Digital Signal Processing Block
The most commonly used DSP functions are finite impulse response (FIR)
Digital Signal
Processing
Block
filters, complex FIR filters, infinite impulse response (IIR) filters, fast
Fourier transform (FFT) functions, direct cosine transform (DCT)
functions, and correlators. All of these blocks have the same fundamental
building block: the multiplier. Additionally, some applications need
specialized operations such as multiply-add and multiply-accumulate
operations. Stratix devices provide DSP blocks to meet the arithmetic
requirements of these functions.
Each Stratix device has two columns of DSP blocks to efficiently
implement DSP functions faster than LE-based implementations. Larger
Stratix devices have more DSP blocks per column (see Table 2–13). Each
DSP block can be configured to support up to:
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Eight 9 × 9-bit multipliers
Four 18 × 18-bit multipliers
One 36 × 36-bit multiplier
As indicated, the Stratix DSP block can support one 36 × 36-bit multiplier
in a single DSP block. This is true for any matched sign multiplications
(either unsigned by unsigned or signed by signed), but the capabilities for
dynamic and mixed sign multiplications are handled differently. The
following list provides the largest functions that can fit into a single DSP
block.
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36 × 36-bit unsigned by unsigned multiplication
36 × 36-bit signed by signed multiplication
35 × 36-bit unsigned by signed multiplication
36 × 35-bit signed by unsigned multiplication
36 × 35-bit signed by dynamic sign multiplication
35 × 36-bit dynamic sign by signed multiplication
35 × 36-bit unsigned by dynamic sign multiplication
36 × 35-bit dynamic sign by unsigned multiplication
35 × 35-bit dynamic sign multiplication when the sign controls for
each operand are different
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36 × 36-bit dynamic sign multiplication when the same sign control
is used for both operands
1
This list only shows functions that can fit into a single DSP block.
Multiple DSP blocks can support larger multiplication
functions.
Figure 2–29 shows one of the columns with surrounding LAB rows.
2–52
Altera Corporation
July 2005
Stratix Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
