XC2V4000 Datasheet, PDF (27/311 Pages) Xilinx, Inc – Summary of Features

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Virtex™-II Platform FPGAs: Detailed Description
Sum of Products
Each Virtex-II slice has a dedicated OR gate named ORCY,
ORing together outputs from the slices carryout and the ORCY
from an adjacent slice. The ORCY gate with the dedicated
Sum of Products (SOP) chain are designed for implementing
large, flexible SOP chains. One input of each ORCY is con-
nected through the fast SOP chain to the output of the previous
ORCY in the same slice row. The second input is connected to
the output of the top MUXCY in the same slice, as shown in
Figure 25.
LUTs and MUXCYs can implement large AND gates or
other combinatorial logic functions. Figure 26 illustrates
LUT and MUXCY resources configured as a 16-input AND
gate.
ORCY
ORCY
4 _LUT
4 _LUT
MUXCY
4 _LUT
Slice 1
MUXCY
4 _LUT
MUXCY
Slice 3
MUXCY
4 _LUT
4 _LUT
ORCY
MUXCY
4 _LUT
Slice 1
MUXCY
4 _LUT
ORCY
SOP
MUXCY
Slice 3
MUXCY
4 _LUT
4 _LUT
4
MUXCY
Slice 0
4
MUXCY
V_CC
LUT
LUT
MUXCY
Slice 2
MUXCY
V_CC
CLB
4 _LUT
4 _LUT
MUXCY
4 _LUT
Slice 0
MUXCY
4 _LUT
V_CC
Figure 25: Horizontal Cascade Chain
MUXCY
Slice 2
MUXCY
V_CC
CLB
ds031_64_110300
OUT
4
LUT
4
LUT
MUXCY
0
1
“0”
Slice
MUXCY
0
1
“0”
16
AND
OUT
4
LUT
4
LUT
MUXCY
0
1
“0”
Slice
MUXCY
0
1
VCC
DS031_41_110600
Figure 26: Wide-Input AND Gate (16 Inputs)
DS031-2 (v3.0) August 1, 2003
Product Specification
www.xilinx.com
1-800-255-7778
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