Tunable hybrid EBG-based electronic filter with discrete reactive elements

1 . A radio frequency (RF) filter comprising:

a ground plane;

a top conductor overlying the ground plane, the top conductor having an input and an output for receiving and outputting signals, respectively;

a first unit cell comprising:

a first planar structure disposed between the top conductor and the ground plane; and

a first pair of vias connecting the first planar structure to the ground plane; and

a second unit cell comprising:

a second planar structure disposed between the top conductor and the ground plane; and

a second pair of vias connecting the second planar structure to the ground plane; and

at least one discrete reactive element connected to the top conductor and arranged in a shunt configuration with the top conductor, wherein a first end of the at least one discrete reactive element is connected to a portion of the top conductor that overlies the first planar structure or the second planar structure and a second end of the at least one discrete reactive element is connected to the ground plane.

2 . The RF filter of claim 1 , wherein the at least one discrete reactive element includes a capacitor.

3 . The RF filter of claim 1 , wherein the at least one discrete reactive element includes an inductor.

4 . An apparatus comprising:

a ground plane;

a top conductor overlying the ground plane, the top conductor having an input and an output for receiving and outputting signals, respectively;

at least one discrete reactive element connected to the top conductor and arranged in a shunt configuration with the top conductor; and

a plurality of unit cells arranged in series along the top conductor, wherein each of the plurality of unit cells includes:

a planar structure disposed between the top conductor and the ground plane; and

a pair of vias connecting the planar structure to the ground plane;

wherein a first end of the at least one discrete reactive element is connected to a portion of the top conductor that overlies one of the planar structures and a second end of the at least one discrete reactive element is connected to the ground plane.

5 . The apparatus of claim 4 , wherein:

the plurality of unit cells are geometrically tapered in a first direction such that a width of a first unit cell of the plurality of unit cells is less than a width of a second unit cell of the plurality of unit cells;

the at least one discrete reactive element includes a first discrete reactive element and a second discrete reactive element, the first discrete reactive element being connected to a first portion of the top conductor that is aligned with the first unit cell and the second discrete reactive element being connected to a second portion of the top conductor that is aligned with the second unit cell; and

reactance values of the at least one discrete reactive element are tapered in the first direction such that a reactance value of the first discrete reactive element is less than a reactance value of the second discrete reactive element.

6 . The apparatus of claim 5 , wherein:

the plurality of unit cells are further geometrically tapered in a second direction such that a width of a third unit cell of the plurality of unit cells is less than the width of the second unit cell;

the at least one discrete reactive element further includes a third discrete reactive element connected to a third portion of the top conductor that is aligned with the third unit cell; and

the reactance values of the at least one discrete reactive element are further tapered in the second direction such that a reactance value of the third discrete reactive element is less than the reactance value of the second discrete reactive element.

7 . The apparatus of claim 4 , wherein the at least one discrete reactive element includes a capacitor.

8 . The apparatus of claim 4 , wherein the at least one discrete reactive element includes an inductor.

9 . The apparatus of claim 4 , wherein the top conductor includes at least one inter-cell path between portions of the top conductor that overlie neighboring cells of the plurality of unit cells, and wherein the at least one inter-cell path is non-linear.

10 . The apparatus of claim 4 , wherein the pair of vias of a unit cell of the plurality of unit cells includes a first via connected to a first side of the planar structure and a second via connected to a second side of the planar structure, and wherein, for the unit cell, the top conductor overlies a center portion of the planar structure that separates the first side and the second side of the planar structure and the top conductor overlies an entirety of the planar structure.

11 . The apparatus of claim 4 , further comprising:

a dielectric layer disposed between the top conductor and the ground plane, wherein each of the plurality of unit cells is at least partially encapsulated by the dielectric layer.

12 . A method of filtering a signal, the method comprising:

receiving the signal at an input of a top conductor, the top conductor overlying a ground plane, wherein at least one discrete reactive element is connected to the top conductor and is arranged or a shunt configuration with the top conductor;

passing the signal through a plurality of unit cells arranged in series along the top conductor, wherein each of the plurality of unit cells includes:

a planar structure disposed between the top conductor and the ground plane; and

a pair of vias connecting the planar structure to the ground plane; and

outputting the signal at an output of the top conductor;

wherein a first end of the at least one discrete reactive element is connected to a portion of the top conductor that overlies one of the planar structures and a second end of the at least one discrete reactive element is connected to the ground plane.

13 . The method of claim 12 , wherein the pair of vias of a unit cell of the plurality of unit cells includes a first via connected to a first side of the planar structure and a second via connected to a second side of the planar structure.

14 . The method of claim 13 , wherein, for the unit cell, the top conductor overlies a center portion of the planar structure that separates the first side and the second side of the planar structure.

15 . The method of claim 13 , wherein, for the unit cell, the first via is connected near a center of a first outer edge on the first side of the planar structure, and the second via is connected near a center of a second outer edge on the second side of the planar structure.

16 . The method of claim 12 , further comprising:

passing the signal through at least one inter-cell path of the top conductor, wherein the at least one inter-cell path is between portions of the top conductor that overlie neighboring cells of the plurality of unit cells, and wherein the at least one inter-cell path is non-linear.