High frequency, surface mountable microstrip band pass filter

1. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter; and

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz, and

wherein the filter exhibits a return loss that is less than about −20 dB at the frequency.

2. The filter of claim 1 , wherein the frequency is about 28 GHz.

3. The filter of claim 1 , wherein the filter exhibits an insertion loss response that is greater than −3.5 dB across a frequency range that ranges from about 27 GHz to about 29 GHz.

4. The filter of claim 1 , wherein the filter exhibits a return loss response that is less than about −10 dB from about 27 GHz to about 29 GHz.

5. The filter of claim 1 , wherein the conductive path has an effective length from the first arm of the thin-film microstrip to the port that ranges from about 95% to about 105% of λ/4, wherein λ is a wavelength that corresponds with a passband frequency propagating through the monolithic base substrate.

6. The filter of claim 1 , wherein the first arm of the first thin-film microstrip is elongated in the Y-direction, and wherein the conductive path comprises a top conductive strip that is elongated in the X-direction, the top conductive strip formed over the top surface of the monolithic base substrate and connected with each of the via and the first arm of the first thin-film microstrip.

7. The filter of claim 5 , wherein the conductive path comprises a bottom conductive strip connected with each of the via and the port.

8. The filter of claim 7 , wherein:

the top conductive strip has a top conductive strip effective length in the X-direction between the arm of the first thin-film microstrip and the via;

the bottom conductive strip has a bottom conductive strip effective length in the X-Y plane between the via and the port;

the via has a via length in a Z-direction that is perpendicular to the X-Y plane; and

the effective length of the conductive path is equal to a sum of the top conductive strip effective length, the bottom conductive strip effective length, and the via length.

9. The filter of claim 7 , wherein the bottom conductive strip is elongated in the Y-direction.

10. The filter of claim 9 , wherein the first thin-film microstrip has at least one rounded outer corner between the base portion of the first thin-film microstrip and at least one of the first arm or second arm of the first thin-film microstrip.

11. The filter of claim 9 , wherein at least one of the first arm or second arm of the first thin-film microstrip has a width that is less than about 200 microns.

12. The filter of claim 1 , wherein:

the second arm of the first thin-film microstrip is elongated in the Y-direction; and

the first arm of the second thin-film microstrip is elongated in the Y-direction and spaced apart by a first spacing distance from the first arm of the first thin-film microstrip in the X-direction by a first spacing distance that is less than about 150 microns.

13. The filter of claim 12 , wherein:

the second arm of the second thin-film microstrip is elongated in the Y-direction; and

the plurality of thin-film microstrips comprises a third thin-film microstrip, the first arm of the third thin-film microstrip being elongated in the Y-direction and spaced apart in the X-direction from the second arm of the second thin-film microstrip by a second spacing distance that is less than about 150 microns.

14. The filter of claim 13 , wherein a ratio of the second spacing distance is the first spacing distance ranges from about 1.1 to about 10.

15. The filter of claim 13 , wherein:

the first arm of the second thin-film microstrip and the second arm of the first thin-film microstrip overlap in the Y-direction along a first overlapping length;

the second arm of the second thin-film microstrip and the first arm of the third thin-film microstrip overlap in the Y-direction along a second overlapping length; and

the second overlapping length ranges from about 75% to about 96% of the first overlapping length or ranges from about 104% to about 125% of the first overlapping length.

16. The filter of claim 1 , wherein the monolithic base substrate has a bottom surface opposite the top surface, and wherein the filter further comprises a ground plane formed over the bottom surface of the base substrate.

17. The filter of claim 16 , wherein:

the ground plane has a perimeter in an X-Y plane that is parallel with the top surface of the monolithic base substrate; and

at least one of the first thin-film microstrip or second thin-film microstrip is contained within the perimeter of the ground plane of in the X-Y plane.

18. The filter of claim 1 , further comprising a cover substrate formed over the top surface of the monolithic base substrate.

19. The filter of claim 1 , wherein the monolithic base substrate has a thickness of less than about 500 microns.

20. The filter of claim 1 , wherein the monolithic base substrate comprises a material having a dielectric constant that is less than about 30 as determined in accordance with ASTM D2520-13 at an operating temperature of 25° C. and frequency of 28 GHz.

21. The filter of claim 1 , wherein the monolithic base substrate comprises alumina.

22. The filter of claim 1 , wherein a length of the filter in the X-direction is less than about 5 mm, and a width of the filter in the Y-direction is less than about 3 mm.

23. The filter of claim 1 , wherein the thin-film microstrips have thicknesses in the Z-direction that range from about 0.3 micrometers to about 10 micrometers.

24. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular to the first and second arms, and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter; and

a conductive path comprising a via formed in the monolithic base substrate, the conductive path connecting the first arm of the thin-film microstrip to the port, the conductive path having an effective length between the first arm of the thin-film microstrip and the port that ranges from about 95% to about 105% of λ/4, wherein λ is a wavelength that corresponds with a passband frequency propagating through the monolithic base substrate.

25. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter; and

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz,

wherein the first arm of the first thin-film microstrip is elongated in the Y-direction, and wherein the conductive path comprises a top conductive strip that is elongated in the X-direction, the top conductive strip formed over the top surface of the monolithic base substrate and connected with each of the via and the first arm of the first thin-film microstrip.

26. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter; and

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz,

wherein the second arm of the first thin-film microstrip is elongated in the Y-direction, and

wherein the first arm of the second thin-film microstrip is elongated in the Y-direction and spaced apart by a first spacing distance from the first arm of the first thin-film microstrip in the X-direction by a first spacing distance that is less than about 150 microns.

27. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a bottom surface opposite the top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X- direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter;

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter; and

a ground plane formed over the bottom surface of the monolithic base substrate, the ground plane having a perimeter in an X-Y plane that is parallel with the top surface of the monolithic base substrate,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz, and

wherein at least one of the first thin-film microstrip or second thin-film microstrip is contained within the perimeter of the ground plane of in the X-Y plane.

28. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter;

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter; and

a cover substrate formed over the top surface of the monolithic base substrate,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz.

29. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter; and

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz, and

wherein a length of the filter in the X-direction is less than about 5 mm and a width of the filter in the Y-direction is less than about 3 mm.

30. A high frequency, stripline filter having a bottom surface for mounting to a mounting surface, the filter comprising:

a monolithic base substrate having a top surface, a length in an X-direction, a width in a Y-direction that is perpendicular to the X-direction, and a thickness in a Z-direction that is perpendicular to each of the X-direction and Y-direction;

a plurality of thin-film microstrips comprising a first thin-film microstrip and a second thin-film microstrip, each of the plurality of thin-film microstrips having a first arm, a second arm parallel to the first arm, and a base portion connected with the first and second arms, the base portion being perpendicular each of first and second arms; and wherein the plurality of thin-film microstrips are formed over the top surface of the monolithic base substrate;

a port exposed along the bottom surface of the filter; and

a conductive path comprising a via formed in the monolithic base substrate, the conductive path electrically connecting the first thin-film microstrip with the port on the bottom surface of the filter,

wherein the filter exhibits an insertion loss that is greater than −3.5 dB at a frequency that is greater than about 15 GHz, and

wherein the thin-film microstrips have thicknesses in the Z-direction that range from about 0.3 micrometers to about 10 micrometers.