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-   -   To use adder and multiplier of DSP48 in V4 (http://www.fpgacentral.com/group/showthread.php?t=58310)

vssumesh 04-11-2006 07:59 AM

To use adder and multiplier of DSP48 in V4
 
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


Sylvain Munaut 04-11-2006 10:31 AM

Re: To use adder and multiplier of DSP48 in V4
 
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 ...


Ray Andraka 04-12-2006 04:46 PM

Re: To use adder and multiplier of DSP48 in V4
 
vssumesh wrote:
> 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, 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.

vssumesh 04-13-2006 08:26 AM

Re: To use adder and multiplier of DSP48 in V4
 
Thanks Andraka and Munaut...



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