Hello everybody, I'm interested in the implementation of a 32x32 bit multiplier (unsigned values). The target FPGA is Virtex V300e I would like to implement a system that is not too big, while I have not a lot of timing constraints. Using a behavioral approach I obtain a multiplier that needs about 17% of the FPGA, I would like to reduce this size and the target frequency is about 70Mhz. Where can I find some good manual that can help me in this task? can you give me some advice about how to code this device? Any help will be appreciated.
Hints for efficient 32 bit multiplier
Sep 22, 2005
4 Replies
Suppose you want to calculate p * q. If p = a * 2^16 + b and q = c * 2^16 + d then p * q = (a*c * 2^32 + (a*d+b*c) * 2^16 + b * d) which says that you can use 4 16 bit multipliers to do a 32 bit multiplication or use one
16 bit multiplier and run it over 4 cycles to get what you want.
Using karatsuba, you might get away with only 3 multipliers and just a few extralogic.
Sylvain
Do you need a result on every cycle of the 70 MHz clock? If not, then you can do the multiplication over several clock cycles summing the partial products in an accumulator. Look at the multipliers page on my website (Under the DSP section) for some guidance on different multipliers.
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
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Thanks a lot, I will read it. Thanks to everyone Gio
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