The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Simulators >> RF Simulators >> PSS predicts a wrong oscillating frequency !!!
https://designers-guide.org/forum/YaBB.pl?num=1112854723

Message started by Alez on Apr 6^th, 2005, 11:18pm

Title: PSS predicts a wrong oscillating frequency !!!
Post by Alez on Apr 6^th, 2005, 11:18pm

Hi all,

seems to have many problems from VCO simulation :O

I'm simulating a VCO and I found an error from PSS.

From my simulation, in transient analysis, I found that

the VCO oscillates at 2.8 GHz (by measuring the period

of the output waveform). But from PSS, it shows that

the oscillating frequency is 3.5 GHz !!! How come ???

I tried to set many different "tstab" and different time

interval (tstart tstop) in transient simulation, but PSS

always shows 3.5 GHz !!

Could anyone explain me about this problem and how

to solve it,

Thank you all in advance,

Alez :)

Title: Re: PSS predicts a wrong oscillating frequency !!!
Post by Andrew Beckett on Apr 7^th, 2005, 1:31pm

Please don't post the same question in multiple fora - it makes it harder to keep track of.

I responded to this in the RF Design Forum. I suggest anyone else does so there, since it's been started there.

Regards,

Andrew.

Title: Re: PSS predicts a wrong oscillating frequency !!!
Post by Alez on Apr 8^th, 2005, 12:17am

Andrew,

not sure what you mentioned. You mean I also posted in this

question in the RF Design forum ....

strange !

I think I only posted it here ??

If I were wrong, meaning I did some mistake :(

Could you bring me my question in the RF Design forum

Thanks,

Alez

Title: Re: PSS predicts a wrong oscillating frequency !!!
Post by Andrew Beckett on Apr 8^th, 2005, 6:20am

Hi Alez,

My apologies. A very similar question was posted by someone else, and I assumed it was the same person.

I should try being awake when I post...

One problem might be what I described there:

http://www.designers-guide.org/Forum/?board=rfdesign;action=display;num=1112820269

Another problem might be that when you're looking at the output waveform, I assume you're looking at the initial transient, or a separate transient run. What may happen is that this is not the final, settled, frequency.

Remember that PSS accellerates settling, and so it may be that you need to run a very long transient to see it settling on 3.5GHz.

Regards,

Andrew