To use adder and multiplier of DSP48 in V4

Apr 11, 2006 3 Replies

Hi all, Is it possible to use the adder and multiplier in the DSP48 block of the virtex4 FPGA separately but simultaniously. From the user guide i get a feeling "No" but i wanted to know your expert openion on this issue. Thanks and regards Sumesh V S



No

;p

The adder is also there to add the two partial products of the multiplier so ... And indeed in the manual it's quite clear there is no way ...

No, in fact the adder is always used with the multiplier. The adder is actually a tree adder that combines the multiplier partial products and an additional term from the C input. It is still used to combine multiplier partial products even if you don't use the C input (not using it forces a 0 into that input of the adder tree.

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