Chapter 1: Overview for Cyclone V Device Family
1–13
Variable-Precision DSP Block
Variable-Precision DSP Block
Cyclone V devices feature a variable-precision DSP block that you can configure to
support signal processing with precisions ranging from 9 x 9, 18 x 19, and 27 x 27 bits
natively.
You can configure each DSP block during compilation as independent three 9 x 9, two
18 x 19, or one 27 x 27 multipliers. With a dedicated 64-bit cascade bus, you can
cascade multiple variable-precision DSP blocks to implement even higher precision
DSP functions efficiently.
The variable-precision DSP block also supports these features:
■
■
■
■
■
■
A 64-bit accumulator that is the largest in the industry.
A hard preadder that is available in both 18- and 27-bit modes.
Cascaded output adders for efficient systolic finite impulse response (FIR) filters.
Internal coefficient register banks, 8 deep, for each multiplier in 18- or 27-bit mode.
Fully independent multiplier operation.
A second accumulator feedback register to accommodate complex
multiply-accumulate functions.
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■
Efficient support for single- and double-precision floating point arithmetic.
The inferability of all modes by the Quartus® II design software.
Table 1–11 lists the relevant DSP block configurations for a few usage examples.
Table 1–11. Variable-Precision DSP Block Configurations for Cyclone V Devices
Usage Multiplier Size (Bit)
Low precision fixed point for video applications Three 9 x 9
Two 18 x 19
DSP Block Resource
1 variable-precision DSP block
1 variable-precision DSP block
Medium precision fixed point in FIR filters
FIR filters and general DSP usage
Two 18 x 19 with accumulate 1 variable-precision DSP block
High precision fixed- or floating-point implementations One 27 x 27 with accumulate 1 variable-precision DSP block
Table 1–12 lists the variable-precision DSP resources by bit precision for each
Cyclone V device.
Table 1–12. Number of Multipliers in Cyclone V Devices (Part 1 of 2)
Independent Input and Output
Multiplications Operator
18 x 18
Multiplier
Adder
Summed
with 36-bit
Input
Variable-
precision
DSP Block
18 x 19
Multiplier
Adder Mode
Variant
Device
9 x 9
18 x 19
Multiplier
27 x 27
Multiplier
Multiplier
5CEA2
5CEA4
5CEA5
5CEA7
5CEA9
25
72
75
216
50
25
72
25
72
25
72
144
248
312
684
Cyclone V E
124
156
342
372
124
156
342
124
156
342
124
156
342
468
1,026
February 2012 Altera Corporation
Cyclone V Device Handbook
Volume 1: Device Overview and Datasheet
ALTERA [ ALTERA CORPORATION ]
