Compact, high-power thin-film filter
A thin-film filter may include a monolithic substrate and a patterned conductive layer formed over the monolithic substrate. The patterned conductive layer may include at least one thin-film inductor. The thin-film filter may have a power capacity that is greater than about 25 W. In some embodiments, the thin-film inductor(s) may be connected between the input port and the output port. A heat sink terminal may be exposed along the bottom surface of thin-film filter. In some embodiments, the heat sink terminal may have an exposed heat sink area, and the bottom surface of the thin-film filter has an area that is less than 20 times larger than the exposed heat sink area.
1. A thin-film filter comprising:
a monolithic substrate;
a patterned conductive layer formed over the monolithic substrate, the patterned conductive layer comprising at least one thin-film inductor; and
a heat sink terminal exposed on a bottom surface of the filter, the heat sink terminal having an exposed heat sink area;
wherein a footprint area of the filter is less than 20 times larger than the exposed heat sink area; and
wherein the thin-film filter has a power capacity that is greater than about 25 W.
2. The thin-film filter of claim 1 , wherein the footprint area is less than about 50 cm 2 .
3. The thin-film filter of claim 1 , wherein the thin-film filter has an area power capacity that is greater than about 0.02 W/mm 2 .
4. The thin-film filter of claim 1 , wherein the thin-film inductor has a thickness that is greater than about 30 micrometers.
5. The thin-film filter of claim 1 , wherein the thin-film filter exhibits an attenuation that is less than −30 dB above a stop band frequency.
6. The thin-film filter of claim 1 , further comprising:
an input port exposed on a bottom surface of the filter, the input port having an exposed input port area; and
an output port exposed on the bottom surface of the filter, the output port having an exposed output port area;
wherein the footprint area of the filter is less than 20 times larger than a total exposed area of the exposed input port area, the exposed output port area, and the exposed heat sink area.
7. The thin-film filter of claim 6 , wherein the at least one thin-film inductor comprises a plurality of thin-film inductors connected in series between the input port and the output port.
8. The thin-film filter of claim 1 , wherein the at least one thin-film inductor comprises at least two patterned conductive layers spaced apart from each other in a thickness direction of the thin-film filter.
9. The thin-film filter of claim 1 , further comprising:
an additional patterned conductive layer spaced apart from the patterned conductive layer in a thickness direction of the thin-film filter, the additional patterned conductive layer forming a capacitor with the patterned conductive layer and the heat sink terminal.
10. The thin-film filter of claim 1 , wherein the monolithic substrate comprises sapphire.
11. The thin-film filter of claim 1 , wherein the monolithic substrate has a thermal conductivity of greater than 20 W/m·° C.
12. The thin-film filter of claim 1 , wherein the at least one thin-film inductor comprises a patterned conductive layer shaped in a loop that is formed entirely on a single layer.
13. A method for forming a thin-film filter comprising:
providing a monolithic substrate;
forming a patterned conductive layer formed over the monolithic substrate, the patterned conductive layer comprising at least one thin-film inductor, the at least one thin-film inductor connected between an input port exposed on a bottom surface of the thin-film filter and an output port exposed on the bottom surface of the thin-film filter; and
forming a heat sink terminal exposed along the bottom surface of the thin-film filter, the heat sink terminal having an exposed heat sink area;
wherein a footprint area of the filter is less than 20 times larger than the exposed heat sink area.
14. A thin-film filter comprising:
a monolithic substrate;
an input port exposed on a bottom surface of the thin-film filter;
an output port exposed on the bottom surface of the thin-film filter;
a patterned conductive layer formed over the monolithic substrate, the patterned conductive layer comprising at least one thin-film inductor, the at least one thin-film inductor connected between the input port and the output port; and
a heat sink terminal exposed along the bottom surface of the thin-film filter;
wherein the heat sink terminal has an exposed heat sink area, and wherein a footprint area of the thin-film filter is less than 20 times larger than the exposed heat sink area.
15. The thin-film filter of claim 14 , wherein the thin-film filter exhibits an attenuation that is less than −30 dB above a stop band frequency.
16. The thin-film filter of claim 14 , wherein the footprint area is less than about 50 cm 2 .
17. The thin-film filter of claim 14 , wherein the thin-film filter has an area power capacity that is greater than about 0.02 W/mm 2 .
18. The thin-film filter of claim 14 , wherein the thin-film inductor has a thickness that is greater than about 30 micrometers.
19. The thin-film filter of claim 14 , wherein:
the input port has an exposed input port area;
the output port has an exposed output port area; and
the footprint area of the filter is less than 20 times larger than a total exposed area of the exposed input port area, the exposed output port area, and the exposed heat sink area.
20. The thin-film filter of claim 14 , wherein the heat sink terminal has a heat sink length in a first direction and the monolithic substrate has a length in the first direction that is less than twice the heat sink length.
21. The thin-film filter of claim 20 , wherein the at least one thin-film inductor comprises a plurality of thin-film inductors connected in series between the input port and the output port.
22. The thin-film filter of claim 20 , further comprising an additional patterned conductive layer spaced apart from the patterned conductive layer in a thickness direction of the thin-film filter, the additional patterned conductive layer forming a capacitor with the patterned conductive layer and the heat sink terminal.
23. The thin-film filter of claim 14 , wherein the monolithic substrate comprises sapphire.
24. The thin-film filter of claim 14 , wherein the monolithic substrate has a thermal conductivity of greater than 20 W/m·° C.
25. The thin-film filter of claim 14 , wherein the at least one thin-film inductor comprises a patterned conductive layer shaped in a loop that is formed entirely on a single layer.
26. The thin-film filter of claim 14 , wherein the at least one thin-film inductor comprises at least two patterned conductive layers spaced apart from each other in a thickness direction of the thin-film filter.