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Simulators >> Circuit Simulators >> Skill script for eye diagram measurements
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Message started by avlsi on Mar 27^th, 2009, 12:01am

Title: Skill script for eye diagram measurements
Post by avlsi on Mar 27^th, 2009, 12:01am

Hi all,

Can any one provide me the skill script for eye diagram measurements.

Thanks in advance

Title: Re: Skill script for eye diagram measurements
Post by pancho_hideboo on Mar 27^th, 2009, 3:17am

avlsi wrote on Mar 27^th, 2009, 12:01am:

Can any one provide me the skill script for eye diagram measurements.

I can't know what measurements you want to do. Simple aperture Ratio ? There are many measurements in eye diagram.
http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=1486728&nid=-34333.870778.00&id=1486728&cmpid=29870
Page-30 of http://eesof.tm.agilent.com/pdf/ads2005a_whats_new.pdf
http://www.designers-guide.org/Forum/YaBB.pl?num=1209812189

You don't specify vendor's name of tools you use.
But if you use Cadence Design Environment and simply want to plot eye diagram, enter "ocnHelp 'eyeDiagram" in CIW.

Quote:

eyeDiagram ( o_waveform n_start n_stop n_period ) => o_waveform/nil
Description
This function gives an eye-diagram plot of the input waveform signal. It returns the waveform object of the eye-diagram plot.

Arguments
n_start : x-axis start value from where the eye-diagram plot is to commence
n_stop : x-axis stop value where the eye-diagram plot will terminate
n_period : period value

Value Returned
o_waveform : Returns a waveform object representing the eye-diagram plot of the input waveform
nil : Returns nil and an error message otherwise

Example
eyeDiagram( v("/out" ) 0n 500n 12.5n)

Title: Re: Skill script for eye diagram measurements
Post by avlsi on Mar 29^th, 2009, 7:10pm

I am sorry with the ambiguity in my request.

I was able plot the eyediagram.

I am using Spectre as my simulation tool with the sub version 5.10.41

I need to measure the
Eye Amplitude
Eye Crossing Amplitude
Eye Crossing Percentage
Eye Height
Eye Level
Eye SNR
Quality Factor
Vertical Eye Opening
Time Measurements
Deterministic Jitter
Eye Crossing Time
Eye Delay
Eye Fall Time
Eye Rise Time
Eye Width
Horizontal Eye Opening
Peak-to-Peak Jitter
Random Jitter
RMS Jitter
Total Jitter

Thanks in advance.

Title: Re: Skill script for eye diagram measurements
Post by pancho_hideboo on Mar 30^th, 2009, 1:49am

avlsi wrote on Mar 29^th, 2009, 7:10pm:

I need to measure the
Eye Amplitude
Eye Crossing Amplitude
Eye Crossing Percentage
Eye Height
Eye Level
Eye SNR
Quality Factor
Vertical Eye Opening
Time Measurements
Deterministic Jitter
Eye Crossing Time
Eye Delay
Eye Fall Time
Eye Rise Time
Eye Width
Horizontal Eye Opening
Peak-to-Peak Jitter
Random Jitter
RMS Jitter
Total Jitter

As you know, if you use Agilent Tools, all these measurements are prepared.

But in Cadence Environment, you have to create models for these measurements by yourself.

I have some models, but don't have all models for your measurements.

I don't know whether Cadence new waveform viewer, ViVA(Virtuoso Visualisation and Analysis) have these measurements.

Title: Re: Skill script for eye diagram measurements
Post by avlsi on Mar 30^th, 2009, 10:49pm

Can u please share the models which you have.

Thank u very much.

Title: Re: Skill script for eye diagram measurements
Post by Andrew Beckett on Mar 31^st, 2009, 3:04am

You may find sourcelink.cadence.com solution 11395772 useful - this kind of calculation can be the basis of a number of eye diagram metrics. See also solution 11018920 which shows getting a histogram of edge crossings (you can get this by using 11395772 and the IC613 histo calculator function too).

Best Regards,

Andrew.

Title: Re: Skill script for eye diagram measurements
Post by avlsi on Mar 31^st, 2009, 3:56am

Thanks for the reference Andrew.

I am a beginner in the skill scripting. So, can u just jot the commands to make use of the above script.

I have done the steps like
1. load("abEyeHisto.il")
2. plot(abEyeHisto(VT("/output") 0 1u 2n 0.5 1))
According to my understanding i have given the inputs thinking as start=0;stop=1u;period=2n;threshold=0.5;risisng edge

The resulted plot is a single point .

Please let me know where i am going wrong.

Title: Re: Skill script for eye diagram measurements
Post by Andrew Beckett on Mar 31^st, 2009, 9:11am

You can make life simpler for yourself by calling

Code:

abRegEyeHistoSpecialFunction()

and

Code:

abRegEyeCrossSpecialFunction()

in the case of the eye cross code. This will register the two functions as special functions in the calculator (look in the Special Functions pulldown in the AWD calculator, or in the "User Defined Special Functions" choice in wavescan/ViVA).

Then you have a form to fill in to build the expression for you (I really should update the solutions to make this clearer).

However, the problem with your expression is that the last argument is not indicating a rising edge, but indicating that you want 1 bin - hence the single point. If you want rising edge, and 10 bins (say), it would be:

Code:

plot(abEyeHisto(VT("/output") 0 1u 2n 0.5 10 "rising"))

I think a later version of the code (not the one on sourcelink at the moment) automatically makes the waveform draw as a histogram - I'll aim to update the sourcelink solution too when I fix the comments.

Regards,

Andrew.

Title: Re: Skill script for eye diagram measurements
Post by avlsi on Apr 1^st, 2009, 2:24am

Thank u very much for the help Andrew.

I was able to register the eyeHisto and eyeCross user defined functions.

From the eyecross function the output is a plot between crossover point value and the no.of hits. The average function of the above plot gives me a average cross over point.

And by doing the standard deviation of the eyecross plot gives a rmsjitter value.

Can u please help me to find the
1.eye vertical opening
2.Rise time of eye
3.Fall time of eye

Eagerly waiting .

Title: Re: Skill script for eye diagram measurements
Post by avlsi on Apr 3^rd, 2009, 1:28am

How to plot the vertica histogram of an eye diagram using the skill script.

:-?