Printed circuit board having vias arranged for high speed serial differential pair data links
A printed circuit board includes a differential signal via pairs to route differential signal between layers of the printed circuit board. A first differential signal via pair is oriented in a first orientation and a second differential signal via pair is oriented perpendicular to the first orientation. The second differential signal via pair is located such that a midpoint of a first line segment drawn between centers of first and second vias of the second differential signal pair intersects a first ray drawn from a center of a first via of the first differential signal via pair through a center of a second via of the first differential signal via pair. Further, the second differential signal via pair is located such that the midpoint of the first line segment is at a characteristic via-to-via pitch distance for the printed circuit board from the center of the second via of the first differential signal via pair.
1. A printed circuit board, comprising:
a first differential signal via pair to route a first differential signal from a first layer of the printed circuit board to a second layer of the printed circuit board, wherein first and second vias of the first differential signal via pair are spaced apart from each other at a first characteristic via-to-via pitch distance for the printed circuit board;
a second differential signal via pair to route a second differential signal from the first layer to the second layer wherein first and second vias of the second differential signal via pair are spaced apart from each other at the first characteristic via-to-via pitch distance, the first differential signal via pair is oriented on the printed circuit board in a first orientation, the second differential signal via pair is oriented on the printed circuit board in a second orientation that is perpendicular to the first orientation, the second differential signal via pair is located such that a midpoint of a first line segment drawn between centers of the first and second vias of the second differential signal pair intersects a first ray drawn from a center of the first via of the first differential signal via pair through a center of the second via of the first differential signal via pair, and the second differential signal via pair is further located such that the midpoint of the first line segment is at the first characteristic via-to-via pitch distance from the center of the second via of the first differential signal via pair;
a third differential signal via pair to route a third differential signal from the first layer to the second layer wherein the third differential signal via pair is oriented on the printed circuit board in a third orientation that is perpendicular to the first orientation, the third differential signal via pair is located such that a midpoint of a second line segment drawn between centers of first and second vias of the third differential signal pair intersects a second ray drawn from the center of the second via of the first differential signal via pair through the center of the first via of the first differential signal via pair, and the third differential signal via pair is further located such that the midpoint of the third line segment is at the characteristic via-to-via pitch distance from the center of the first via of the first differential signal via pair;
a first ground via located such that a center of the first ground via is at the first characteristic via-to-via pitch distance from the center of the second via of the first differential signal via pair and at a second characteristic via-to-via pitch distance from the first via of the second differential signal via pair, and is located to a first side of the first ray, wherein the first characteristic via-to-via pitch distance is shorter than the second characteristic via-to-via pitch distances; and
a second ground via located such that a center of the second ground via is at the first characteristic via-to-via pitch distance from the center of the second via of the first differential signal via pair and at the second characteristic via-to-via pitch distance from the second via of the second differential signal via pair, and is located to a second side of the first ray, wherein the first, second, and third differential signal via pairs have a spatial efficiency of 3:1.
2. The printed circuit board of claim 1 , further comprising:
a third ground via located such that a center of the third ground via is at the second characteristic via-to-via pitch distance from the center of the first via of the first differential signal via pair and at the second characteristic via-to-via pitch distance from the first via of the third differential signal via pair, and is located to a first side of the second ray; and
a fourth ground via located such that a center of the fourth ground via is at the second characteristic via-to-via pitch distance from the center of the first via of the first differential signal via pair and at the second characteristic via-to-via pitch distance from the second via of the third differential signal via pair, and is located to a second side of the second ray.
3. The printed circuit board of claim 1 , further comprising:
a first pair of circuit traces on the first layer, the first pair of circuit traces coupled between a first device and the first differential signal via pair to communicate the first differential signal from the first device to the first differential signal via pair; and
a second pair of circuit traces on the first layer, the second pair of circuit traces coupled between the first device and the second differential signal via pair to communicate the second differential signal from the first device to the second differential signal via pair.
4. The printed circuit board of claim 3 , further comprising:
a third pair of circuit traces on the second layer, the third pair of circuit traces coupled between the first differential signal via pair and a second device to communicate the first differential signal from the first differential signal via pair to the second device; and
a fourth pair of circuit traces on the second layer, the fourth pair of circuit traces coupled between the second differential signal via pair and the second device to communicate the second differential signal from the second differential signal via pair to the second device.
