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Design Languages >> Verilog-AMS >> Comparison between ams simulator and spectre
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Message started by subtr on Dec 30^th, 2016, 12:49am

Title: Comparison between ams simulator and spectre
Post by subtr on Dec 30^th, 2016, 12:49am

I have simulated verilogA with Spectre. I have also done simulation of verilogAMS simulation using AMS simulator. Is there a performance/Speed Comparison ams Simulator between spectre given I create a block both in vams and va doing the same functionality?

I was just wondering if the va and vams are treated differently because I found that running a verilogA + a vams in ams simulator caused the simulation to be very slow and not converge. Convergence was achieved when the vams was run in ams & va file in spectre separately. Both were doing the same functionality of punching some cross points into a file.

Title: Re: Comparison between ams simulator and spectre
Post by Andrew Beckett on Dec 30^th, 2016, 1:52am

In general I wouldn't expect the difference to be significant. The VerilogA code is compiled to C (at least parts of it) and that may give some small speed benefits for the spectre engine - however, the analog parts of VerilogAMS are also simulated in the spectre engine. So there are differences, but it should not be massive - and in most reasonable circuits I wouldn't expect there to be a difference. In essence, the AMS simulator is a single simulator which uses both a digital "solver" (the event-driven Incisive engine) and an analog solver (spectre, APS, XPS-MS, or UltraSim).

It may make sense to contact Cadence to take a look at your specific examples to help understand what the difference is - or if it's small enough (and you can share it in public), share the example here?

Regards,

Andrew.

Title: Re: Comparison between ams simulator and spectre
Post by subtr on Dec 30^th, 2016, 11:41am

Hi Andrew,

The simulation takes a long time before it finds convergence issue. Since it's resolved, I wouldn't want to take it up again. I think you have answered my question. I wanted to fundamentally know whether ams simulator is totally different from spectre or that the spectre is part of it which takes care of the analog part of it. So I assume, that if I have a verilogA file, the ams simulator and spectre would treat the file more or less the same way. Thank you Andrew :)