Honored Contributor
Honored ContributorWhat you say is correct. If all the multipliers were the same size then they would all be converted to logic at the same time. So you would increase the threshold by 1 and go from 50 DSPs to 0. The threshold becomes a far more useful features if you have many multipliers of different sizes in your design.
I suspect your actual problem is down to a limitation of the tool. It will only try to convert multipliers if it hasn't already determined to combine them into an alt_multadd. If you are using DSPBA to create FIRs, you might be creating the filters in non-constant mode. This could perhaps prevent multipliers from being converted to shifted adder trees which could save you a few multipliers.
