Paddle card for crosstalk cancellation in high-speed signaling
A paddle card includes a printed circuit board and a twin-axial cable. The PCB includes a first signal pad on a top surface of the PCB and a second signal pad on a bottom surface of the PCB. The second signal pad is directly below the first signal pad. The twin-axial cable includes a first signal conductor coupled to the first signal pad and a second signal conductor coupled to the second signal pad.
1. A paddle card, comprising:
a printed circuit board (PCB) including a first signal pad on a top surface of the PCB and a second signal pad on a bottom surface of the PCB, the second signal pad being directly below the first signal pad; and
a first twin-axial cable including a first signal conductor coupled to the first signal pad and a second signal conductor coupled to the second signal pad.
2. The paddle card of claim 1 , wherein the PCB further includes a first guard trace having a first guard trace pad on the top surface and a second guard trace pad on the bottom surface, wherein the first and second guard trace pads are coupled together by a first through-hole via.
3. The paddle card of claim 2 , wherein the first twin-axial cable further includes a first drain conductor coupled to one of the first guard trace pad and the second guard trace pad.
4. The paddle card of claim 3 , wherein the PCB further includes a second guard trace having a third guard trace pad on the top surface and a fourth guard trace pad on the bottom surface, wherein the first and second guard trace pads are coupled together by a second through-hole via.
5. The paddle card of claim 4 , wherein:
the first twin-axial cable further includes a second drain conductor;
when the first drain conductor is coupled to the first guard trace pad, the second drain conductor is coupled to the fourth guard trace pad; and
when the first drain conductor is coupled to the second guard trace pad, the second drain conductor is coupled to the third guard trace pad.
6. The paddle card of claim 2 , wherein the first through-hole via is coupled to a ground plane layer of the PCB.
7. The paddle card of claim 2 , wherein the first drain conductor is hot-barwi soldered to the selected one of the first guard trace pad and the second guard trace pad.
8. The paddle card of claim 1 , wherein:
the PCB further includes a first signal trace on the top surface and a second signal trace on the top surface;
the first signal trace is coupled to the first signal pad; and
the second signal trace is coupled to the second signal pad by a through-hole via.
9. The paddle card of claim 8 , wherein the first signal conductor, the first signal pad, and the first signal trace carry a first side of a double-ended differential signal, and wherein the second signal conductor, the second signal pad, and the second signal trace carry a second side of the double-ended differential signal.
10. The paddle card of claim 1 , wherein the first signal conductor is hot-bar soldered to the first signal pad and the second signal conductor is hot-bar soldered to the second signal pad.
11. A paddle card, comprising:
a printed circuit board (PCB) including a first signal pad on a top surface of the PCB, a second signal pad on a bottom surface of the PCB, a third signal pad on the top surface, a fourth signal pad on the bottom surface, a first signal trace on the top surface coupled to the first signal pad, a second signal trace on the top surface coupled to the second signal pad by a first through-hole via, a third signal trace on the top surface coupled to the third signal pad, and a fourth signal trace on the top surface coupled to the fourth signal pad by a second through-hole via, wherein the second signal pad is directly below the first signal pad and the fourth signal pad is directly below the third signal pad;
a first twin-axial cable including a first signal conductor coupled to the first signal pad and a second signal conductor coupled to the second signal pad; and
a second twin-axial cable including a third signal conductor coupled to the third signal pad and a fourth signal conductor coupled to the fourth signal pad;
wherein the second signal trace is adjacent to the fourth signal trace.
12. A method of forming a paddle card, the method comprising:
forming, on a top surface of a printed circuit board (PCB), a first signal pad;
forming, on a bottom surface of the PCB, a second signal pad, the second signal pad being directly below the first signal pad;
coupling a first signal conductor of a first twin-axial cable to the first signal pad; and
coupling a second signal conductor of the first twin-axial cable to the second signal pad.
13. The method of claim 12 , further comprising:
forming, on the top surface, a first guard trace pad;
forming, on the bottom surface, a second guard trace pad;
coupling the first guard trace pad to the second guard trace pad by a first through-hole via.
14. The method of claim 13 , further comprising:
coupling a first drain conductor of the twin-axial cable to one of the first guard trace pad and the second guard trace pad.
15. The method of claim 14 , further comprising:
forming, on the top surface, a third guard trace pad;
forming, on the bottom surface, a fourth guard trace pad;
coupling the third guard trace pad to the fourth guard trace pad by a second through-hole via.
16. The method of claim 15 , wherein the first twin-axial cable further includes a second drain conductor, the method further comprising:
when the first drain conductor is coupled to the first guard trace contact, coupling the second drain conductor to the fourth guard trace contact; and
when the first drain conductor is coupled to the second guard trace contact, coupling the second drain conductor to the third guard trace contact.
17. The method of claim 13 , further comprising:
coupling the first through-hole via to a ground plane layer of the PCB.
18. The method of claim 13 , wherein the first drain conductor is hot-bar soldered to the selected one of the first guard trace pad and the second guard trace pad.
19. The method of claim 12 , further comprising:
forming, on the top surface, a first signal trace and a second signal;
coupling the first signal trace to the first signal pad; and
coupling the second signal trace to the second signal pad by a through-hole via.
20. The method of claim 19 , wherein the first signal conductor, the first signal pad, and the first signal trace carry a first side of a double-ended differential signal, and wherein the second signal conductor, the second signal pad, and the second signal trace carry a second side of the double-ended differential signal.