APEX 20KC Programmable Logic Device Data Sheet
Figure 3. LAB Structure
Row
Interconnect
MegaLAB Interconnect
LEs drive local,
MegaLAB, row,
and column
interconnects.
To/From
To/From
Adjacent LAB,
ESB, or IOEs
Adjacent LAB,
ESB, or IOEs
Column
Interconnect
Local Interconnect
The 10 LEs in the LAB are driven by
two local interconnect areas. These LEs
can drive two local interconnect areas.
Each LAB contains dedicated logic for driving control signals to its LEs
and ESBs. The control signals include clock, clock enable, asynchronous
clear, asynchronous preset, asynchronous load, synchronous clear, and
synchronous load signals. A maximum of six control signals can be used
at a time. Although synchronous load and clear signals are generally used
when implementing counters, they can also be used with other functions.
Each LAB can use two clocks and two clock enable signals. Each LAB’s
clock and clock enable signals are linked (e.g., any LE in a particular LAB
using CLK1will also use CLKENA1). LEs with the same clock but different
clock enable signals either use both clock signals in one LAB or are placed
into separate LABs.
If both the rising and falling edges of a clock are used in a LAB, both LAB-
wide clock signals are used.
10
Altera Corporation
ALTERA [ ALTERA CORPORATION ]
