Fusion Family of Mixed Signal FPGAs
Revision 4 2-9
Routing Architecture
The routing structure of Fusion devices is designed to provide high performance through a flexible four-
level hierarchy of routing resources: ultra-fast local resources; efficient long-line resources; high-speed
very-long-line resources; and the high-performance VersaNet networks.
The ultra-fast local resources are dedicated lines that allow the output of each VersaTile to connect
directly to every input of the eight surrounding VersaTiles (Figure 2-8). The exception to this is that the
SET/CLR input of a VersaTile configured as a D-flip-flop is driven only by the VersaNet global network.
The efficient long-line resources provide routing for longer distances and higher-fanout connections.
These resources vary in length (spanning one, two, or four VersaTiles), run both vertically and
horizontally, and cover the entire Fusion device (Figure 2-9 on page 2-10). Each VersaTile can drive
signals onto the efficient long-line resources, which can access every input of every VersaTile. Active
buffers are inserted automatically by routing software to limit loading effects.
The high-speed very-long-line resources, which span the entire device with minimal delay, are used to
route very long or high-fanout nets: length ±12 VersaTiles in the vertical direction and length ±16 in the
horizontal direction from a given core VersaTile (Figure 2-10 on page 2-11). Very long lines in Fusion
devices, like those in ProASIC3 devices, have been enhanced. This provides a significant performance
boost for long-reach signals.
The high-performance VersaNet global networks are low-skew, high-fanout nets that are accessible from
external pins or from internal logic (Figure 2-11 on page 2-12). These nets are typically used to distribute
clocks, reset signals, and other high-fanout nets requiring minimum skew. The VersaNet networks are
implemented as clock trees, and signals can be introduced at any junction. These can be employed
hierarchically, with signals accessing every input on all VersaTiles.
Note: Input to the core cell for the D-flip-flop set and reset is only available via the VersaNet global network connection.
Figure 2-8 • Ultra-Fast Local Lines Connected to the Eight Nearest Neighbors
L
L
L
LL
L
Inputs
Output
Ultra-Fast Local Lines
(connects a VersaTile to the
adjacent VersaTile, I/O buffer,
or memory block)
L
LL
Long Lines
