FreePDK45:LVS

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  • Introduction

Layout vs Schematic verification (LVS) ensures that the connectivity of the physical design (the layout) matches with the logical design represented by the schematic or netlist. The inputs to Calibre LVS are an SVRF rule file, a layout netlist or database, and a source netlist or database. The LVS outputs that always occur include a run transcript and an LVS Report. A set of other results can also be generated.

  • Setup

Calibre LVS can be executed at command line as well as in a interactive mode. The interactive mode is easy to use and is explained below.

To use Calibre LVS, you need to follow the additional steps than one mentioned at Developer's Getting Started Guide .At the "Start Cadence Virtuoso" step you need to set the varaible MGC_HOME as follows

setenv MGC_HOME /afs/bp.ncsu.edu/dist/calibre20061/ 

and then setup the environment and start Cadence Virtuoso and Calibre integrated with in it, using the following commands

add calibre
myadd myfp
myadd icoa
icfb & 

In the CIW window, you should be able to see "Calibre Skill Interface" and some copyright information and that means the Calibre is loaded properly.

  • To run LVS

Open the layout you want to run LVS in Virtuoso Layout Editor.You should be able to see a menu option called Calibre Let the name of your layout be my_layout

Setup the layer map file which will be used while streaming the layout to GDII format. Goto Calibre-> Setup-> Layout Export and in the Layer Map File type in the location of the layer map file and select Show dialog before export (This is done so that every time you run LVS, this dialogue box opens and you can make sure that correct Layer Map file is being selected, otherwise LVS wont work correctly)

Next, goto Calibre -> Run LVS

Calibre Interactive - LVS window pops up

You get an option for specifying a Runset File Runset file is a file which has details about the various settings you need to specify and if you want a specific set of defaults, it can be saved in a runset file and loaded the next time you start off Calibre Interactive and saves you the trouble of specifying all the settings once again. The runset file will be saved in the directory you started ICFB, have a look at it.

Rules

Calibre -LVS Rules File - select the Calibre Rules file from the path Calibre - LVS Run Directory - select the directory from where you started ICFB

Inputs

select Hierarchial, Layout vs Netlist In the Layout tab Files : my_layout.calibre.gds Top Cell: my_layout Layout Netlist: my_layout.sp These options are already be filled in by the tool, leave them as it is Format: select GDSII and select the option "Export from layout viewer" (This is very important)

In the Netlist tab Files: my_layout.src.net Top Cell:my_layout These options are already be filled in by the tool, leave them as it is Format: select SPICE and select the option "Export from schematic viewer" (This is very important)

Outputs

Under the Report/SVDB

LVS Report File: my_layout.lvs.report svdb directory: svdb These options are already be filled in by the tool, leave it as it is Select View Report after LVS Finishes

Under SVDB database select "Create SVDB Database" and "Start RVE after LVS finshes"

Dont make any changes to Run Control

Then press Run LVS

Once LVS is completed, LVS report is opened automatically and RVE is also started.