Logic Array Blocks
Each LAB consists of 10 LEs, LE carry chains, LAB control signals, a local
interconnect, look-up table (LUT) chain, and register chain connection
lines. The local interconnect transfers signals between LEs in the same
LAB. LUT chain connections transfer the output of one LE's LUT to the
adjacent LE for fast sequential LUT connections within the same LAB.
Register chain connections transfer the output of one LE's register to the
adjacent LE's register within an LAB. The Quartus® II Compiler places
associated logic within an LAB or adjacent LABs, allowing the use of
local, LUT chain, and register chain connections for performance and area
efficiency. Figure 2–2 details the Cyclone LAB.
Logic Array
Blocks
Figure 2–2. Cyclone LAB Structure
Row Interconnect
Column Interconnect
Direct link
interconnect from
adjacent block
Direct link
interconnect from
adjacent block
Direct link
Direct link
interconnect to
adjacent block
interconnect to
adjacent block
LAB
Local Interconnect
LAB Interconnects
The LAB local interconnect can drive LEs within the same LAB. The LAB
local interconnect is driven by column and row interconnects and LE
outputs within the same LAB. Neighboring LABs, PLLs, and M4K RAM
blocks from the left and right can also drive an LAB's local interconnect
through the direct link connection. The direct link connection feature
minimizes the use of row and column interconnects, providing higher
Altera Corporation
January 2007
2–3
Preliminary
ALTERA [ ALTERA CORPORATION ]
