USB, PCIe, and UFS
Jetson AGX Xavier Series Product
DG-09840-001_v2.5 | 55
Parameter
Requirement
Units
Notes
•
Use zig-zag route
instead of straight to
minimize skew, this is
a mandatory for PCIe
gen4 design
Spacing
Trace Spacing (Stripline)
Pair – Pair
To plane and capacitor pad
To unrelated high-speed signals
4x
4x
4x
Dielectric
TX and RX should not be routed on the
same layer. If this is required in a design,
they should not be interleaved, and the
spacing between the closest RX and TX
lanes must be 9x Dielectric spacing.
Length/Skew
Breakout region (Max Length)
41.9
ps
Minimum width and spacing. 4x or wider
dielectric height spacing is preferred
Trace loss budget (for carrier board routing)
Routing direct to device
Routing to PCIe/M.2 connector
-19
-
13.5
dB/in
@ 4GHz (See TBD),
Loss: GEN4 budget – module – end device
(-28dB + 5dB + 4dB)
Loss: GEN3 budget – module – end device
(-28dB + 5dB + 9.5dB)
Max trace length (delay)
Direct to device on carrier board
Stripline
Microstrip
Routed to PCIe or M.2 connector
Stripline
Microstrip
357 (2463)
328 (1939)
254 (1750)
233 (1378)
in (ps)
Mid-loss PCB of 1.47dB/in (Microstrip) or
1.35dB/in (Stripline) is used. Also,
6.9ps/mm for Stripline routing and
5.9ps/mm for Microstrip.
Max PCB via distance from the
Device/Connector
41.9
ps
Max distance from Device ball or Connector
pin to first PCB via.
PCB within pair (intra-pair) skew
0.15 (0.5)
mm (ps)
Do trace length matching before hitting
discontinuities.
Within pair (intra-pair) matching between
subsequent discontinuities
0.15 (0.5)
mm (ps)
Differential pair uncoupled length
41.9
ps
Via
Via placement
Place
GND
vias as symmetrically as possible to data pair vias.
GND
via distance should
be placed less than 1x the diff pair via pitch
Max # of Vias
4
Use micro via or back drilled via - no via stub
allowed.
Max Via stub length
na
Not Allowed
AC Cap
Value
Min/Max
0.22
uF
20%, 0402 X5R or better. Only required
for TX pair when routed to connector.
Place close to TX side.
Voiding
Voiding the plane directly under
the pad 3-4 mils larger than the
pad size is required.
Serpentine (See USB 3.1 Guidelines)
Miscellaneous
GND fill rule
Remove unwanted GND fill that is either floating or act like antenna