The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Feb 7th, 2023, 1:34pm
Pages: 1 2 
Send Topic Print
mixer minimum noise figure simulation (Read 29399 times)
Ian
Junior Member
**
Offline



Posts: 27

mixer minimum noise figure simulation
Apr 16th, 2008, 1:36am
 
For LNA, it's common practice to use SP simulation to see the 'Gmin' and 'NFmin' and do the noise matching. Here I want to do the same thing for the mixer.

I tried PSS + PSP for an acitve mixer, the simulated NF was very close to the result predicted by PSS+Pnoise at the bands dominated by thermal noise. However, the 'Gmin' there only gives a result of zero real part and zero imaginary part, and  the 'NFmin' plot is empty. I don't know what's going on there. Any comments? Thanks.

Ian
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #1 - Apr 16th, 2008, 4:12am
 
Ian wrote on Apr 16th, 2008, 1:36am:
For LNA, it's common practice to use SP simulation to see the 'Gmin' and 'NFmin' and do the noise matching. Here I want to do the same thing for the mixer.
I tried PSS + PSP for an acitve mixer, the simulated NF was very close to the result predicted by PSS+Pnoise at the bands dominated by thermal noise.

NF results of PSS/Pnoise and PSS/PSP have to be completely same unless you do wrong setting in simulation.
If your results are not same completely, your setting must be wrong, maybe for PSP.

Quote:
However, the 'Gmin' there only gives a result of zero real part and zero imaginary part, and  the 'NFmin' plot is empty. I don't know what's going on there. Any comments? Thanks.
Ian

I checked NFmin and Gmin in PSS/PSP for mixer using "spectre  version 6.2.0 09/19/2007 14:35 (sfsol77) $".

Both Gmin and NFmin give non zero value although I don't believe SpectreRF results at all.
Since your NFmin is "NaN", your setting of PSP must ne wrong.
PSP(QPSP) setting is relative difficult.

I also confirmed Gmin and NFmin results of Agilent ADS(RFDE).
In RF design, ADS(MDS, Series-IV) have long history and is most reliable.

Spectre's Gmin is same as ADS.
But NFmin of Spectre is apparently suspicious. You must not believe NFmin of Spectre.
PSP and QPSP are not available in HB analysis. They are available only for shooting PSS/QPSS.
As far as I know, PSP and QPSP are not used so much. Especially QPSP is not used and verified, I think.
If they are not fixed, NF(dsb, ssb, ieee-ssb) of QPSP must be still wrong.

But as far as my experience, NFmin and Gmin for mixer analysis are not so valuable even in ADS(RFDE).





Back to top
« Last Edit: Apr 16th, 2008, 8:49am by pancho_hideboo »  

Mixer_NFmin.JPG
View Profile WWW Top+Secret Top+Secret   IP Logged
Ian
Junior Member
**
Offline



Posts: 27

Re: mixer minimum noise figure simulation
Reply #2 - Apr 16th, 2008, 8:08am
 
Thanks, pancho_hideboo. I appreciate your comments and nice plot.    

I reported here some of my progress in the following.

I simulated a conventional Gilbert-cell mixer, the results got from PSS/PSP
and PSS/Pnoise settings were (almost) the same. Then I simulated a modified
version of Gilbert mixer (using current-resue bleeding technique) using both
methods, they coincided well in the flat band, but still not in the 1/f noise region.
I adjusted the automatic sweep in the psp setting to linear sweep (i.e., 100pts),
two curves match better than before (see the attached plot).  

Another interesting obeservation is that at the intended IF frequency
(e.g., 100MHz in the attached plot), there's a spike in the NF curve
generated from PSS/PSP.  

P.S.: my spectre version: $CDS: icfb.exe version 5.1.0 06/30/2005 00:12 (cicln03) $
Back to top
 

GBMixerIbldTIA_NFcomp_psspnoise_vs_psspsp.png
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #3 - Apr 16th, 2008, 8:13am
 
Try Pnoise and PSP with solver=std in option setting.

Show me netlist portions regarding port or source(RF, LO, IF) statement and analysis statement.

