Apparatus and method for impedance balancing of long radio frequency (RF) via

1. A printed circuit board (PCB) apparatus, comprising:

a plurality of printed circuit board (PCB) layers (L 3 -L 19 ) forming a stack of PCB layers having formed therein a primary longitudinal structure ( 221 ) forming a radio frequency (RF) via ( 220 ) including a principal tuning section ( 223 ) and a constant longitudinal structure ( 227 ) along a conductive column support ( 255 ) journaled through the PCB layers (L 3 -L 19 ) in the via ( 220 ), the principal tuning section ( 223 ) comprising:

a first principal tuning sub-assembly ( 229 A) formed in a first portion of the RF via ( 220 ) located above the constant longitudinal structure ( 227 ) and at a first or entrance end of the primary longitudinal structure ( 221 ) and comprising a first set of pad, anti-pad pairs ( 445 , 545 , 645 ) tuned to receive and pass an RF band and pads of the first set of pad, anti-pad pairs have varying radii; and

a second principal tuning sub-assembly ( 229 B) formed in a second portion of the RF via ( 220 ) below the constant longitudinal structure ( 227 ) and at a second or exit end of the primary longitudinal structure ( 221 ) and comprising a second set of pad, anti-pad pairs ( 445 , 545 , 645 ) tuned to receive and pass the RF band and mirroring the first set of pad, anti-pad pairs ( 445 , 545 , 645 ).

2. The apparatus according to claim 1 , wherein the first principal tuning sub-assembly ( 229 A) includes independently configurable via virtual boundary dimensions along each PCB layer of the first portion of the RF via ( 220 ) at which to place at least one cage via ( 442 ); and the second principal tuning sub-assembly ( 229 B) includes independently configurable virtual boundary dimensions along each PCB layer within the second portion of the RF via ( 220 ).

3. The apparatus according to claim 2 , wherein the first principal tuning sub-assembly ( 229 A) includes independently configurable pad, anti-pad pair dimensions along said each PCB layer of the first portion of the RF via ( 220 ); and the second principal tuning sub-assembly ( 229 B) includes independently configurable pad/anti-pad pair dimensions along said each PCB layer within the second portion of the RF via ( 220 ).

4. The apparatus according to claim 3 , wherein the constant longitudinal structure ( 227 ) comprises a third portion of the RF via ( 220 ) wherein the pad, anti-pad dimensions for each PCB layer (L 7 -L 15 ) in the third portion are equal.

5. The apparatus according to claim 3 , wherein:

each PCB layer (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (GL 3 -GL 19 ), the ground layer having a first virtual via boundary and a second via annulus;

the first via boundary and the second via annulus have different radii relative to a center of the RF via;

the RF via ( 220 ) further comprising a plurality of cage vias ( 442 ) tangentially arranged relative to and around the first virtual via boundary and within the dielectric layer; and

each cage via ( 442 ) on a respective one PCB layer is equidistant from a pad of the pad/anti-pad pair of the same PCB layer.

6. The apparatus according to claim 5 , wherein the pad having a thickness corresponding to a thickness of the ground layer.

7. A tangible and non-transitory computer readable medium having program instructions which when executed by one or more processors causes the one or more processors to:

model a radio frequency (RF) via having a via hole formed in a plurality of printed circuit board (PCB) layers (L 3 -L 19 ), the via hole having a center conductive support column, a primary longitudinal structure ( 221 ) comprising a constant longitudinal structure ( 227 ), a first principal tuning sub-assembly ( 229 A) formed in a first portion of the RF via ( 220 ) located above the constant longitudinal structure ( 227 ) and at a first or entrance end of the primary longitudinal structure ( 221 ) and comprising a first set of pad, anti-pad pairs ( 445 , 545 , 645 ) to receive and pass an RF band, and a second principal tuning sub-assembly ( 229 B) formed in a second portion of the RF via ( 220 ) below the constant longitudinal structure ( 227 ) and at a second or exit end of the primary longitudinal structure ( 221 ) and comprising a second set of pad, anti-pad pairs ( 445 , 545 , 645 ) tuned to receive and pass the RF band and mirroring the first set of pad, anti-pad pairs ( 445 , 545 , 645 );

tune the model by independently changing radii of one or more pad, anti-pad pairs of the first set of pad, anti-pad pairs ( 445 , 545 , 645 );

tune the model by mirroring the changes to the radii in the first set of pad, anti-pad pairs in the second set of pad, anti-pad pairs ( 445 , 545 , 645 );

determine whether the tuned first set of pad, anti-pad pairs ( 445 , 545 , 645 ) and the tuned second set of pad, anti-pad pairs ( 445 , 545 , 645 ) are symmetrically tuned to the RF band; and

repeat the tuning of the model using the first set of pad, anti-pad pairs ( 445 , 545 , 645 ) and the second set of pad, anti-pad pairs ( 445 , 545 , 645 ) until a level of tuning is achieved.

