cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
christine1225
Adventurer
Adventurer
789 Views
Registered: ‎07-10-2015

how to use dsp48 to calculate the sum of 3 22 signed bit input ?

how to use dsp48 to calculate the sum of 3 22 signed bit input ? 

 

A + B + C。And how many clocks it takes?

0 Kudos
1 Reply
avrumw
Expert
Expert
737 Views
Registered: ‎01-23-2009

You could probably use the A+D pre-adder to do one addition, and the final adder to do the second. You would have to set the B input to 1 to generate (A+D)*1 + C. All these inputs are bigger than 22 bits.

 

This can be done in one clock, but will have a maximum frequency probably around the 300MHz range. If you can pipeline it, it would be able to go faster.

 

That being said, you can also do this operation in the fabric, just by using A+B+C - it will not be much slower (addition using the fabric carry chain is pretty fast).

 

Avrum

0 Kudos