Need help regarding LEF and LIB files

[pavan.mk]

Hello everyone,

This post is regarding .lib and lef files. I wanted to know exactly what these files contain.
According to my knowledge in LEF we have - Tech LEF, Cell LEF and Macro LEF. I don't know what each of them contain.
In a .lib file, we the operating conditions(PVT info), cell information (like its area, power, functionality, pin direction).
If anyone could give me some more information regarding this, it would be of great help.


Thanks,
Pavan

 

[rca]

LEF contains a simpliest view (pin placement, blockage, antenna) of the std-cell & Macro to be not-overload the PR tool. The techno LEF contains the technology rule for PR tool.
LIB contains the power & timing views.

 

[Prashanthanilm]

LEF is the extraction of Layout . It gives you the orientation, pin position and each and everything of Layout.

LIB file constist of timing views and also power.

.lib file is generated by characterization of Standard cells. Characterization means operation of cells in different load and slew.

LEF contains a simpliest view (pin placement, blockage, antenna) of the std-cell & Macro to be not-overload the PR tool. The techno LEF contains the technology rule for PR tool.
LIB contains the power & timing views.

Whether the .lib file is Technology dependant?.

What is the format of .lib file?

 

[rca]

the .lib is the liberty format, from Synopsys, we could say it is techonology dependant because, it describe the power and timing information of macro or std cell, the relative to a specific process-corner.

 

[karukaka]

.lib file is technology dependent. as far as synopsys 90nm is considered it consists of saed90nm_max,saed90nm_min,saed90nm_typ libraries.all these libraries consists of many parameters such as PVT conditions,timing related issues like slew etc..and also it consists of leakage power etc.... by using all these standard values we are going to constraint our design ,depending upon which technology library we are using either 90nm,45,32 or 22nm.

 

[Prashanthanilm]

Karukaka,

Whether .lib file is created by Vendors or any body is capable of doing it?.

How is the format of .lib files look like?

what is the relationship between LEF and LIB?

 

[vidyacharan]

Hi,

In order to perform an ASIC physical design you need both Physical libs and logical libs of the standard cells and macros.

From your question, LEF constitutes physical part and .lib constitute logical part.

1. LEF : Library Exchange Format


CELL LEF : contains the physical description like pin shapes, obstruction (blockages) etc of the standard cell.

TECHNOLOGY LEF : Contains the technology information like layers, layer widths, spacing rules, unit R and C values etc.

2. .lib contains the logical information like timing arcs and power information of the standard cell.

In general, foundries and IP vendors provide both the LEF and .lib files.