops are arranged in two circular rings.
16. A system comprising:
(a) an integrated substrate including:
a first body of insulating material having a first side and a second side, the sides being opposite one another;
a first conductive layer on the first side;
conductive waveguide tops arranged in a geometric pattern on the second side; and
a waveguide formed in the substrate between the first conductive layer and the waveguide tops, the waveguide including conductive waveguide vias connecting the first conductive layer to the waveguide tops, the waveguide vias being arranged in the geometric pattern through the body of insulating material to form a substantially solid waveguide wall having the geometric pattern;
antennas formed in a metal layer on the second side of the substrate, the antennas being within the geometric pattern of the waveguide tops;
a second body of insulating material having a third side formed on the first conductive layer opposite the first body and having a fourth side opposite the third side;
antenna pads formed on the fourth side of the second body; and
antenna vias formed in the first body and in the second body connecting the antennas to the antenna pads;
(b) an integrated circuit coupled to the antenna pads; and
(c) an interposer having a conductive lower edge coupled to the waveguide tops.
17. The integrated substrate of claim 16 in which the waveguide vias have diameters and the substantially solid waveguide wall is formed by the distances between adjacent waveguide vias being less than the diameters.
18. The integrated substrate of claim 16 in which the substantially solid waveguide wall is formed by distances between adjacent waveguide vias being less than a wave length of a millimeter signal adapted to be carried by the waveguide.
19. The integrated substrate of claim 16 in which the waveguide vias have diameters and the substantially solid waveguide wall is formed by adjacent waveguide vias touching one another.
20. The integrated substrate of claim 16 in which the geometric pattern is circular.
21. The integrated substrate of claim 16 in which the waveguide vias are arranged to be tapered from the first conductive layer radially outward to the waveguide tops.
22. The integrated substrate of claim 16 including groups of waveguide vias connecting the first conductive layer to the waveguide tops, each group connecting the first conductive layer to one waveguide top and each group including waveguide pads connecting together the waveguide vias of that group.
23. The integrated substrate of claim 16 in which the waveguide tops are metal pads in a metal layer on the second side of the substrate.
24. The integrated substrate of claim 16 in which the waveguide tops are equally spaced on the second side of the substrate.
25. The integrated substrate of claim 16 in which the conductive first layer includes openings for the antenna vias.
26. The integrated substrate of claim 16 in which the antennas are generally rectangular members, with a rounded end, and are physically positioned and aligned 90 degrees apart from each other.
27. The integrated substrate of claim 16 in which a distance from the waveguide tops to the first layer is approximately λ/4 of a transmission signal though the waveguide.
28. The integrated substrate of claim 16 in which the waveguide tops are arranged in one row.
29. The integrated substrate of claim 16 in which the waveguide tops are arranged in two rows.