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Ask for help on the corner analysis

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Advanced Member level 4
Apr 27, 2005
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Dear Fellows,

I am new to Cadence Analog Environment, and I am using TSMC18RF. I am done with my preliminary simulation. Now I want to simulate the corner analysis with Vt. However, I don't know where I should start it. I can only find the "Corners..." in the TOOLS menu, but I don't know how to fill it. I tried to search if there is a tutorial available, no luck. Could someone be nice to show me how to do it step by step? Or point me a good tutorial? My library is auto filled in the SETUP --model library menu, therefore I can't do anything there. And I can't find the Hit-Kit Utilities in the main CIW as a tutorial talked.

Thank you very much for your great help in advance.


I know it is not what you need - but I always use the model statement (can you use ocean run?)

I got the required corners model - use the ocean run (it is a SKILL lang. to run the core cadance) a "model" statement and set to corner, and simulate.

Thank you, Shutter_Man. I don't know anything about Ocean. I would like to learn, but it takes time. I want to start a quick corner analysis.



Actually you do not have to know ocean to use it....
Under the host - simply run : ocean

than - you get the ">" signal confirming you are under ocean.

Now - back to analog-artist - in the file just use the Sesion->Save_script
give a proper name with .ocn for convinience.

This file is actualy a ocean script. now - open it - and you have acess to the MODEL to replace to the correct library of your choosing (I am working with a different set - proprietary -not the TSMC ).

in the ocean - just type: >load("file name") this will run the file.

To view the result use the : Tools-Result_browser

Hope you nail this,

Thank you, Shutter_man, I am going to try what you suggested.

I also had a problem. I included the native_18.scs model in my corner analysis with the sigle model lib setup, and I used "ff_na, fs_na, etc", then it told me other nmos and pmos are not defined. If I used mm018_scs, and tested the "ff, fs, etc" corners, then it told me the native nmos is not defined. How could I include the model file to define all kinds of nmos and pmos?



I havent worked on TSMC foundry but some other foundries give a fet.scs file or a model.scs file that links the .scs files for all fet, res, cap etc. Do you have any such file? If so try using it.

Hello Maddy,

I have mm_018.scs, it includes everything, I think. However, when I use ff, it can't recognize the native fet; or if I use ff_na, then the normal fet is not recognized. Any idea?


in extreme temperature/process/temperature you can find corners
Hi Binjiang

I have faced similar problems in other foundry (UMC). I could resolve them by reading the documents that come with the Process Design Kit. Thats the easiest way out because each PDK organizes its model files differently.

Sorry couldnt give a direct answer...


There is a very good tool in Cadence for corner analysis called Aptivia (or sometimes Vsde stand for virtuoso specification driven environment). Check if you have this tool integrated you setup, CIW->Tools->Aptivia. By the way, Aptivia uses Skill language at background and you can customize your scripts, but Aptivia is simpe, intuitive graphical environment and you don't have to start with Skill-coding.

BR, Salmiakki

I am new to Cadence Analog Design Env.I am creating ocean script using ADE window.The script is showing the path of a stimulus file (*scs) but the file is not being created and thus the simulation I am running is taking all the stimuli as zero.Can anyone help in this regard?


Added after 39 minutes:


I am new to Cadence Analog Design Env.I am creating ocean script using ADE window.The script is showing the path of a stimulus file (*scs) but the file is not being created and thus the simulation I am running is taking all the stimuli as zero.Can anyone help in this regard?


The next is copy-pasted from Ocean reference:

stimulusFile( t_fileName [t_fileName2 … t_fileNameN ] [?xlate
b_xlate] ) => l_fileNames/nil
Specifies stimulus files to be used by the simulator.
When the b_xlate variable is set to t, the schematic net expressions [#net] and instance
name expression [$instance] in the stimulus file are mapped into simulator names before
including. When a netlist is specified as the design, this option must be set to nil.
Note: This command does not work with socket simulators.
t_fileName The name of the stimulus file to be included.
The names of the additional stimulus files to be included.
b_xlate If set to t, net and instance expressions are translated to
simulator names. The default value of the b_xlate variable is
Value Returned
l_fileNames A list of the stimulus file names is output if the command is
nil Otherwise nil is returned
stimulusFile( "tran.stimulus rf.stimulus" ?xlate nil) =>
("tran.stimulus rf.stimulus")
Includes tran.stimulus and rf.stimulus in the simulator input file. No net and instance
expressions are translated.

Okei, I think you have to create stimulus by yourself and then call you stimuli by Ocean script.



How do I create the stimulus file?Using skill?I am not famaliar with skill language.Is there any document/help for creating stimulus file?Please let me know.


I think the format and contents of stimulus file depends on what simulator you're using (spectre, eldo) and what kind of stimulus simulator can use. Stimulus could be for example digital data burst to your DAC-path. It may be voltage values in .txt format.

What are you putting into your stimulus file?`


I am using TI Spice, tol similar to Hspice and the stimulis are voltages only.What is the format to define voltage signals at the nodes?


Added after 1 hours 59 minutes:


I tried selecting the simulator as Specter and then created the ocean script using the ADE.The file mentioned in the ocean script (stimulus file) is actually created and the simulation with specter is running from the ocean command line.When I use this stimulus file with the TI spice simulator, the simulation does not take/identify the stimulus file.It means that the stimulus file syntax depend on the simulator chosen and it does not have generic skill language format.Please comment in this regard.


well i'm using TSMC 130 n RF kit under mentor environment... if u want to include all the files at once than in the model folder where u have installed the kit u can find a file named 'include.all'

this is the file which includes the paths of all the simulation libraries that are available.. just include that file.. and u are done.. while running the simulation... i will automatically run the necessary simulation...
i hope this will work.. try and do let me know...
good luck


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