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questions about PSS simulation (Read 3754 times)
LeonQQ
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questions about PSS simulation
Mar 03rd, 2010, 11:39am
 
Hi Folks,

I am simulating a mixer. I wonder how to specify the LO frequency value in the PSS simulation menu, if the LO frequency is coming from a transistor-level VCO?

If I use a ideal voltage source as the LO clock, I can specify the frequency value that I want, then the simulator can know it. But now the LO frequency is coming from a VCO, I ran the PSS simulation and found the simulator cannot figure out the LO frequency, then the frequency down-conversion was failed. I need to tell the simulator how much the LO frequency is, but I don't know where I can name it and give the value.

Thank you very much for the help.

Leon
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pancho_hideboo
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Re: questions about PSS simulation
Reply #1 - Mar 3rd, 2010, 3:15pm
 
What EDA vendor's simulator do you mean as "PSS" ?
There are many simulators which have analysis called as PSS.
Always describe vendor's name which you use as tool or simulator.

See http://www.designers-guide.org/Forum/YaBB.pl?num=1227668750
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sheldon
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Re: questions about PSS simulation
Reply #2 - Mar 3rd, 2010, 7:58pm
 
Leon,

  In almost all designs a VCO is not run open loop, it is part of a PLL.
The PLL will control the VCO oscillation frequency.  So the LO sources
for the Mixer can be set a frequency determined by application/
specification. If in your case, if you are running the VCO open-loop,
then PSS is not the appropriate analysis. There are other tools
available for this problem.

                                                         Best Regards,

                                                           Sheldon
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pancho_hideboo
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Re: questions about PSS simulation
Reply #3 - Mar 4th, 2010, 12:24am
 
sheldon wrote on Mar 3rd, 2010, 7:58pm:
If in your case, if you are running the VCO open-loop,
then PSS is not the appropriate analysis.

From practical point of view, there are many very important meanings in running simulation of "free-running VCO + Mixer" instead of "analogLib/vsource" or "analogLib/port" of fixed frequency.

Here autonomous-PSS with slave PAC, PXF, Pnoise, etc. is very useful if you don't require IP3 evaluation, analysis of frequency pulling by interference signal, etc.
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« Last Edit: Mar 4th, 2010, 3:54am by pancho_hideboo »  
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LeonQQ
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Re: questions about PSS simulation
Reply #4 - Mar 8th, 2010, 9:00am
 
Thank you all for the generous help.

To pancho_hideboo: I am using Cadence for the PSS simulation.
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