Embedded filtering in PCB integrated ultra high speed dielectric waveguides using photonic band gap structures

Patent metadata

Field	Value
Publication number	US-10879575-B2
Application number	US-201816151856-A
Country	US
Kind code	B2
Filing date	Oct 4, 2018
Priority date	Oct 4, 2018
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

A method and apparatus for attenuating crosstalk between dielectric waveguides is provided. A first dielectric waveguide is formed to carry a first frequency band. A first filter is embedded within the first dielectric waveguide to attenuate transmission of a second frequency band through the first dielectric waveguide. The filter comprises alternating sections of a first dielectric material and a second dielectric material having different dielectric constants. The length of each section of the first and second dielectric materials is equal to a quarter of the wavelength of the central frequency of the second frequency band. A second waveguide is formed to carry the second frequency band. A second filter is embedded in the second dielectric waveguide to attenuate transmission of the first frequency band through the second dielectric waveguide. A cladding is disposed between the first and second waveguides.

First claim

The invention claimed is:

1. A dielectric waveguide layer, comprising:
a first dielectric core forming a first waveguide;
a cladding disposed on opposite sides of the dielectric core, wherein the cladding has a lower dielectric constant than the first dielectric core;
a first filter embedded within the first dielectric core and configured to attenuate transmission of a first frequency band through the first waveguide, wherein the first filter comprises alternating sections of a first dielectric material and a second dielectric material having different dielectric constants, and wherein a length of each section of the first and second dielectric materials within the first filter is equal to a quarter of a wavelength of a central frequency of the first frequency band; and
a first conductive ground plane in contact with top surfaces of the first dielectric core, the second dielectric core, and the cladding; and
a second conductive ground plane in contact with bottom surfaces of the first dielectric core, the second dielectric core, and the cladding.

2. The waveguide layer of claim 1 , wherein the first dielectric material in the first filter has a dielectric constant equal to the dielectric constant of the first dielectric core.

3. The waveguide layer of claim 1 , wherein the second dielectric material in the first filter has a dielectric constant equal to the dielectric constant of the cladding.

4. The waveguide layer of claim 1 , wherein the second dielectric material in the first filter has a dielectric constant higher than the dielectric constant of the cladding.

5. The waveguide layer of claim 1 , wherein the first filter has a Q factor that is directly proportional to a number of transitions between the first and second dielectric materials.

6. The waveguide layer of claim 1 , further comprising a second filter embedded in the first dielectric core and configured to attenuate transmission of a second frequency band through the first waveguide, wherein the second filter comprises alternating sections of the first dielectric material and the second dielectric material, and wherein a length of each section of the first and second dielectric materials within the second filter is equal to a quarter of a wavelength of a central frequency of the second frequency band.

7. The waveguide layer of claim 1 , further comprising:
a second dielectric core forming a second waveguide separated from the first waveguide by the cladding; and
a second filter embedded in the second dielectric core and configured to attenuate transmission of a second frequency band through the second waveguide, wherein the second filter comprises alternating sections of the first dielectric material and the second dielectric material, and wherein a length of each section of the first and second dielectric materials within the second filter is equal to a quarter of a wavelength of a central frequency of the second frequency band;
wherein the second frequency band equals a third frequency band transmitted through the first waveguide, and wherein the first frequency band equals a fourth frequency band transmitted through the second waveguide.

8. A multi-layer printed circuit board (PCB), comprising:
a first dielectric core forming a first waveguide configured to transmit a first frequency band;
a first filter embedded within the first dielectric core and configured to attenuate transmission of a second frequency band through the first waveguide, wherein the first filter comprises alternating sections of a first dielectric material and a second dielectric having different dielectric constants, and wherein a length of each section of the first and second dielectric materials within the first filter is equal to a quarter of a wavelength of a central frequency of the second frequency band;
a second dielectric core forming a second waveguide configured to transmit the second frequency band;
a second filter embedded in the second dielectric core and configured to attenuate transmission of the first frequency band through the second waveguide, wherein the second filter comprises alternating sections of the first dielectric material and the second dielectric material, and wherein a length of each section of the first and second dielectric materials within the second filter is equal to a quarter of a wavelength of a central frequency of the first frequency band;
a cladding disposed between the first dielectric core and second dielectric core, wherein the cladding has a lower dielectric constant than a dielectric constant of the first and second dielectric cores;
a first conductive ground layer in contact with top surfaces of the first dielectric core, second dielectric core, and the cladding; and
a second conductive ground layer in contact with bottom surfaces of the first dielectric core, second dielectric core, and the cladding.

9. The PCB of claim 8 , wherein the first and second dielectric cores have the same dielectric constant.

10. The PCB of claim 8 , wherein the first dielectric material in the first filter has a dielectric constant equal to the dielectric constant of the first dielectric core.

11. The PCB of claim 8 , wherein the second dielectric material in the first filter has a dielectric constant equal to the dielectric constant of the cladding.

12. The PCB of claim 8 , wherein the second dielectric material in the first filter has a dielectric constant higher than the dielectric constant of the cladding.

13. The PCB of claim 8 , wherein the first filter and the second filter have respective Q factors that are directly proportional to a number of transitions between the first and second dielectric materials in each filter.

14. A method of attenuating crosstalk between dielectric waveguides, the method comprising:
forming a first dielectric waveguide to carry a first frequency band;
embedding a first filter within the first dielectric waveguide to attenuate transmission of a second frequency band through the first dielectric waveguide, wherein the first filter comprises alternating sections of a first dielectric material and a second dielectric material having different dielectric constants, and wherein a length of each section of the first and second dielectric materials within the first filter is equal to a quarter of a wavelength of a central frequency of the second frequency band;
forming a second dielectric waveguide to carry the second frequency band;
embedding a second filter in the second dielectric waveguide to attenuate transmission of the first frequency band through the second dielectric waveguide, wherein the second filter comprises alternating sections of the first dielectric material and the second dielectric material, and wherein a length of each section of the first and second dielectric materials within the second filter is equal to a quarter of a wavelength of a central frequency of the first frequency band; and
disposing a cladding between the first dielectric waveguide and second dielectric waveguide, wherein the cladding has a lower dielectric constant than a dielectric constant of the first and second dielectric waveguides.

15. The method of claim 14 , wherein the first and second dielectric waveguides have the same dielectric constant.

16. The method of claim 14 , wherein the first dielectric material in the first filter has a dielectric constant equal to the dielectric constant of the first dielectric waveguide.

17. The method of claim 14 , wherein the second dielectric material in the first filter has a dielectric constant equal to the dielectric constant of the cladding.

Assignees

• IBM

Inventors

• Myers Joshua
• Hejase Jose A
• Tang Junyan
• Dreps Daniel M

Classifications

• H01P1/2002 Primary

  Dielectric waveguide filters (H01P1/212, H01P1/213, H01P1/215, H01P1/219 take precedence) · CPC title

• H05K1/0243

  Printed circuits associated with mounted high frequency components · CPC title

• H01P11/006

  Manufacturing dielectric waveguides · CPC title

• H05K1/0233

  Filters, inductors or a magnetic substance · CPC title

• H05K1/024

  Dielectric details, e.g. changing the dielectric material around a transmission line · CPC title