5. The printed circuit board of claim 1 , wherein the first and second differential signals are high speed serial differential pair data links.
6. The printed circuit board of claim 5 , wherein the high speed serial differential pair data link includes one of a Universal Serial Bus data link, a Peripheral Component Interconnect-Express data link, a Serial-ATA data link, and a High-Definition Multimedia Interface data link.
7. An information handling system, comprising:
a processor; and
a printed circuit board including:
a first differential signal via pair to route a first differential signal from a first layer of the printed circuit board to a second layer of the printed circuit board, wherein first and second vias of the first differential signal via pair are spaced apart from each other at a first characteristic via-to-via pitch distance for the printed circuit board; and
a second differential signal via pair to route a second differential signal from the first layer to the second layer wherein first and second vias of the second differential signal via pair are spaced apart from each other at the first characteristic via-to-via pitch distance, the first differential signal via pair is oriented on the printed circuit board in a first orientation, the second differential signal via pair is oriented on the printed circuit board in a second orientation that is perpendicular to the first orientation, the second differential signal via pair is located such that a midpoint of a first line segment drawn between centers of the first and second vias of the second differential signal pair intersects a first ray drawn from a center of the first via of the first differential signal via pair through a center of the second via of the first differential signal via pair, and the second differential signal via pair is further located such that the midpoint of the first line segment is at the characteristic via-to-via pitch distance from the center of the second via of the first differential signal via pair;
a third differential signal via pair to route a third differential signal from the first layer to the second layer wherein the third differential signal via pair is oriented on the printed circuit board in a third orientation that is perpendicular to the first orientation, the third differential signal via pair is located such that a midpoint of a second line segment drawn between centers of first and second vias of the third differential signal pair intersects a second ray drawn from the center of the second via of the first differential signal via pair through the center of the first via of the first differential signal via pair, and the third differential signal via pair is further located such that the midpoint of the third line segment is at the characteristic via-to-via pitch distance from the center of the first via of the first differential signal via pair;
a first ground via located such that a center of the first ground via is at the first characteristic via-to-via pitch distance from the center of the second via of the first differential signal via pair and at a second characteristic via-to-via pitch distance from the first via of the second differential signal via pair, and is located to a first side of the first ray, wherein the first characteristic via-to-via pitch distance is shorter than the second characteristic via-to-via pitch distance; and
a second ground via located such that a center of the second ground via is at the first characteristic via-to-via pitch distance from the center of the second via of the first differential signal via pair and at the second characteristic via-to-via pitch distance from the second via of the second differential signal via pair, and is located to a second side of the first ray, wherein the first, second, and third differential signal via pairs have a spatial efficiency of 3:1.
8. The information handling system of claim 7 , the printed circuit board further comprising:
a third ground via located such that a center of the third ground via is at the second characteristic via-to-via pitch distance from the center of the first via of the first differential signal via pair and at the second characteristic via-to-via pitch distance from the first via of the third differential signal via pair, and is located to a first side of the second ray; and
a fourth ground via located such that a center of the fourth ground via is at the second characteristic via-to-via pitch distance from the center of the first via of the first differential signal via pair and at the second characteristic via-to-via pitch distance from the second via of the third differential signal via pair, and is located to a second side of the second ray.
9. The information handling system of claim 7 , the printed circuit board further comprising:
a first pair of circuit traces on the first layer, the first pair of circuit traces coupled between a first device and the first differential signal via pair to communicate the first differential signal from the first device to the first differential signal via pair; and
a second pair of circuit traces on the first layer, the second pair of circuit traces coupled between the first device and the second differential signal via pair to communicate the second differential signal from the first device to the second differential signal via pair.
10. The information handling system of claim 9 , the printed circuit board further comprising:
a third pair of circuit traces on the second layer, the third pair of circuit traces coupled between the first differential signal via pair and a second device to communicate the first differential signal from the first differential signal via pair to the second device; and
a fourth pair of circuit traces on the second layer, the fourth pair of circuit traces coupled between the second differential signal via pair and the second device to communicate the second differential signal from the second differential signal via pair to the second device.
11. The information handling system of claim 7 , wherein the first and second differential signals are high speed serial differential pair data links.
12. The information handling system of claim 11 , wherein the high speed serial differential pair data link includes one of a Universal Serial Bus data link, a Peripheral Component Interconnect-Express data link, a Serial-ATA data link, and a High-Definition Multimedia Interface data link.