8. The computer readable medium according to claim 7 , wherein each PCB layer of the plurality of PCB layers (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (GL 3 -GL 19 ), the ground layer having a first virtual via boundary and a second via annulus; the first virtual via boundary and the second via annulus have different radii relative to a center of the RF via ( 220 ); and each pad, anti-pad pair is independently adjustable relative to the first via boundary and the second via annulus.

9. The computer readable medium according to claim 7 , wherein each PCB layer of the plurality of PCB layers (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (GL 3 -GL 19 ), the ground layer having a first virtual via boundary and a second via annulus; the first via boundary and the second via annulus have different radii relative to a center of the RF via ( 220 ); the RF via ( 220 ) further comprising a plurality of cage vias ( 442 ) tangentially arranged relative to and around the first via boundary of each PCB layer within the dielectric layer; and wherein the model further comprises a plurality of cage vias ( 442 ) on each dielectric layer surrounding the first via boundary, and wherein the program instructions further to cause the one or more processors to:

vary a first amount of distance of the plurality of cage vias ( 442 ) on a respective one PCB layer equidistant from a pad of the pad/anti-pad pair of the same PCB layer of the first principal tuning sub-assembly ( 229 A) to tune the model to the RF band and those cage vias ( 442 ) on remaining PCB layers of the first principal tuning sub-assembly;

vary a second amount of distance of the plurality of cage vias ( 442 ) on a respective one PCB layer equidistant from a pad of the pad/anti-pad pair of the same PCB layer of the second principal tuning sub-assembly ( 229 B) to tune the model to the RF band and those cage vias ( 442 ) on remaining PCB layers of the second principal tuning sub-assembly wherein the first amount of distance and the second amount of distance is the same amount; and

repeat the varying of the distance of those cage vias ( 442 ) to adjust the level of tuning to the RF band.

10. The computer readable medium according to claim 9 , wherein the instructions executed by the one or more processors to vary of the first amount of distance of the plurality of cage vias ( 442 ) further comprising instructions to vary the first via boundary relative to a pad associated with the ground layer of the same PCB layer.

11. The computer readable medium according to claim 10 , wherein the instructions executed by the one or more processors to model the RF via ( 220 ) having the via hole with the center conductive support column further comprising instructions to form a dumbbell pattern along the center conductive support column with the first principal tuning sub-assembly ( 229 A) and the second principal tuning sub-assembly ( 229 B) at opposite ends of the center conductive support column and mirrored relative to each other.

12. The computer readable medium according to claim 7 , wherein each PCB layer of the plurality of PCB layers (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (GL 3 -GL 19 ), the ground layer having a first virtual via boundary and a second via annulus; the first via boundary and the second via annulus have different radii relative to a center of the RF via ( 220 ); the constant longitudinal structure ( 227 ) comprises a third portion of the RF via ( 220 ) comprises a subset of PCB layers (L 7 -L 15 ) of the plurality of PCB layers (L 3 -L 19 ) wherein the instructions executed by the one or more processor to model the RF via ( 220 ) further comprising instructions to:

vary the radius of the first virtual via boundary of each PCB layer of the constant longitudinal structure ( 227 ) to have a first radii; and

vary the radius of the second via annulus of each PCB layer of the constant longitudinal structure ( 227 ) to have a second radii different from the first radii.

13. The computer readable medium according to claim 7 , wherein the instructions which when executed to tune the first set of pad, anti-pad pairs ( 445 , 545 , 645 ) and tune the second set of pad, anti-pad pairs ( 445 , 545 , 645 ) include instructions to create matched impendence balancing along a pathway of the RF via ( 220 ).