Ian wrote on Apr 16th, 2008, 8:08am:
P.S.: my spectre version: $CDS: icfb.exe version 5.1.0 06/30/2005 00:12 (cicln03) $

This is DFII's version not Spectre's version.
Back to top
 
 
View Profile WWW Top+Secret Top+Secret   IP Logged
Ian
Junior Member
**
Offline



Posts: 27

Re: mixer minimum noise figure simulation
Reply #4 - Apr 16th, 2008, 8:52am
 
pancho_hideboo wrote on Apr 16th, 2008, 8:13am:
Show me netlist portions regarding signal source statement and analysis statement.


--- Source Statement
PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo \
       fundname="flo"
PORT_RF (net081 0) port r=Rs_rf num=1 type=sine freq=frf ampl=vrf \
       fundname="frf"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc freq=flo ampl=vlo \
       fundname="flo"

--- Analysis Statement
pss  pss  fund=100M  harms=30  errpreset=moderate  annotate=status
psp  psp  sweeptype=relative  start=-99.999M  stop=30M  lin=100
+    portharmsvec=[-10  1]  ports=[PORT_RF  PORT_IF]  donoise=yes
+    maxsideband=50  annotate=status  freqaxis=out

For the spectre version, funny enough, I couldn't find it out right now.
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #5 - Apr 16th, 2008, 8:58am
 
Ian wrote on Apr 16th, 2008, 8:52am:
For the spectre version, funny enough, I couldn't find it out right now.
You can find it in output log of simulation. Search menu list under Simualtion in ADE.

Ian wrote on Apr 16th, 2008, 8:52am:
--- Source Statement
PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo \
       fundname="flo"
PORT_RF (net081 0) port r=Rs_rf num=1 type=sine freq=frf ampl=vrf \
       fundname="frf"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc freq=flo ampl=vlo \
       fundname="flo"

--- Analysis Statement
pss  pss  fund=100M  harms=30  errpreset=moderate  annotate=status
psp  psp  sweeptype=relative  start=-99.999M  stop=30M  lin=100
+    portharmsvec=[-10  1]  ports=[PORT_RF  PORT_IF]  donoise=yes
+    maxsideband=50  annotate=status  freqaxis=out

Teach me values of flo, frf.
Also teach me options statement.

BTW why do you set freq=flo ampll=vlo fundname="flo" in PORT_IF ?
It is type=dc, though..... So it can be no effect.



Back to top
 
 
View Profile WWW Top+Secret Top+Secret   IP Logged
Ian
Junior Member
**
Offline



Posts: 27

Re: mixer minimum noise figure simulation
Reply #6 - Apr 16th, 2008, 9:08am
 
pancho_hideboo wrote on Apr 16th, 2008, 8:58am:
Ian wrote on Apr 16th, 2008, 8:52am:
For the spectre version, funny enough, I couldn't find it out right now.
You can find it in output log of simulation. Search menu list under Simualtion in ADE.


I guess this is it:
spectre (ver. 5.10.41_USR2.052705 -- 27 May 2005).

Other info:
1. flo=1.1GHz and frf=1GHz.
2. Options Statement as follows:

simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=27 \
   tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
   digits=5 cols=80 pivrel=1e-3 ckptclock=1800 \
   sensfile="../psf/sens.output" checklimitdest=psf
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #7 - Apr 16th, 2008, 9:42am
 
Ian wrote on Apr 16th, 2008, 9:08am:
I guess this is it:
spectre (ver. 5.10.41_USR2.052705 -- 27 May 2005).

You are using fairly old Spectre. HB analysis is not available in your version.
You might be required to do old style accuracy setting for SpectreRF.
Also NFmin and Gmin of PSP in your version's Spectre might be completely broken,
although they are still very suspicious even in relative new version I use.

Show me analysis statement of Pnoise to compare with PSP setting.
Back to top
 
 
View Profile WWW Top+Secret Top+Secret   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #8 - Apr 16th, 2008, 7:48pm
 
If I run PSP on SunOS 5.8 with @(#)$CDS: spectre  version 6.2.0 09/19/2007 14:35 (sfsol77) $,
PSP can't work and gives fatal error.
But If I run PSP on Linux 2.4.21-32.ELsmp, PSP can work.
Anyway PSP and QPSP have not been used and verified so much.

