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Design Languages >> Verilog-AMS >> Using analogLib components with verilog-AMS
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Message started by immcinto on Jan 19^th, 2010, 5:18am

Title: Using analogLib components with verilog-AMS
Post by immcinto on Jan 19^th, 2010, 5:18am

I have a fairly complex 3-phase moter model that I built a while ago using analogLib components but I would now like to drive the model using a micro that is modelled in verilog-HDL. I am using verilog-AMS to simulate but of course the simulation is much slower than if I sim only the digital section. My question is - would replacing the analogLib primitives (resistor, inductor, vcvs etc.) with the equivalent verilog-AMS models cut the sim time significantly (order-of-magnitude)? I realize the verilog-AMS version would be a bit quicker due to less translation etc. but I believe that the Spectre simulator still has to be used for the analog components realized in verilog-AMS so I suspect I would not see a greatly reduced sim time. correct? Are there any other techniques that I could use to speed up the sim?

thanks for any help.
.jim.

Title: Re: Using analogLib components with verilog-AMS
Post by Andrew Beckett on Jan 19^th, 2010, 6:31am

A straight conversion of the analog primitives into VerilogAMS won't speed it up (if anything it could be slightly slower).

Depending on what is the root cause of the slowness, you could get it faster by writing a more direct VerilogAMS model of the motor though, but all the time it has continuous nodes (continuous in time) it will still need an analog solver (e.g. spectre) to solve and won't be as fast as the pure digital simulation.

So one approach is to use the real-number modelling technique - see <IUSinstDir>/doc/wreal/wreal.pdf (the Verilog-AMS Real Valued Modeling Guide) which shows how to use event-driven reals instead, which can be used entirely in the event-driven (i.e. digital) solver.

Regards,

Andrew.

Title: Re: Using analogLib components with verilog-AMS
Post by immcinto on Jan 19^th, 2010, 7:14am

Thanks, wreal.pdf is not in our path. Is there another I can read the documentation?

Title: Re: Using analogLib components with verilog-AMS
Post by Andrew Beckett on Jan 19^th, 2010, 10:37am

Which version of AMS are you using? (ncsim -version should tell you). I was looking in IUS82, but it will also be in INCISIV92.

Otherwise you can look this up on Cadence Online Support http://support.cadence.com - or rather you could normally, but there's been a major power failure in San Jose due to the weather there - I believe a tree has come down and taken out the power to the Cadence Campus.

Regards,

Andrew.