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

[Gerhard Hoffmann]

Am 22.10.2017 um 22:58 schrieb Bruce Griffiths:

Hoi Attila

Since close in phase noise can result from up conversion of supply noise etc 
via circuit non linearities, using an AC analysis won't work.

Only transient simulation or perhaps analytical modelling of the various non 
linearities will provide accurate estimates of upconverted PN. If you use 
transient simulation techniques increasing the level of the various noise 
sources above the actual levels encountered in real circuits and then 
correcting the resultant PN back to the level that would be encountered in the 
actual circuit (using the results of analytical modelling) may be a useful way 
to reduce simulation time or at least overcome some of the challenges 
associated with accurately determining low level PN from a simulation.

There are some in the LTSpice Yahoo group attempting this but they seem way out 
of touch with the amount of simulation data required. I've provided them with 
the appropriate formulae to extract PN from the the amplitude spectra. At the 
moment they appear bogged down with some somewhat trivial peripheral issues.


In a previous life, when I was an EE student, we had to write all the
relevant algorithms ourselves, like building the conductance matrix,
finding the operating point, linearizing nonlinear devices around the
OP, doing the integration over time, companion models etc, b4 we were
given the Spice 2G4 sources...

(Attila, that was a few 100 meters from where you seem to work right
now. There was a beautiful TR440!)

Given that we often enough see convergence problems in integration over
time to the point that the simulator gives up altogether, especially
when there are high Q resonances or nonlinearities around, and that
these errors look like phase noise, I would never ever trust a FFT
result at, say, the -140 dBc level. And there it just starts to be
interesting.

As much as I like to use LTspice, it's easy availability blocks any fast
progress in the public spices like adding HB, s-params by diverting
people to experiment with add-ons instead of solving the fundamental
issues. X/Ngspice and QUCS are nice but understaffed for sure.

regards, Gerhard.

(who was designing a chopper amplifier in the 140 pV/rt Hz league this
rainy weekend and did not even try to simulate its noise. The
interesting part of it would never make it through the pot core
transformer.)



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Re: [time-nuts] Phase Noise Modeling in SPICE

[Ulrich Rohde via time-nuts]

Eric has done a lot of excellent work, I know his presentations . While I do no 
always agree with the ADS approach and use my own software the ADS is a very 
good all-round CAD microwave CAD tool. More on the topic addressed you will 
find under 

 
 
http://www.microwavejournal.com/articles/29151-noise-analysis-then-and-today
 
Ulrich 
 
In a message dated 10/22/2017 5:53:36 PM Eastern Standard Time, 
druc...@sonic.net writes:

 
 I have done a lot of phase noise modeling using LT SPICE over the years for 
PLL’s. It will not model the phase noise of the individual devices like VCO’s, 
dividers, phase detectors. You can input the phase noise profiles of the 
various devices and it will give the output phase noise of the loop using AC 
analysis. If you want to model the phase noise of a VCO at the transistor 
level, you need a harmonic balance program that supports VCO noise modeling. It 
is very difficult to module the phase noise of dividers, at the transistor 
level but it can be done. I did a presentation a few years ago at the European 
Microwave Conference on using CAE to model phase noise in PLL’s. 



https://www.slideshare.net/edrucker1/european-microwave-pll-class



Eric Drucker

Agilent (Keysight) Technologies, Retired

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

[Bruce Griffiths]

One has to provide noise models that work with the Spice transient simulation 
for all devices including resistors. Random number generators can be used but 
they need to be independent and must not repeat during the entire simulation.

