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Simulators >> RF Simulators >> questions about PSS simulation
https://designers-guide.org/forum/YaBB.pl?num=1267645148

Message started by LeonQQ on Mar 3^rd, 2010, 11:39am

Title: questions about PSS simulation
Post by LeonQQ on Mar 3^rd, 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

Title: Re: questions about PSS simulation
Post by pancho_hideboo on Mar 3^rd, 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

Title: Re: questions about PSS simulation
Post by sheldon on Mar 3^rd, 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

Title: Re: questions about PSS simulation
Post by pancho_hideboo on Mar 4^th, 2010, 12:24am

sheldon wrote on Mar 3^rd, 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.

Title: Re: questions about PSS simulation
Post by LeonQQ on Mar 8^th, 2010, 9:00am

Thank you all for the generous help.

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