Layer 2 in BGA Area for DACs/ADCs

UltraScale Architecture PCB Design User Guide (UG583)

Document ID
UG583
Release Date
2023-11-14
Revision
1.27 English
Figure 3-21:      Layer 2 in BGA Area for DACs/ADCs

X-Ref Target - Figure 3-21

X22699-Layer_2_in_BGA_Area_for_DACs_and_ADCs.jpg

Signal P exists at 45° north-east. Signal N exists via the pad at due west. A neck down trace length of 78 mils with 4 mil width is needed to tune the return loss up to 6 GHz. Remove all unused pads from DACs and ADCs which are not routed on layer 2.

Air gap between the P and N signals should be 15 mil. The ground guard trace should be 18 mil wide. Air gap between signal and ground should be 15 mil. Trace routing in the BGA area should be located at the center line of the signal trace midway between the anti-pads on layer 1. In summary:

Trace width = 5.8 mils

Land pad for micro-via = 16 mils

Land pad for all grounds = 18 mils