EP4SE360F35I4 Datasheet, PDF (88/432 Pages) Altera Corporation – This section provides a complete overview of all features relating to the Stratix IV device family, which is the most architecturlly advanced

4–8
Chapter 4: DSP Blocks in Stratix IV Devices
Stratix IV Operational Modes Overview
Stratix IV Operational Modes Overview
You can use each Stratix IV DSP block in one of five basic operational modes.
Table 4–2 lists the five basic operational modes and the number of multipliers that you
can implement within a single DSP block, depending on the mode.
Table 4–2. Stratix IV DSP Block Operation Modes
Mode
Multiplier # of # per Signed or
in Width Mults Block Unsigned
RND,
SAT
In Shift
Register
Chainout
Adder
1st Stage
Add/Sub
2nd
Stage
Add/Acc
9 bits
1
8
Both
No
No
No
—
—
12 bits
1
6
Both
No
No
No
Independent
Multiplier
18 bits
1
4
Both
Yes
Yes
No
36 bits
1
2
Both
No
No
No
—
—
—
—
—
—
Double
1
2
Both
No
No
No
—
—
Two-Multiplier
Adder ⁽¹⁾
18 bits
2
4
Signed ⁽⁴⁾
Yes
No
No
Both
—
Four-Multiplier
Adder
18 bits
4
2
Both
Yes
Yes
Yes
Both Add Only
Multiply
Accumulate
18 bits
4
2
Both
Yes
Yes
Yes
Both
Both
Shift ⁽²⁾
36 bits ⁽³⁾
1
2
Both
No
No
—
—
—
High Precision
Multiplier Adder
1836
2
2
Both
No
No
No
— Add Only
Notes to Table 4–2:
(1) This mode also supports loopback mode. In loopback mode, the number of loopback multipliers per DSP block is two. You can use the
remaining multipliers in regular two-multiplier adder mode.
(2) Dynamic shift mode supports arithmetic shift left, arithmetic shift right, logical shift left, logical shift right, and rotation operation.
(3) Dynamic shift mode operates on a 32-bit input vector but the multiplier width is configured as 36 bits.
(4) Unsigned value is also supported but you must ensure that the result can be contained within 36 bits.
The DSP block consists of two identical halves (the top half and bottom half). Each
half has four 18 × 18 multipliers.
The Quartus^® II software includes megafunctions used to control the mode of
operation of the multipliers. After making the appropriate parameter settings using
the megafunction’s MegaWizard^ Plug-In Manager, the Quartus II software
automatically configures the DSP block.
Stratix IV DSP blocks can operate in different modes simultaneously. Each half block
is fully independent except for the sharing of the three clock, ena, and aclr signals.
For example, you can break down a single DSP block to operate a 9 × 9 multiplier in
one half block and an 18 × 18 two-multiplier adder in the other half block. This
increases DSP block resource efficiency and allows you to implement more
multipliers within a Stratix IV device. The Quartus II software automatically places
multipliers that can share the same DSP block resources within the same block.
Stratix IV Device Handbook
Volume 1
February 2011 Altera Corporation