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ProASIC3/E Flash Family FPGAs
2- 14
v2.1
Clock Aggregation
Clock aggregation allows for multi-spine clock domains.
A MUX tree provides the necessary flexibility to allow
long lines or I/Os to access domains of one, two, or four
global spines. Signal access to the clock aggregation
system is achieved through long-line resources in the
central rib, and also through local resources in the north
and south ribs, allowing I/Os to feed directly into the
clock system. As
Figure 2-13 indicates, this access system
is contiguous.
There is no break in the middle of the chip for the north
and south I/O VersaNet access. This is different from the
quadrant clocks located in these ribs, which only reach
Figure 2-12 Spine Selection MUX of Global Tree
Figure 2-13 Clock Aggregation Tree Architecture
Internal/External
Signal
Internal/External
Signal
Internal/External
Signals
Spine
Global Rib
Global Driver MUX
Tree Node MUX
Internal/External
Signals
Tree Node MUX
Global Spine
Global Rib
Global Driver and MUX
I/O Access
Internal Signal Access
I/O Tiles
Global Signal Access
Tree Node MUX