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Design Languages >> Verilog-AMS >> how 2 use "wreal"
https://designers-guide.org/forum/YaBB.pl?num=1262766115

Message started by sand_dolphin2 on Jan 6^th, 2010, 12:21am

Title: how 2 use "wreal"
Post by sand_dolphin2 on Jan 6^th, 2010, 12:21am

i'm digital engineer. in these days our team make mixed signal chip.
so, in the first step of system level simulation we use verilog-AMS.

in these days, we found the variable of "wreal" :o
but does not well know about this. :'(

plz let me know the start up 2 use "wreal"

like as topic of verilog-AMS
http://www.designers-guide.org/Forum/YaBB.pl?num=1259671207

i'll wait for your kind.

this topic is only the first step of 2 use "wreal"
　for top down system level simulation!!

ciao :-)

Title: Re: how 2 use "wreal"
Post by Andrew Beckett on Jan 6^th, 2010, 10:13am

If you're using Cadence's AMS Designer simulator, look in:

<IUSHome>/doc/wreal/wreal.pdf

This is in IUS82 and INCISIV92/IUS92 (I didn't check others as I only looked quickly).

The sample files mentioned in this Real Valued Modeling Guide are in:

<IUSHOME>/tools/affirma_ams/etc/wrealSamples

Regards,

Andrew.

Title: Re: how 2 use "wreal"
Post by sand_dolphin2 on Jan 20^th, 2010, 8:11pm

^Andrew Beckett

thx for your kind.
so i'll try to run wrealSmples... fist step PLL.

so, plz give some advice for negative issue.

positive:
simulator is running faster than electrical

negative:
　lost real behavior during sampling freq of wreal...

let me know what kind of things we should care about ?? :-/

i'll wait for your kind.
if you give some info
　　　　with making SoC fault case, very helpful for me... 8-)

ciao :-)

Title: Re: how 2 use "wreal"
Post by Andrew Beckett on Jan 21^st, 2010, 6:34am

Unfortunately your question is rather vague - so I don't really know what you're asking me. If you're asking me to describe every possible problem you could have when using wreal, that's not really practical!

Please be more specific. I don't know what you're actually trying to do, and without knowing that, it's hard to give you an answer.

Regards,

Andrew.

Title: Re: how 2 use "wreal"
Post by Riad KACED on Jan 21^st, 2010, 3:44pm

Hi sand_dolphin2,

I have worked with wreal modeling over the past months. Yes, wreal saves you the analog simulator shortcomings, i.e. speed and convergence by problems.

The one thing I would advise is about modeling currents in wreal. The Electrical/Real connect modules convert real numbers into voltages. The notion of current is not conserved with wreals. And generally speaking, do not try to model whatever it is possible to model. Just stick at what you really need to model. This remark stands for wreal as well as general behavioural modeling.

My experience with wreal is rather good.
Every single design has got it's own challenges. So please put your hands on and you are very welcome to share any issues you might encounter by then.

Regards,
Riad.

Title: Re: how 2 use "wreal"
Post by Andrew Beckett on Jan 22^nd, 2010, 7:54am

Riad,

Actually you can model currents - search in the document I referenced previously for wreal_current . It's just that you can't model both voltage and current together, because the wreal represents a signal flow representation.

Regards,

Andrew

Title: Re: how 2 use "wreal"
Post by sand_dolphin2 on Feb 11^th, 2010, 5:55pm

Thanks all,

anyway , i can get no results w/o trying to start modeling...

thx!!

so, the actual question is

if u had some trouble on chip behavior , that is differ from
simulate by using wreal and check function to tape out the
Mask of chip's. :'(
　
　
that experience is good for me not to make same problem...
only this the reason to ask all...

ciao :-)

Title: Re: how 2 use "wreal"
Post by Riad KACED on Mar 2^nd, 2010, 11:09pm

Hi Andrew,

Apologies for the late answer, I was away of this forum for a while ...
OK, that's clearer, I'll look back at the doc again, more carefully this time ... :-)

Cheers,
Riad.

Title: Re: how 2 use "wreal"
Post by Riad KACED on Mar 2^nd, 2010, 11:12pm

Hi sand_dolphin2,

Many of us have taped out successful chips with wreal models. There are some papers in the literature about it.

My motto for this kind of concerns is: If you don't try, you never find out !

Cheers,
Riad.

Title: Re: how 2 use "wreal"
Post by sand_dolphin2 on Mar 8^th, 2010, 1:45am

Andrew Beckett wrote on Jan 22^nd, 2010, 7:54am:

Riad,
It's just that you can't model both voltage and current together
Andrew

thx, sorry for asking u before checking wreal_current....

so, can i use wreal_voltage and wreal_current on other module
　on one simulation ?

i guess i can , cos only 64bit real_value.

am i correct? ::)

Best Regards,

Title: Re: how 2 use "wreal"
Post by Andrew Beckett on Mar 8^th, 2010, 1:54pm

Yes, of course, you can have wreal_current and wreal_voltage disciplines in the same design - but a single node cannot be both (that's what I meant when I said that they can't be used together).

Regards,

Andrew.