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AR# 1634

Printed Circuit Board (PCB) considerations of Xilinx devices


Intelligent Printed Circuit Board layout may prevent future design problems like reflections, glitches, ground bounce/rise, crosstalk, and other system related problems in several high speed applications.

These are some suggestions for PCB layout that may help prevent these undesirable side-effects from happening.

Further information on minimizing Ground Bounce may be found in the 1996 Xilinx Data Book on pages 13-10 to 13-11 or on the Xilinx WWW site at :



1. PC-Boards should contain seperate Vcc and ground planes

connected directly to the device's supply pins.

2. Decouple each Vcc pin on the device with a low-inductance

decoupling capacitor of 0.01 to 0.1 uF very close to each

Vcc pin. For more information on decoupling capacitors

please refer to (Xilinx Solution 777).

3. Decouple the Printed Circuit Board power inputs with a

0.1 uF cearmic (high frequency) and 100 uF electrolytic

(low frequency) filter capacitors.

4. Use wide spacing between fast signal lines (particularly

clocks) to minimize crosstalk.

5. All device ground pins must be tied together.

6. Avoid using sockets to attach the device to the board.

Sockets usually provide a higher pin capacitance and

a poorer connection than if the device is soldered

to the board.

7. Connect clocks to input pins that are close to a ground


8. Locate the device as close as possible to the chip(s) it

drives and/or is driven by. This will minimze transmission

line effects.
AR# 1634
Date 04/05/2012
Status Archive
Type General Article