[SOLVED] Structural difference between buffer and higher drive strengh buffer of same height

[ramesh28]

Structural difference between buffer and higher drive strenght buffer of same height

Hello all,

As we come across standard cell library, we can find buffer of size 1X, 2X, 4X, 8X, 16X, and so on.. I know that drive strengh will be increases if we follow this order..
I observed that there is width difference between all of them.

Can anyone tell me what is stuctural difference between these buffer which having same height?


Thank you..

 

[erikl]

The difference is just the size of the output inverter.

 

[ramesh28]

Output inverter size means which parameters differs? at what proportion?

can you give detail idea?

 

[erikl]

Output inverter size means which parameters differs? at what proportion?

can you give detail idea?

The W/L ratio of both transistors. In the same proportion as the driver strength.

 

[ramesh28]

Thanx for reply erikl.

I just wanted to know as you tell difference between buffer and higher drive strength buffer is output inverter size. But if you consider any other standard cell like NAND, NOR, AND, XOR, etc in that case there may or may not output inverter then which is structural difference between them and higher drive strength cell.

 

[erikl]

It's always the output driver! In case of NAND & NOR, all 4 transistors are W/L-multiplied.

 

[ramesh28]

Thanx erikl..