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[SOLVED] Combining multipliers to make larger multiplier

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Wallboy

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I'm trying to create a 32x32 Unsigned Multiplier using smaller multipliers such as using 16x16 multipliers. My gut feeling is I need to use adders and shifters somewhere, but I just can't figure out how to do it. Any help would be appreciated, thanks.
 

Wallboy

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I seen your post in another thread and did it on paper, but it seems I would need a multiplier for each bit. I want something like two 16x16 multipliers to eventually get to a 32x32 result.
 

FvM

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ac + ad + bc + bd suggests four 16x16 multipliers needed, isn't it?
 

Wallboy

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Alright I think I'm starting to understand, I just need to figure out the shifts and partial add spots.
 

tariq786

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FVM dude

what is (a+b) (c+d) here?

Are they upper and lower 16 bits of the multiplicand and the multiplier?
 

Wallboy

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Alright, figured it out. Just needed four 16x16 multipliers and five 16x16 adders. No shifters were necessary.
 

tariq786

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wallboy dude

please share the schematic with all of us here so that we also learn and reinforce concepts

thanks
 

Wallboy

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Sure, I drew up a quick schematic that should work to build a 2Nx2N multiplier using four NxN multipliers.

multiplier.png
 
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