The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Simulators >> RF Simulators >> PSTB Analysis with a conversion frequency
https://designers-guide.org/forum/YaBB.pl?num=1217939784

Message started by Realf on Aug 5^th, 2008, 5:36am

Title: PSTB Analysis with a conversion frequency
Post by Realf on Aug 5^th, 2008, 5:36am

Hi all,
I have a problem with PSTB analysis.

I'm designing a VCO ( 6GHZ) with an Automatic Loop Gain.

I hoped to get Gain and Phase by means PSTB + PSS , but I got very strange results.

Is it possible to use PSTB+PSS analysis when there is a conversion frequency ( ALC--> High freq to Low freq)?

I want to highlight that from transient, PSS and Golden Gate Monte Carlo(1000 runs) analysis would seem ALC worked well.

Best Regards
Raffaele

Title: Re: PSTB Analysis with a conversion frequency
Post by pancho_hideboo on Aug 5^th, 2008, 5:57am

Realf wrote on Aug 5^th, 2008, 5:36am:

I'm designing a VCO ( 6GHZ) with an Automatic Loop Gain.

What do you mean by "Automatic Loop Gain" ?
Do you mean ALC, Automatic Level Control ?
So correctly, you mean "VCO(6GHz) with ALC" ?

Realf wrote on Aug 5^th, 2008, 5:36am:

I hoped to get Gain and Phase by means PSTB + PSS , but I got very strange results.

What is strange ? Explain in detail with result's graph.
Show me your netlist regarding signal(power) sources and PSS/PSTB statement.

Realf wrote on Aug 5^th, 2008, 5:36am:

Is it possible to use PSTB+PSS analysis when there is a conversion frequency ( ALC--> High freq to Low freq)?

What do you mean by "ALC--> High freq to Low freq" ?
Also What do you mean by "a conversion frequency" ?
Any mixer or frequency divider is included in your circuit ?
Do you intend to express PLL not ALC ?
If so, is there any fixed frequency source for reference ?

Realf wrote on Aug 5^th, 2008, 5:36am:

I want to highlight that from transient, PSS and Golden Gate Monte Carlo(1000 runs) analysis would seem ALC worked well.

Although we can't do small signal analysis in Agilent GoldenGate autonomous HB analysis, we can do small signal analysis in Agilent RFDE(ADS) autonomous HB analysis. So you can evaluate loop gain using RFDE(ADS).

Title: Re: PSTB Analysis with a conversion frequency
Post by Realf on Aug 5^th, 2008, 7:29am

Hi pancho_hideboo,
I apologize. I realized that my mex was too much brief.

- Yes, I meant ALC with a peak detector.

- In attach you can see the PSTB results,
where is the static gain? :)

-My netlist:

pss ( OUTP VSS ) pss flexbalance=yes oversamplefactor=1
+ fund=6.2e9 harms=40 errpreset=moderate tstab=50n method=gear2only
+ tstabmethod=gear2only annotate=status
pstb pstb start=100 stop=100e6 dec=10 probe=I17.V6 annotate=status

-I spoke about the achieved conversion frequency by means the peak detector.

- I don't know very well RFDE(ADS), could you explain me how I can evaluate the loop gain using it?
What is the analysis?

Thanks in advance
Raffaele

Title: Re: PSTB Analysis with a conversion frequency
Post by pancho_hideboo on Aug 10^th, 2008, 6:51pm

Realf wrote on Aug 5^th, 2008, 7:29am:

- Yes, I meant ALC with a peak detector.

I assume your output level of VCO is controled by VGA after VCO. Is this correct ?

Realf wrote on Aug 5^th, 2008, 7:29am:

pss ( OUTP VSS ) pss flexbalance=yes oversamplefactor=1
+ fund=6.2e9 harms=40 errpreset=moderate tstab=50n method=gear2only
+ tstabmethod=gear2only annotate=status
pstb pstb start=100 stop=100e6 dec=10 probe=I17.V6 annotate=status

Where do you insert probe ?
If you use PSTB of Cadence Spectre, you should insert probe just before a control input of VGA.

Realf wrote on Aug 5^th, 2008, 7:29am:

- In attach you can see the PSTB results,
where is the static gain? :)

I can't understand your question.

Realf wrote on Aug 5^th, 2008, 7:29am:

- I don't know very well RFDE(ADS), could you explain me how I can evaluate the loop gain using it?
What is the analysis?

Since you evaluate loop gain of zero side band signal, you can use PSTB of Cadence Spectre.