# how to use DesignWare cells?

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#### quan228228

##### Full Member level 4
In my design, there are 2 places using DW02_mult. DW02_mult is multiplier of DesignWare. The synthesis result is that the area of these two DW02_mult cell is different.

I want to know why the areas is different. how does Design Compiler select the cell from DesignWare. Or Can i designate which cell to be used?

Thanks!

#### waynejwd

##### Newbie level 3
U just need to do 2 steps. 1st, include the designware lib when do lib setup. 2nd, instantiate the designware directly, just as "DW02_mult Inst_DW02_mult (ports)".

Best rgds,
Wayne

#### avimit

##### Banned
The area may be differnet, because each instantiation of the mult may lie under different set of constraints. Say for example, one lies in the critical path, then synopsys will optimize it for timing, increasing its area, while the other if we assume, is in a relaxed timing path, will be optimized for area by synopsys. So each instance of the same DW component can have different area.
Synopsys selects DW components, mostly when you use operators, or when you explicitly instantiate in your design.
you can also hand instantiate them in your design. They are usually found in
$SYNOPSYS/dw Hope it helps, kr, Avi http://www.vlsiip.com njr@1 ### quan228228 Points: 2 Helpful Answer Positive Rating ### njr@1 Points: 2 Helpful Answer Positive Rating #### quan228228 ##### Full Member level 4 avimit said: The area may be differnet, because each instantiation of the mult may lie under different set of constraints. Say for example, one lies in the critical path, then synopsys will optimize it for timing, increasing its area, while the other if we assume, is in a relaxed timing path, will be optimized for area by synopsys. So each instance of the same DW component can have different area. Synopsys selects DW components, mostly when you use operators, or when you explicitly instantiate in your design. you can also hand instantiate them in your design. They are usually found in$SYNOPSYS/dw
Hope it helps,
kr,
Avi
http://www.vlsiip.com

yeh, you are right. These two places have different timing and driving capacity, so lead to different areas. I enhance the driving capacity by command "set load", the two area are almost equal.

thanks!

david

#### ivlsi

What's purpose of using the DesignWare modules? When their usage is recommended? When is not recommended? Thank you!

#### ivlsi

Isn't the DesignWare a cell (even complex, but still cell)? Is this a soft macro?

How fabs deal with DesignWare? It seems DesignWare's are not included in the STD libraries... Do fabs prepare special libraries for DesignWare's from Synopsys?

Do Cadence tools have the similar elements like DesignWare? How are they named there?

What's purpose of the DesignWare? Why are they needed?

Thank you!

#### englishdogg

##### Full Member level 5
DesignWare - i would say more better known as components rather cell.
These are technology inependent and best optimized code for a specific implementation for e.g DW_mult most commonly used that i have seen

It is a multiplier overall and these are not foundry specific and hence not in the library but with the tool installation
Cadence have similar known as ChipWare Components

As i said purpose is to use the most optimized code for the a specific datapath implementation.

#### ivlsi

DesignWare ... not in the library but with the tool installation
So, is it implemented using standard cells (STD Cells) of the vendor/fab/foundry?
Some our vendor asked not to use DesignWare's because they did not prepared such cells in their libs...

#### englishdogg

##### Full Member level 5
Using standard cells - yes
I would say that is strange since these are technology independent - di dyou witness any issues which you were using the product of this so called vendor

Probabaly they may have a different flow

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