Board Layout
Figure 7–16. VCCINT Plane Partitioned for VCCA Island
Thick VCCA Trace
Because of board constraints, you may not be able to partition a VCCA
island. Instead, run a thick trace from the power supply to each VCCA
pin. The traces should be at least 20 mils thick.
In each of these three cases, you should filter each VCCA pin with a
decoupling circuit shown in Figure 7–17. Place a ferrite bead that exhibits
high impedance at frequencies of 50 MHz or higher and a 10 µF tantalum
parallel capacitor where the power enters the board. Decouple each
VCCA pin with a 0.1 µF and 0.001 µF parallel combination of ceramic
capacitors located as close as possible to the Cyclone II device. You can
connect the GNDA pins directly to the same ground plane as the device’s
digital ground.
7–32
Cyclone II Device Handbook, Volume 1
Altera Corporation
February 2007
ALTERA [ ALTERA CORPORATION ]
