Xilinx Virtex-5 RocketIO GTP User Manual

Virtex-5 RocketIO GTP Transceiver User Guide www.xilinx.com 243
UG196 (v1.3) May 25, 2007
Differential Vias
R
Differential Vias
The most common transition is the differential via where the signal pair must transition
from an upper stripline layer or top microstrip to a lower stripline layer or bottom
microstrip.
Figure 13-13 shows a Ground-Signal-Signal-Ground (GSSG) type differential via. Ground
vias are connected to each ground plane in the stackup, while signal layers only contain
pads for the entry and exit layers.
Figure 13-11: 840 fF Excess Capacitance with Ground Plane Intact
Figure 13-12: 57 fF Excess Capacitance with Ground Plane Intact
550
500
450
400
350
300
0.55 0.60 0.65 0.70 0.80 0.90 0.95 1.000.850.75
Time, ns
m1
VtdrPlaneNotCleared, mV
VtdrPlaneCleared, mV
UG196_c13_11_051406
m2
550
500
450
400
350
300
0.55 0.60 0.65 0.70 0.80 0.90 0.95 1.000.850.75
Time, ns
m1
VtdrPlaneNotCleared, mV
VtdrPlaneCleared, mV
UG196_c13_12_051406
m2

Xilinx Virtex-5 RocketIO GTP Specifications

General

Brand	Xilinx
Model	Virtex-5 RocketIO GTP
Category	Transceiver
Language	English