High Q planar inductors and IPD applications
Disclosed is methodology and apparatus for producing a planar inductor having a high quality (Q) factor. The inductor is formed by providing a first, relatively wide coil turn, and at least a pair of relatively more narrow second coil turns, displaced in a different plane from that occupied by the first coil turn. The configuration of such coil turns produces a high value of mutual coupling among the coil turns, resulting in an inductor having a high quality (Q) factor.
1. A planar inductor, comprising:
a substrate having upper and lower surfaces;
a first coil having a first predetermined number of turns arranged in a first plane relative to one of said surfaces of said substrate and supported on said substrate; and
a second coil having a second predetermined number of turns arranged in a second plane relative to said one of said surfaces of said substrate and supported on said substrate, said second coil being vertically aligned with said first coil in a direction perpendicular to said one of said surfaces of said substrate;
wherein said first predetermined number of turns occupies a planar area which is substantially equal to a planar area occupied by said second predetermined number of turns.
2. A planar inductor as in claim 1 , wherein the number of said second predetermined number of turns is twice the number of said first predetermined number of turns.
3. A planar inductor as in claim 1 , wherein:
said first coil has at least one turn corresponding to a conductive element having a first predetermined width; and
wherein said second coil has a plurality of turns, each of which said plurality of turns corresponds to individual planar conductors having individual widths corresponding to individual portions of said first predetermined width.
4. A planar inductor as in claim 3 , wherein said individual portions are equal.
5. A planar inductor as in claim 3 , wherein said plurality of turns are arranged with at least one central turn thereof having a width corresponding to a predetermined portion of said first predetermined width, and with the remaining of said plurality of turns having widths corresponding to progressively smaller predetermined portions of said first predetermined width.
6. A planar inductor as in claim 1 , wherein said second coil is vertically aligned above said first coil in a direction perpendicular to a common surface with said first coil.
7. A planar inductor as in claim 1 , wherein said substrate comprises a ceramic material.
8. A planar inductor as in claim 1 , wherein said substrate comprises one of a glass, glass-ceramic, quartz, and a high resistivity Si material.
9. A planar inductor as in claim 1 , wherein said substrate comprises a printed circuit board.
10. A planar inductor as in claim 1 , further comprising:
terminations associated with beginning and end portions of both of said first and second coils; and
at least one connection point associated with a mid portion of said second coil;
wherein said first coil and said second coil are electrically connected in series by way of said terminations, and wherein an inductor center-tap is provided by way of said connection point.
11. A planar inductor as in claim 1 , further comprising:
a plurality of said planar inductors supported by said substrate; and
a plurality of capacitors supported by said substrate, and configured with said plurality of planar conductors so as to form an elliptical band-pass filter.