Bruce

> 
> On 23 October 2017 at 10:25 Bruce Griffiths  
> wrote:
> 
> If one for example wishes to estimate PN down to an offset of 1Hz then an 
> equivalent filter noise bandwidth of 0.1Hz or perhaps less is desirable (the 
> PN spectrum at low offsets is far from flat). To achive accurate noise 
> estimates a simulation time of at least 100 x the reciprocal of the 
> equivalent noise bandwidth is required. The resultant simulation for 1000 sec 
> or more takes considerably longer than 1000 sec to run.
> 
> Bruce
> 
> > > 
> > On 23 October 2017 at 03:23 Dana Whitlow  
> > wrote:
> > 
> > Hello Attila,
> > 
> > It seems to me that an AC simulation could never work since the
> > very generation of phase noise by the mechanisms that matter is
> > a modulation process at heart, automatically forcing one into the
> > realm of transient simulations.
> > 
> > But I am surprised about the simulation times that you speak of.
> > Would you be willing to post some information detailing your
> > methodology and an example "simple" circuit?
> > 
> > Dana
> > 
> > On Sun, Oct 22, 2017 at 7:53 AM, Attila Kinali  
> > wrote:
> > 
> > > > > 
> > > > > > > 
> > > > Hi,
> > > > 
> > > > > > > 
> > > I have been looking into spice simulations of circuits, in 
> > > particular
> > > trying to extract PSRR and phase noise information. 
> > > Unfortunatelly,
> > > the obvious way of putting AC sources at the right places 
> > > does not
> > > work, as the (ideal) input signals are not small and drive 
> > > the circuit
> > > into non-linearities. Hence I have to do transient 
> > > simulations.
> > > But extracting PSRR and phase noise information out of a 
> > > transient
> > > simulation is cumbersome at best and takes a lot of 
> > > simulation time
> > > (we are talking about hours to days for simple circuits).
> > > 
> > > I am looking for guidelines and hints how to speed things up.
> > > Maybe even being able to use standard DC and AC analysis for 
> > > the
> > > circuit instead of transient. Unfortunately, my google-foo 
> > > was not
> > > strong enough to find approriate documentation.
> > > 
> > > Does someone have any hints what I should read or search for?
> > > 
> > > Thanks in advance
> > > 
> > > Attila Kinali
> > > 
> > > --
> > > It is upon moral qualities that a society is ultimately 
> > > founded. All
> > > the prosperity and technological sophistication in the world 
> > > is of no
> > > use without that foundation.
> > > -- Miss Matheson, The Diamond Age, Neil Stephenson
> > > 
> > > ___
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > > mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > > 
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> > > and follow the instructions there.
> > > 
> > > > > > > 
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> > > > 
> > > > > > > 
> > > > > 
> > > 
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Re: [time-nuts] Sulzer 2.5 For Sale

[Tom Van Baak]

Hi Ruslan,

> this standard appears to be ancient 

Yes. Sulzer oscillators are among of the best quartz frequency standards ever 
made. Good reading:

"Brief History of the Development of Ultra-precise Oscillators for Ground and 
Space Applications"
https://ieee-uffc.org/about-us/history/uffc-s-history/brief-history-of-the-development-of-ultra-precise-oscillators-for-ground-and-space-applications/

"Design and Performance of Ultraprecise 2.5-mc Quartz Crystal Units. (Warner, 
A.W.)"

http://ieee-uffc.org/wp-content/uploads/2016/11/warner.pdf
https://ieee-uffc.org/about-us/history/uffc-s-history/

The Sulzer 2.5C and 5B oscillators are highly sought after by time-nuts, given 
the history, the space-era construction inside, and (if you're lucky, or need a 
project) the amazing e-13 level of performance out of these standards:

https://febo.com/pages/oscillators/sulzer/
http://leapsecond.com/museum/sul25-1/

You don't need to read Japanese to appreciate this wonderful set of teardown 
photos:

http://etoysbox.jp/1_TestEquipment/12_F_std/OCXO/OCXO.htm

/tvb

- Original Message - 
From: "Ruslan Nabioullin" 
To: "Discussion of precise time and frequency measurement" 
Sent: Sunday, October 22, 2017 12:55 PM
Subject: Re: [time-nuts] Sulzer 2.5 For Sale


That system clearly is a rudimentary (simply based on amplitude)
failover controller---e.g., a shoestring setup could have an EOL
cesium standard (relatively-accurate but -unreliable) that's not on
UPS and a UPS-backed OCXO (like this unit) (relatively-inaccurate but
-reliable) connected to ``REF IN'' and ``STBY IN'', resp.  Honestly
this standard appears to be ancient and the high-level build quality
appears to be questionable.

-Ruslan

On Sat, Oct 21, 2017 at 10:05 PM, Richard Mogford  wrote:
> Hello
>
> I am selling a Sulzer 2.5 frequency standard.It is rack mounted with a
> separate power supply and no battery.It also has an “Amplitude Fault
> System.”(I have not been able to find out what this does.) There is a PDF
> manual that I will send the buyer with the equipment.  The switch setting #4
> shows zero milliamps.
>
> I am not an expert in these devices by any means, but have been running the
> Sulzer for several days using John Miles’ excellent TimeLab software.I have
> pasted in below an Allen Deviation plot for three days of data collection.
>
> I will be selling the Sulzer on auction on eBay starting on Monday, October
> 23.The starting bid will be $200.Shipping may be around $50.
>
>
> Please contact me if you have any questions.
>
>
> Richard
> AE6XO
> rch...@earthlink.net
>


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[time-nuts] Phase Noise Modeling in SPICE

[Eric Drucker]

I have done a lot of phase noise modeling using LT SPICE over the years for 
PLL’s. It will not model the phase noise of the individual devices like VCO’s, 
dividers, phase detectors. You can input the phase noise profiles of the 
various devices and it will give the output phase noise of the loop using AC 
analysis. If you want to model the phase noise of a VCO at the transistor 
level, you need a harmonic balance program that supports VCO noise modeling. It 
is very difficult to module the phase noise of dividers, at the transistor 
level but it can be done. I did a presentation a few years ago at the European 
Microwave Conference on using CAE to model phase noise in PLL’s. 

