Considerations for Multiplier Design

[confused soul]

I am trying to build a 16 X 16 bit multiplier using Mentor Graphics. In
the design of this multiplier, for the adder blocks should I go for a
16 bit adders or should it be 8 bit or 4 bit. I am not sure on how to
choose the optimal number of bits for the adder to be used in this
multiplier. Any pointers to this will be helpful.

 

[tlbs]

Here are several different options:

http://www.andraka.com/multipli.htm

A few years ago I made a 12 x 12 using the Carry Save Array method. It
can easily be expanded to 16 bits.

 

[Ken Smith]

I am trying to build a 16 X 16 bit multiplier using Mentor Graphics. In
the design of this multiplier, for the adder blocks should I go for a
16 bit adders or should it be 8 bit or 4 bit. I am not sure on how to
choose the optimal number of bits for the adder to be used in this
multiplier. Any pointers to this will be helpful.

How fast do you need the results from the multiply?

If you have all day, a 1 bit adder and shift register design uses about
the least silicon.

 

[Bob Eldred]

I am trying to build a 16 X 16 bit multiplier using Mentor Graphics. In
the design of this multiplier, for the adder blocks should I go for a
16 bit adders or should it be 8 bit or 4 bit. I am not sure on how to
choose the optimal number of bits for the adder to be used in this
multiplier. Any pointers to this will be helpful.

A 16 bit multiplier should have a 32 bit accumulator if all of the possible
bits of precision are considered. How fast does this have to run? Many DSP
processors and some micro- controllers have multiply instructions and can do
a it a one clock cycle. If speed is not an issue, you can do it in any
processor even a PIC with a software multiply. I takes several hundred
steps but that may be fast enough for many applications. If it were me, I'd
look for a single chip solution probably using a microprocessor if speed is
not important or a DSP chip if it is.
Bob

 

[confused soul]

The carry save blocks were 4 bits, 8 bits or 12 bits?

 

[confused soul]

i am looking for speed in the range of 45-60 ns for clocked multiply
time

 

[Robert Baer]

The carry save blocks were 4 bits, 8 bits or 12 bits?

Use a QSM.