Analog Simulation Insights


more British accents… on SPICE accuracy

Hello Everyone,

I suppose that I should just declare today “Hail Britannia” day here at Analog Insights. Hopefully, you have already read my post from earlier today on “Spicing things up”… with a British accent. Maybe you also have noticed my Blogroll over on the the left side of this blog page, with the link to my friend Simon Young’s blog at “All About EDA”. Well, to further add to today’s “British Invasion“, I just came across another interesting technology blog with the unlikely name of “Hacking Cough”. Maybe that’s a reference to a Monty Python skit that I missed… I don’t know. 🙂

In any case, the author of Hacking Cough (Chris Edwards) wrote recently on one of my favorite issues – SPICE accuracy. You can read about it in “EDA’s Acceleration Option“. As it turned out, that article was an interesting precursor to my recent post on simulation accuracy, Simulation accuracy… it’s the silicon, ******!

I was compelled to join the discussion over at “Hacking Cough”, and I thought I would share my comments with you here as well:


Hi Chris,

Your article popped up in my Google search widget today, due to Simon Young’s reference to my Analog Insights blog. I also found your original article to be very interesting, especially the point about SPICE accuracy and single-precision. There is so much mis-information being published on the topic of SPICE accuracy these days that it has become one of my pet peeves. One of my recent articles on the topic is Simulation accuracy… it’s the silicon, ******!

If you talk about SPICE accuracy you have to start with HSPICE, which is the incumbent gold-standard that everyone else tries to compare to. As was noted in Simon’s comment, since HSIM is part of the same Synopsys Discovery-AMS product family as HSPICE – it has the luxury of sharing the same gold-standard models.

The comment about how multi-threading model evaluation in SPICE can impact performance is valid, but why rely on a “secret sauce” when you can get the real thing from the trusted standard? You can read some of the latest news about how HSPICE has accelerated simulation through multi-threading here: Synopsys HSPICE Delivers Innovative Technology to Accelerate Circuit Simulation Performance. HSPICE provides more than just acceleration of model evaluation, by also accelerating analysis on multi-core platforms.

Finally, Yes – I can show how HSIM Fast-SPICE can give a designer even greater accuracy than SPICE. And it’s no “trick”! With all the misguided focus on simulator “accuracy” comparisons you will find that even designers will sometimes forget what the objective is… It’s the silicon! Not the simulation! HSIM and HSIMplus can give a more accurate representation of the silicon in post-layout simulations, because SPICE is very limited in the capacity to handle the millions of parasitic elements that are introduced when you actually build a circuit.

Thanks for the opportunity to weigh-in on this important subject. I will definitely being watching your blog more in the future.

-Mike Demler

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