Transcript Layout Recommendations (cont`d)

Designing for
DVI
General Applications
Considerations
1
Design Issues to Consider
• Layout Recommendations
• Power supply considerations
• EMC considerations
2
Layout Recommendations
• Route differential pairs together
• Avoid excessive or asymmetric vias
3
Layout Recommendations (cont’d)
• Series damping resistors on data, clock,
control signal inputs to TX
GPU
• Reduces signal ringing, noise
4
Layout Recommendations (cont’d)
• Four layer PCB
- Solid ground plane
Signal
IC
IC
Signal Lines
GND
Cut in GND
or poor HF contact
Common-Mode
Current
5
Layout Considerations (cont’d)
High Emissions
Low Emissions
Signal
Return Current
Trace
Return Current
GND Plane
6
GND Plane
Signal
Power Supply Considerations
• Voltage regulator on TX PVCC supply
+5V
Switch-mode
Power Supply
+3.3V
Switching Noise
~45-60KHz
• Switching noise can cause PLL jitter
- VREG greatly reduces supply noise
7
PVCC, PVCC2
EMC Considerations
• Even though PanelLink operates at over 1GHz,
most emissions are still caused by parallel
data
• Some high frequency emissions near 1GHz
are possible, but are related to mechanical
contact
8
EMC Considerations: Data Lines
• Damping resistors, short data path
Minimize
Length
9
EMC Considerations: Ground Contact
Good contact between
Shield and connector
Shell
Broad contact
Between connector
And Bracket
Solid contact between
Bracket and chassis
Good, broad contact between connector shells and the I/O bracket
Broad contact between the I/O bracket and the system chassis
o
Good 360 contact between connector shell and cable shield
Good contact between motherboard GND and chassis
Helps with high frequency emissions
10
EMC Considerations: Ground Contact
• The chassis is the common GND reference
- Do not have floating grounds
Signal GND/RTN
PCB GND 2
Monitor
PCB GND
PCB GND 1
Cable Shield
Shielding
11
Host
Chassis
Display
Chassis
Shielding
Ground Contact: Example
PCB 2
Signal &
GND (Return)
Cable Shield
PCB 1
Main Chassis
Shielding
12
PCB 3
Remote Chassis
360 Clamps
or Connector
Shells
Shielding
Summary
• Voltage regulator strongly recommended on
TX PVCC
• Damping resistors on all parallel data lines
- Improves signal integrity and EMI
• Solid ground plane
• Use chassis as common GND reference
13
Conclusion
• PanelLink is very robust, but is still a highspeed gigabit serial link
- Higher data rate than gigabit ethernet
• Reference schematics provided
• Silicon Image is the leader in experience
and knowledge of this technology
- Applications knowledge
- Local and factory support
- Production and testing
14