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Simulators >> Circuit Simulators >> Transient noise simulation for delta-sigma ADC?
https://designers-guide.org/forum/YaBB.pl?num=1190421464

Message started by mohta on Sep 21^st, 2007, 5:37pm

Title: Transient noise simulation for delta-sigma ADC?
Post by mohta on Sep 21^st, 2007, 5:37pm

Hello,

Does anyone have any experience with Spectre's new transient noise simulation for switched-capacitor delta-sigma ADCs so that quantization and thermal noise can be captured at the same time?

Thanks,
mohta

Title: Re: Transient noise simulation for delta-sigma ADC
Post by Stefan on Sep 22^nd, 2007, 4:39am

Yes.
But I think that wasn't the answer you were looking for :)
The problem with transient noise & sigma delta ADC's is just that the simulation time really raises like hell ...

Title: Re: Transient noise simulation for delta-sigma ADC
Post by mohta on Sep 23^rd, 2007, 3:34pm

Thanks for your post Stefan.

I know that simulation time is greatly increased with transient noise. However, transient simulation itself (and transient noise as an "add-on" that modifies operating point information at each time step) is supposedly vastly more efficient these days - Berkeley Design Automation's Analog FastSpice is promising 5-10X faster transient simulation than Spectre, so it may make transient noise simulation on delta-sigma ADCs a practical reality in the near future (even if it is a "start simulation on Friday night, view results Monday morning" sort of thing).

My question was more directed towards the theoretical validity of this approach - assuming you had the time/resources/tools to do a transient noise simulation, then is it a reasonable way to capture thermal/quantization noise simultaneously in a a delta-sigma ADC? If nothing else, it can give additional validation of system level simulations and hand calculations (e.g. Ken Kundert's paper on device noise modeling in delta-sigma ADCs).

I have another thought/question: just like we have different sampling methods in Monte Carlo analysis (like Latin Hypercube Sampling) to get an idea of the worst-case spread without running a huge number of Monte Carlo runs, is it possible for transient noise analysis to give a realistic estimate of the combined noise with fewer runs? Would running a small number of simulations starting from different seed values (and using some clever sampling technique) be equivalent to running one simulation for a longer amount of time?

Thanks,
mohta

Title: Re: Transient noise simulation for delta-sigma ADC
Post by Stefan on Sep 27^th, 2007, 12:09am

running smaller simulations with different seed values does in fact produce the same simulation results than running a longer simulation (random input supposed).

But - the simulation duration is the same :) (although you could easier parallelize this ...)