 

https://www.slideshare.net/edrucker1/european-microwave-pll-class

 

Eric Drucker

Agilent (Keysight) Technologies, Retired

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

[Bruce Griffiths]

If one for example wishes to estimate PN down to an offset of 1Hz then an 
equivalent filter noise bandwidth of 0.1Hz or perhaps less is desirable (the PN 
spectrum  at low offsets is far from flat). To achive accurate noise estimates 
a simulation time of at least 100 x the reciprocal of the equivalent noise 
bandwidth is required. The resultant simulation for 1000 sec or more takes 
considerably longer than 1000 sec to  run. 

Bruce

> 
> On 23 October 2017 at 03:23 Dana Whitlow  wrote:
> 
> Hello Attila,
> 
> It seems to me that an AC simulation could never work since the
> very generation of phase noise by the mechanisms that matter is
> a modulation process at heart, automatically forcing one into the
> realm of transient simulations.
> 
> But I am surprised about the simulation times that you speak of.
> Would you be willing to post some information detailing your
> methodology and an example "simple" circuit?
> 
> Dana
> 
> On Sun, Oct 22, 2017 at 7:53 AM, Attila Kinali  wrote:
> 
> > > 
> > Hi,
> > 
> > I have been looking into spice simulations of circuits, in 
> > particular
> > trying to extract PSRR and phase noise information. Unfortunatelly,
> > the obvious way of putting AC sources at the right places does not
> > work, as the (ideal) input signals are not small and drive the 
> > circuit
> > into non-linearities. Hence I have to do transient simulations.
> > But extracting PSRR and phase noise information out of a transient
> > simulation is cumbersome at best and takes a lot of simulation time
> > (we are talking about hours to days for simple circuits).
> > 
> > I am looking for guidelines and hints how to speed things up.
> > Maybe even being able to use standard DC and AC analysis for the
> > circuit instead of transient. Unfortunately, my google-foo was not
> > strong enough to find approriate documentation.
> > 
> > Does someone have any hints what I should read or search for?
> > 
> > Thanks in advance
> > 
> > Attila Kinali
> > 
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of 
> > no
> > use without that foundation.
> > -- Miss Matheson, The Diamond Age, Neil Stephenson
> > 
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> > 
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to 
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> > 
> > > 
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Bruce Griffiths]

Hoi Attila

Since close in phase noise can result from up conversion of supply noise etc 
via circuit non linearities, using an AC analysis won't work.

Only transient simulation or perhaps analytical modelling of the various non 
linearities will provide accurate estimates of upconverted PN. If you use 
transient simulation techniques increasing the level of the various noise 
sources above the actual levels encountered in real circuits and then 
correcting the resultant PN back to the level that would be encountered in the 
actual circuit (using the results of analytical modelling) may be a useful way 
to reduce simulation time or at least overcome some of the challenges 
associated with accurately determining low level PN from a simulation.

There are some in the LTSpice Yahoo group attempting this but they seem way out 
of touch with the amount of simulation data required. I've provided them with 
the appropriate formulae to extract PN from the the amplitude spectra. At the 
moment they appear bogged down with some somewhat trivial peripheral issues.

Bruce

> 
> On 23 October 2017 at 01:53 Attila Kinali  wrote:
> 
> Hi,
> 
> I have been looking into spice simulations of circuits, in particular
> trying to extract PSRR and phase noise information. Unfortunatelly,
> the obvious way of putting AC sources at the right places does not
> work, as the (ideal) input signals are not small and drive the circuit
> into non-linearities. Hence I have to do transient simulations.
> But extracting PSRR and phase noise information out of a transient
> simulation is cumbersome at best and takes a lot of simulation time
> (we are talking about hours to days for simple circuits).
> 
> I am looking for guidelines and hints how to speed things up.
> Maybe even being able to use standard DC and AC analysis for the
> circuit instead of transient. Unfortunately, my google-foo was not
> strong enough to find approriate documentation.
> 
> Does someone have any hints what I should read or search for?
> 
> Thanks in advance
> 
> Attila Kinali
> 
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Rafael Gajanec]

Dear Attila,

you haven't specified what sort of circuits would you like to simulate, 
but maybe the answer is Harmonic Balance. Have a look at 
http://qucs.sourceforge.net/ and 
http://qucs.sourceforge.net/tech/node36.html


HSPICE from Synopsis and ADS from Keysight (which I use) also have the 
HB engine.


