EP2SGX60CF780C4N Datasheet, PDF (93/316 Pages) Altera Corporation – Support for numerous single-ended and differential I/O standards

Stratix II GX Architecture
Modes of Operation
The adder, subtractor, and accumulate functions of a DSP block have four
modes of operation:
■ Simple multiplier
■ Multiply-accumulator
■ Two-multipliers adder
■ Four-multipliers adder
Table 2–22 shows the different number of multipliers possible in each
DSP block mode according to size. These modes allow the DSP blocks to
implement numerous applications for DSP including FFTs, complex FIR,
FIR, 2D FIR filters, equalizers, IIR, correlators, matrix multiplication, and
many other functions. The DSP blocks also support mixed modes and
mixed multiplier sizes in the same block. For example, half of one DSP
block can implement one 18 × 18-bit multiplier in multiply-accumulator
mode, while the other half of the DSP block implements four 9 × 9-bit
multipliers in simple multiplier mode.
Table 2–22. Multiplier Size and Configurations per DSP Block
DSP Block Mode
Multiplier
Multiply-accumulator
Two-multipliers adder
Four-multipliers adder
9×9
18 × 18
36 × 36
Eight multipliers with Four multipliers with four
eight product outputs
product outputs
—
Two 52-bit multiply-
accumulate blocks
Four two-multiplier adder Two two-multiplier adder
(two 9 × 9 complex
(one 18 × 18 complex
multiply)
multiply)
Two four-multiplier adder One four-multiplier adder
One multiplier with one
product output
—
—
—
DSP Block Interface
The Stratix II GX device DSP block input registers can generate a shift
register that can cascade down in the same DSP block column. Dedicated
connections between DSP blocks provide fast connections between the
shift register inputs to cascade the shift register chains. You can cascade
registers within multiple DSP blocks for 9 × 9- or 18 × 18-bit FIR filters
larger than four taps, with additional adder stages implemented in
ALMs. If the DSP block is configured as 36 × 36 bits, the adder, subtractor,
or accumulator stages are implemented in ALMs. Each DSP block can
route the shift register chain out of the block to cascade multiple columns
of DSP blocks.
Altera Corporation
October 2007
2–85
Stratix II GX Device Handbook, Volume 1