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Accelerator Series FPGAs – ACT 3 Family
Architecture
This section of the data sheet is meant to familiarize the user
with the architecture of the ACT 3 family of FPGA devices. A
generic description of the family will be presented first,
followed by a detailed description of the logic blocks, the
routing structure, the antifuses, and the special function
circuits. The on-chip circuitry required to program the
devices is not covered.
Topology
The ACT 3 family architecture is composed of six key
elements: Logic modules, I/O modules, I/O Pad Drivers,
Routing Tracks, Clock Networks, and Programming and Test
Circuits. The basic structure is similar for all devices in the
family, differing only in the number of rows, columns, and
I/Os. The array itself consists of alternating rows of modules
and channels. The logic modules and channels are in the
center of the array; the I/O modules are located along the
array periphery. A simplified floor plan is depicted in
Logic Modules
ACT 3 logic modules are enhanced versions of the 1200XL
family logic modules. As in the 1200XL family, there are two
types of modules: C-modules and S-modules. The C-module is
functionally equivalent to the 1200XL C-module and
implements high fanin combinatorial macros, such as 5-input
AND, 5-input OR, and so on. It is available for use as the CM8
hard macro. The S-module is designed to implement
high-speed sequential functions within a single module.
S-modules consist of a full C-module driving a flip-flop, which
allows an additional level of logic to be implemented without
additional propagation delay. It is available for use as the
DFM8A/B and DLM8A/B hard macros. C-modules and
S-modules are arranged in pairs called module-pairs.
Module-pairs are arranged in alternating patterns and make
up the bulk of the array. This arrangement allows the
placement software to support two-module macros of four
types (CC, CS, SC, and SS). The C-module implements the
following function:
Y = !S1 * !S0 * D00 + !S1 * S0 * D01 + S1 * !S0 * D10 + S1 * S0
* D11
where: S0 = A0 * B0 and S1 = A1 + B1
Figure 1 Generalized Floor Plan of ACT 3 Device
IO
C
S
C
S
IO
C
S
C
S
IO
C
S
C
S
IO
C
BIO IO
IO
BIN S
C
S
IO
BIN S
C
S
IO
BIN S
C
S
IO
CLKM
IO
BIN S
C
IO
C
S
C
S
C
S
IO
C
An Array with
n rows and m columns
Top I/Os
Bottom I/Os
Left I/Os
Right I/Os
Rows
n+1
n
n–1
2
1
0
Channels
n+1
n
n–1
2
1
0
n+2
0
1
2
3
4
5
c–1
c
c+1
m m+1 m+2 m+3
Columns