Best regards,
Rafael Gajanec


On 22-Oct-17 4:23 PM, Dana Whitlow wrote:

Hello Attila,

It seems to me that an AC simulation could never work since the
very generation of phase noise by the mechanisms that matter is
a modulation process at heart, automatically forcing one into the
realm of transient simulations.

But I am surprised about the simulation times that you speak of.
Would you be willing to post some information detailing your
methodology and an example "simple" circuit?

Dana

On Sun, Oct 22, 2017 at 7:53 AM, Attila Kinali  wrote:


Hi,

I have been looking into spice simulations of circuits, in particular
trying to extract PSRR and phase noise information. Unfortunatelly,
the obvious way of putting AC sources at the right places does not
work, as the (ideal) input signals are not small and drive the circuit
into non-linearities. Hence I have to do transient simulations.
But extracting PSRR and phase noise information out of a transient
simulation is cumbersome at best and takes a lot of simulation time
(we are talking about hours to days for simple circuits).

I am looking for guidelines and hints how to speed things up.
Maybe even being able to use standard DC and AC analysis for the
circuit instead of transient. Unfortunately, my google-foo was not
strong enough to find approriate documentation.

Does someone have any hints what I should read or search for?

Thanks in advance

 Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
  -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Sulzer 2.5 For Sale

[Ruslan Nabioullin]

That system clearly is a rudimentary (simply based on amplitude)
failover controller---e.g., a shoestring setup could have an EOL
cesium standard (relatively-accurate but -unreliable) that's not on
UPS and a UPS-backed OCXO (like this unit) (relatively-inaccurate but
-reliable) connected to ``REF IN'' and ``STBY IN'', resp.  Honestly
this standard appears to be ancient and the high-level build quality
appears to be questionable.

-Ruslan

On Sat, Oct 21, 2017 at 10:05 PM, Richard Mogford  wrote:
> Hello
>
> I am selling a Sulzer 2.5 frequency standard.It is rack mounted with a
> separate power supply and no battery.It also has an “Amplitude Fault
> System.”(I have not been able to find out what this does.) There is a PDF
> manual that I will send the buyer with the equipment.  The switch setting #4
> shows zero milliamps.
>
> I am not an expert in these devices by any means, but have been running the
> Sulzer for several days using John Miles’ excellent TimeLab software.I have
> pasted in below an Allen Deviation plot for three days of data collection.
>
> I will be selling the Sulzer on auction on eBay starting on Monday, October
> 23.The starting bid will be $200.Shipping may be around $50.
>
>
> Please contact me if you have any questions.
>
>
> Richard
> AE6XO
> rch...@earthlink.net
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Dana Whitlow]

Hello Attila,

It seems to me that an AC simulation could never work since the
very generation of phase noise by the mechanisms that matter is
a modulation process at heart, automatically forcing one into the
realm of transient simulations.

But I am surprised about the simulation times that you speak of.
Would you be willing to post some information detailing your
methodology and an example "simple" circuit?

Dana

On Sun, Oct 22, 2017 at 7:53 AM, Attila Kinali  wrote:

> Hi,
>
> I have been looking into spice simulations of circuits, in particular
> trying to extract PSRR and phase noise information. Unfortunatelly,
> the obvious way of putting AC sources at the right places does not
> work, as the (ideal) input signals are not small and drive the circuit
> into non-linearities. Hence I have to do transient simulations.
> But extracting PSRR and phase noise information out of a transient
> simulation is cumbersome at best and takes a lot of simulation time
> (we are talking about hours to days for simple circuits).
>
> I am looking for guidelines and hints how to speed things up.
> Maybe even being able to use standard DC and AC analysis for the
> circuit instead of transient. Unfortunately, my google-foo was not
> strong enough to find approriate documentation.
>
> Does someone have any hints what I should read or search for?
>
> Thanks in advance
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
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[time-nuts] Spice simulation of PSRR and phase noise

[Attila Kinali]

Hi,

I have been looking into spice simulations of circuits, in particular
trying to extract PSRR and phase noise information. Unfortunatelly,
the obvious way of putting AC sources at the right places does not
work, as the (ideal) input signals are not small and drive the circuit
into non-linearities. Hence I have to do transient simulations.
But extracting PSRR and phase noise information out of a transient
simulation is cumbersome at best and takes a lot of simulation time
(we are talking about hours to days for simple circuits).

I am looking for guidelines and hints how to speed things up.
Maybe even being able to use standard DC and AC analysis for the
circuit instead of transient. Unfortunately, my google-foo was not
strong enough to find approriate documentation.

Does someone have any hints what I should read or search for?

Thanks in advance

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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