5–24
Altera Corporation
Stratix II Device Handbook, Volume 2
January 2008
Differential Pin Placement Guidelines
Using Corner and Center Fast PLLs
■
If a differential bank is being driven by two fast PLLs, where the
corner PLL is driving one group and the center fast PLL is driving
another group, there must be at least 1 row of separation between the
two groups of DPA channels (see
Figure 5–22). The two groups can
operate at independent frequencies. Not all the channels are bonded
out of the die. Each LAB row is considered a channel, whether or not
it has I/O support.
■
No separation is necessary if a single fast PLL is driving DPA
channels as well as non-DPA channels as long as the DPA channels
are contiguous.
Figure 5–22. Usage of Corner and Center Fast PLLs Driving DPA Channels in a
Single Bank
Ref CLK
Diff I/O
Fast PLL
Ref Clk
Center PLL
Unused
One Unused
Channel for Buffer
Corner PLL
Used for DPA
Ref Clk
Channels Driven
by Center PLL
Channels Driven
by Corner PLL
