Printed circuit board, optical module, and optical transmission equipment
Provided is a printed circuit board realizing selective inhibition of electromagnetic noise and enabling high-density arrangement of differential transmission lines without increasing cost. The printed circuit board includes a pair of strip conductors (first layer), a first resonance conductor plate, a ground conductive layer (together with a second layer) including an opening portion, a second resonance conductor plate (third layer), a third resonance conductor plate (fourth layer), first via holes connecting the first and second resonance conductor plates, a second via hole connecting the second and third resonance conductor plates, and third via holes connecting the third resonance conductor plate and the ground conductive layer, wherein a polygon obtained by sequentially connecting centers of the adjacent third via holes overlaps so as to include the first resonance conductor plate, and center-to-center distance between the adjacent third via holes is 0.5 wavelength or less at frequency corresponding to the bit rate.
1. A printed circuit board comprising:
a pair of strip conductors extending in a first direction;
a first resonance conductor, below, and overlapping with, the pair of strip conductors;
a ground layer, surrounding, and in plane with, the first resonance conductor;
a second resonance conductor, below and overlapping with, the first resonance conductor,
the second resonance conductor including a first via to the first resonance conductor; and
a third resonance conductor, below the second resonance conductor and overlapping with the first resonance conductor,
the third resonance conductor including:
a second via to the second resonance conductor, and
a plurality of third vias connecting to the ground layer,
wherein the plurality of third vias surround the first resonance conductor.
2. The printed circuit board according to claim 1 , wherein the first resonance conductor has a shape that is substantially line-symmetrical with respect to a centerline of the pair of strip conductors.
3. The printed circuit board according to claim 1 , wherein the second resonance conductor has a shape that is substantially line-symmetrical with respect to a centerline of the pair of strip conductors.
4. The printed circuit board according to claim 1 , wherein a distance between adjacent third vias of the plurality of third vias is 0.5 wavelength or less at a frequency corresponding to a bit rate of a digital modulation signal to be transmitted.
5. The printed circuit board according to claim 4 , wherein the distance is a center-to-center distance between the adjacent third vias.
6. The printed circuit board according to claim 1 , wherein the second via is arranged at a center of the second resonance conductor in plan view.
7. The printed circuit board according to claim 1 , wherein the ground layer comprises an opening portion that surrounds the first resonance conductor.
8. A printed circuit board comprising:
a plurality of strip conductor pairs in a first layer,
each strip conductor pair, of the plurality of strip conductor pairs, extending in a first direction;
a plurality of first resonance conductors in a second layer below the first layer,
each first resonance conductor, of the plurality of first resonance conductors, overlapping with a corresponding strip conductor pair of the plurality of strip conductor pairs;
a ground in the second layer, surrounding and shared amongst each first resonance conductor of the plurality of first resonance conductors;
a plurality of second resonance conductors in a third layer below the second layer,
each second resonance conductor, of the plurality of second resonance conductors, overlapping with a corresponding first resonance conductor of the plurality of first resonance conductors, and
each second resonance conductor including a first via to the corresponding first resonance conductor;
a plurality of third resonance conductors in a fourth layer below the third layer,
each third resonance conductor, of the plurality of third resonance conductors, overlapping with a respective first resonance conductor of the plurality of first resonance conductors, and
each third resonance conductor including a second via to a respective second resonance conductor; and
a plurality of third vias connecting the fourth layer and the ground,
wherein a set of third vias, of the plurality of third vias, surrounds each first resonance conductors of the plurality of first resonance conductors.
9. The printed circuit board according to claim 8 , wherein a first set of third vias, of the plurality of third vias, surrounds a first particular resonance conductor of the plurality of first resonance conductors,
wherein a second set of third vias, of the plurality of third vias, surrounds a second particular resonance conductor of the plurality of first resonance conductors, and
wherein the first set of third vias and the second set of third vias comprise a common set of vias.
10. The printed circuit board according to claim 8 , wherein a lane pitch between adjacent strip conductor pairs of the plurality of strip conductor pairs is equal to a distance between adjacent third vias of the plurality of third vias.
11. The printed circuit board according to claim 8 , wherein a lane pitch between adjacent strip conductor pairs of the plurality of strip conductor pairs is 1.2 mm.
12. The printed circuit board according to claim 8 , wherein a first particular resonance conductor, of the plurality of first resonance conductors, is offset in the first direction from a second particular resonance conductor of the plurality of first resonance conductors.
13. The printed circuit board according to claim 12 , wherein a length of the offset is 2.85 mm.
14. The printed circuit board according to claim 8 , wherein the second layer comprises a plurality of opening portions,
wherein each opening portion, of the plurality of opening portions, surrounds a corresponding first resonance conductor of the plurality of first resonance conductors.
15. The printed circuit board according to claim 8 , wherein a distance between adjacent third vias of the plurality of third vias is 0.5 wavelength or less at a frequency corresponding to a bit rate of a digital modulation signal to be transmitted.
16. An optical module, comprising:
a printed circuit board comprising:
a pair of strip conductors extending in a first direction;
a first resonance conductor, below, and overlapping with, the pair of strip conductors;
a ground layer, surrounding, and in plane with, the first resonance conductor;
a second resonance conductor, below and overlapping with, the first resonance conductor,
the second resonance conductor including a first via to the first resonance conductor; and
a third resonance conductor, below the second resonance conductor and overlapping with the first resonance conductor,
the third resonance conductor including:
a second via to the second resonance conductor, and
a plurality of third vias connecting to the ground layer,
wherein the plurality of third vias surround the first resonance conductor.
17. The optical module according to claim 16 , wherein the first resonance conductor has a shape that is substantially line-symmetrical with respect to a centerline of the pair of strip conductors.
18. The optical module according to claim 16 , wherein the second resonance conductor has a shape that is substantially line-symmetrical with respect to a centerline of the pair of strip conductors.
19. The optical module according to claim 16 , wherein a distance between adjacent third vias of the plurality of third vias is 0.5 wavelength or less at a frequency corresponding to a bit rate of a digital modulation signal to be transmitted.
20. The optical module according to claim 16 , wherein the ground layer comprises an opening portion that surrounds the first resonance conductor.