[time-nuts] Spice simulation of PSRR and phase noise

Rafael Gajanec rgajanec at vercet.com
Sat Oct 28 07:36:40 EDT 2017

Hi Attila,

On 27-Oct-17 8:25 PM, Attila Kinali wrote:
> Hi Rafael
> On Sun, 22 Oct 2017 17:20:52 +0200
> Rafael Gajanec<rgajanec at vercet.com>  wrote:
>> you haven't specified what sort of circuits would you like to simulate,
> Simplified, they are differential amplifiers driven into saturation.
> A bit more detailed, I am looking at ring oscillator stages and sine-to-square
> conversion circuits and their behaviour regarding various key factors
> (note: I am not sure what the key factors are, yet)
Oscillator design - that's what I found HB simulation particularly 
useful for. It gives you almost instant results, compared to the 
transient simulation, say 10 seconds instead of 5 hours! Just imagine 
what it means if you are trying to tune several parameters of an 
oscillator... The only other reasonably fast and accurate way I can 
think of is to build the bloody circuit and measure it using some 
expensive equipment.
>> but maybe the answer is Harmonic Balance.
> Hmm.. I didn't know about Harmonic Balance. I have some reading up to do.
> Thanks!
>> HSPICE from Synopsis and ADS from Keysight (which I use) also have the
>> HB engine.
> I am mostly using ngpsice, because it's very easy to script (I have a bunch
> of perl scripts that feed simulations into a Grid Engine cluster, extract
> data and analyzse it). Is there any big advantage of the commercial spice
> engines that would make them worth considering? And would the license alow
> to run hundreds of instances in parallel?
> (Yes, I am doing crazy things :-)
Attached are some results of a simple transient simulation using Hspice 
M 2017.03, BBspice A/D 5.2.3 and ADS 2016.01. It's basically *V1 1 0 SIN 
0 1 1Meg *and then *.FOUR 1Meg V(1)* in Hspice, VspecTran in ADS and 
spectra computed using postprocessor in BBspice and ADS. As you can see, 
there are some differences... To be fair, possibly there are some 
simulator-specific settings/methods that could improve the results and 
you should figure it out yourself what's the way to get the best results 
from your spice. See 

Commercial spice engines may have lower computational noise and shorter 
simulation times. For example my out-dated BBspice (which is commercial 
too by the way) crashed several times before I got some results, while 
it used little RAM and only about 10-12% of available processor 
resources... I intended to get you Pspice results of this simulation as 
well, but I gave up after half an hour and about 1% of progress.

> 			Attila Kinali

Best regards,
Rafael Gajanec
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Hspice.png
Type: image/png
Size: 43277 bytes
Desc: not available
URL: <http://www.febo.com/pipermail/time-nuts/attachments/20171028/b3675c71/attachment-0003.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: BBspice.png
Type: image/png
Size: 23045 bytes
Desc: not available
URL: <http://www.febo.com/pipermail/time-nuts/attachments/20171028/b3675c71/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ADS.png
Type: image/png
Size: 35890 bytes
Desc: not available
URL: <http://www.febo.com/pipermail/time-nuts/attachments/20171028/b3675c71/attachment-0005.png>

More information about the time-nuts mailing list