14. A method comprising:

modelling a radio frequency (RF) via having a via hole formed in a plurality of printed circuit board (PCB) layers (L 3 -L 19 ), the via hole having a center conductive support column, a primary longitudinal structure ( 221 ) comprising a constant longitudinal structure ( 227 ), a first principal tuning sub-assembly ( 229 A) formed in a first portion of the RF via ( 220 ) located above the constant longitudinal structure ( 227 ) and at a first or entrance end of the primary longitudinal structure ( 221 ) and comprising a first set of pad, anti-pad pairs ( 445 , 545 , 645 ) to receive and pass an RF band, and a second principal tuning sub-assembly ( 229 B) formed in a second portion of the RF via ( 220 ) below the constant longitudinal structure ( 227 ) and at a second or exit end of the primary longitudinal structure ( 221 ) and comprising a second set of pad, anti-pad pairs ( 445 , 545 , 645 ) tuned to receive and pass the RF band and mirroring the first set of pad, anti-pad pairs;

tuning the RF via ( 220 ) by independently changing radii of one or more pad, anti-pad pairs of the first set of pad, anti-pad pairs ( 445 , 545 , 645 );

tuning the RF via ( 220 ) by mirroring the changes to the radii in the first set of pad, anti-pad pairs in the second set of pad, anti-pad pairs ( 445 , 545 , 645 );

determining whether the tuned first set of pad, anti-pad pairs ( 445 , 545 , 645 ) and the tuned second set of pad, anti-pad pairs ( 445 , 545 , 645 ) are symmetrically tuned to the RF band; and

repeating the tuning of the RF via ( 220 ) using the first set of pad, anti-pad pairs ( 445 , 545 , 645 ) and the second set of pad, anti-pad pairs ( 445 , 545 , 645 ) until a level of tuning is achieved.

15. The method according to claim 14 , wherein each PCB layer of the plurality of PCB layers (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (GL 3 -GL 19 ), the ground layer having a first virtual via boundary and a second via annulus; the first via boundary and the second via annulus have different radii relative to a center of the RF via ( 220 ); and each pad, anti-pad pair is independently adjustable relative to the second via annulus.

16. The method according to claim 14 , wherein each PCB layer of the plurality of PCB layers (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (GL 3 -GL 19 ), the ground layer having a first virtual via boundary and a second via annulus; the first via boundary and the second via annulus have different radii relative to a center of the RF via ( 220 ); and the RF via ( 220 ) further comprising a plurality of cage vias ( 442 ) tangentially arranged relative to and around the first via boundary of each PCB layer; and wherein the RF via ( 220 ) further comprises a plurality of cage vias ( 442 ) on each dielectric layer surrounding the first via boundary, and wherein the method comprises:

varying a first amount of distance of the plurality of cage vias ( 442 ) on a respective one PCB layer equidistant from a pad of the pad/anti-pad pair of the same PCB layer of the first principal tuning sub-assembly to tune the RF via ( 220 ) to the RF band and those cage vias ( 442 ) on remaining PCB layers of the first principal tuning sub-assembly ( 229 A);

varying a second amount of distance of the plurality of cage vias ( 442 ) on a respective one PCB layer equidistant from a pad of the pad/anti-pad pair of the same PCB layer of the second principal tuning sub-assembly to tune the RF via ( 220 ) to the RF band and those cage vias ( 442 ) on remaining PCB layers of the second principal tuning sub-assembly ( 229 B) wherein the first amount of distance and the second amount of distance is the same amount; and

repeating the varying of the distance of those cage vias ( 442 ) to adjust the level of tuning to the RF band.

17. The method according to claim 16 , wherein the varying of the first amount of distance of the plurality of cage vias ( 442 ) further comprising varying the first via boundary relative to a pad associated with the ground layer of the same PCB layer.

18. The method according to claim 17 , wherein the modelling of the RF via ( 220 ) having the via hole with the center conductive support column further comprising forming a dumbbell pattern along the center conductive support column with the first principal tuning sub-assembly ( 229 A) and the second principal tuning sub-assembly ( 229 B) at opposite ends of the center conductive support column and mirrored relative to each other.

19. The method according to claim 14 , wherein each PCB layer of the plurality of PCB layers (L 3 -L 19 ) comprises a dielectric layer (DL 3 -DL 19 ) and a ground layer (DL 3 -DL 19 ), the ground layer having a first virtual via boundary and a second via annulus; the first via boundary and the second via annulus have different radii relative to a center of the RF via ( 220 ); the constant longitudinal structure ( 227 ) comprises a third portion of the RF via ( 220 ) comprises a subset of PCB layers (L 7 -L 15 ) of the plurality of PCB layers (L 3 -L 19 ) wherein the modelling the RF via ( 220 ) further comprising:

varying the radius of the first via boundary of each PCB layer of the constant longitudinal structure ( 227 ) to have a first radii; and

varying the radius of the second via annulus of the ground layer of each PCB layer of the constant longitudinal structure ( 227 ) to have a second radii different from the first radii.

20. The method according to claim 14 , wherein the tuning the first set of pad, anti-pad pairs ( 445 , 545 , 645 ) and tuning the second set of pad, anti-pad pairs ( 445 , 545 , 645 ) include creating matched impendence balancing along a pathway of the RF via ( 220 ).