
3-18
27 x 27 Complex Multiplier
SV51004
2013.05.06
Figure 3-15: 18 x 25 Complex Multiplier with Three Variable Precision DSP Blocks for Stratix V Devices
Multiplier
b[24..0]
a[24..0]
d[17..0]
d[17..0]
25
25
18
18
Variable Precision DSP Block 1
x
x
Multiplier
Chainout
Adder
c[17..0]
b[24..0]
18
25
Variable Precision DSP Block 2
x
Multiplier
+
44
[(c + d) b + (a - b) d]
d[17..0]
18
Chainout
Adder
c[17..0]
a[24..0]
18
25
x
+
44
[(c - d) a + (a - b) d]
Variable Precision DSP Block 3
27 x 27 Complex Multiplier
Stratix V devices support an individual 27 x 27 complex multiplication mode. You require four variable
precision DSP blocks to implement an individual 27 x 27 complex multiplication mode.
You can implement the imaginary part [(a x d) + (b x c)] in the first and second variable precision DSP
blocks, and you can implement the real part [(a x c) - (b x d)] in the third and fourth variable precision DSP
blocks.
You can achieve the difference of two 27 x 27 multiplications by enabling the NEGATE control signal in the
fourth variable precision DSP block.
Altera Corporation
Variable Precision DSP Blocks in Stratix V Devices
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