Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How are LEF, DEF, QRC Techfile and Capacitance table file related to each other?

Status
Not open for further replies.
T

ttxs

Junior Member level 1
Joined
Jun 26, 2013
Messages
16
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
249
I am new to this field and I don't have a good understanding of the flow.
Could anybody help me to understand LEF, DEF, QRC Techfile and Capacitance table files?

My current understanding is that:

(1) LEF has "cell level" information, while DEF has "floorplan level" information. In this sense, I guess DEF is a higher level description of a design than LEF.
(2) QRC tech file, I am not quite sure what it is, and I guess it is like LEF, which is on a lower level than DEF... I am not sure what Capacitance table file is at all.

The main reason why I want to learn about the above relations is that, I came across two concepts: "pre-route extraction" and "rc-grid density computing", which seem to have a lot to do with LEF, DEF, QRC techfile and Capacitance table files.

My current understanding is that:
(1) techfile extraction (SoC Encounter will generate patterns.out log file) deals with LEF and QRC techfiles. It is a low level extraction.
(2) rc-grid-density computing (by Encounter command "peGetGridCorrelationData") deals with DEF and floorplan. It is a high level extraction.
I don't know why there is a keyword "grid". But I guess "pre-route extraction" is made of the above two operations.

Is the above understanding correct? I have a lot of separate pieces, but I can never put them together for a complete story :-(
 

ttxs said:
I am new to this field and I don't have a good understanding of the flow.
Could anybody help me to understand LEF, DEF, QRC Techfile and Capacitance table files?

My current understanding is that:

(1) LEF has "cell level" information, while DEF has "floorplan level" information. In this sense, I guess DEF is a higher level description of a design than LEF.
(2) QRC tech file, I am not quite sure what it is, and I guess it is like LEF, which is on a lower level than DEF... I am not sure what Capacitance table file is at all.

The main reason why I want to learn about the above relations is that, I came across two concepts: "pre-route extraction" and "rc-grid density computing", which seem to have a lot to do with LEF, DEF, QRC techfile and Capacitance table files.

My current understanding is that:
(1) techfile extraction (SoC Encounter will generate patterns.out log file) deals with LEF and QRC techfiles. It is a low level extraction.
(2) rc-grid-density computing (by Encounter command "peGetGridCorrelationData") deals with DEF and floorplan. It is a high level extraction.
I don't know why there is a keyword "grid". But I guess "pre-route extraction" is made of the above two operations.

Is the above understanding correct? I have a lot of separate pieces, but I can never put them together for a complete story :-(
Click to expand...

this sounds like guesswork. almost entirely wrong.

LEF is used to import IP layout information into the physical synthesis tool, ie., encounter. it is a simplified version of the layout of the IP.
DEF can be used for saving a floorplan, and it can instantiate cells from a LEF file. however, DEF is not the default format for floorplan within encounter. there is a .fplan format.
QRCtechfile and captables are essentially the same. for newer techs you should only use QRC files as the accuracy is much better. both files are used to estimate capacitance values of your metal lines, which will impact timing for sure. extraction is the process of calculating such capacitance values.

techfile extraction is a completely different matter. I think you are using the wrong term. maybe you are referring to extraction using LEF file information only. I don't know.
rc-grid-density computation is a term that no designer will ever use. it's probably internal to encounter and you should not worry about it. extraction has nothing to do with what you report here. extraction is done by running extractRC command.
 
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top