First while you set harms=30 in PSS, you set maxsideband=50 in PSP.
This could give uncorrect results.

Set like following.

simulatorOptions options reltol=1e-5 vabstol=3e-8 iabstol=1e-13 temp=27 \
   tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
   digits=5 cols=80 pivrel=1e-3 sensfile="../psf/sens.output" \
   checklimitdest=psf

pss  pss  fund=100M  harms=0  errpreset=moderate  method=gear2only
+    relref=alllocal  maxacfreq=6G  annotate=status  outputtype=freq
+    maxiters=15

pnoise  pnoise  start=1k  stop=130M  dec=11  maxsideband=50
+       oprobe=PORT_IF  iprobe=PORT_RF  refsideband=-11  annotate=status

psp  psp  start=1k  stop=130M  dec=11  portharmsvec=[-11  0]
+    ports=[PORT_RF  PORT_IF]  donoise=yes  maxsideband=50  annotate=status
+    freqaxis=out


Maybe there are wrong settings also in your Pnoise.
Show me your Pnoise statement.

If your setting is proper, you can see the following message in log file.

****************************************************    
Periodic Steady-State Analysis `pss': fund = 100 MHz
****************************************************    

***********************************************************
Periodic Noise Analysis `pnoise': freq = (1 kHz -> 130 MHz)
***********************************************************
Input frequency range = (970 MHz -> 1.1 GHz).
Using the operating-point information generated by PSS analysis `pss'.


********************************************************************
Periodic S-Parameter Analysis `psp': sweep freq = (1 kHz -> 130 MHz)
********************************************************************
Input port (PORT_RF) frequency range = (-1.1 GHz -> -970 MHz).
Output port (PORT_IF) frequency range = (1 kHz -> 130 MHz).
Using the operating-point information generated by PSS analysis `pss'.
Back to top
 
« Last Edit: Apr 16th, 2008, 11:59pm by pancho_hideboo »  
View Profile WWW Top+Secret Top+Secret   IP Logged
Ian
Junior Member
**
Offline



Posts: 27

Re: mixer minimum noise figure simulation
Reply #9 - Apr 17th, 2008, 12:07am
 
pancho_hideboo wrote on Apr 16th, 2008, 7:48pm:
Quote:
First while you set harms=30 in PSS, you set maxsideband=50 in PSP.
This could give uncorrect results.

That's exactly the manual "SpectreRF Simulation Option User Guide (June 2004, Version 5.1.41)"
tells me to do.

Quote:
pss  pss  fund=100M  harms=0  errpreset=moderate  method=gear2only
+    relref=alllocal  maxacfreq=6G  annotate=status  outputtype=freq
+    maxiters=15


so you set PSS fundamental as IF frequency, instead of both LO and RF
also recommended in the previously mentioned spectre manual. Then in the
schematic, which port should be set as IF frequency, LO or RF? And
I guess the other one has to be set as DC, otherwise it would be
automatically show up in the PSS fundamentals.

Quote:
Maybe there are wrong settings also in Pnoise.
Show me Pnoise statement.

Please be patient, right now my license server is down.
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #10 - Apr 17th, 2008, 12:13am
 
Ian wrote on Apr 17th, 2008, 12:07am:
pancho_hideboo wrote on Apr 16th, 2008, 7:48pm:
First while you set harms=30 in PSS, you set maxsideband=50 in PSP.
This could give uncorrect results.

That's exactly the manual "SpectreRF Simulation Option User Guide (June 2004, Version 5.1.41)"
tells me to do.

It is not appropriate. There are many mistakes or wrong explanations in SpectreRF manual.
But maybe it is not problem since maxstep is very small in PSS even though you set harms=30.

Real problems exist in your setting of Pnoise and PSP.
Show me log file.

Quote:
pss  pss  fund=100M  harms=0  errpreset=moderate  method=gear2only
+    relref=alllocal  maxacfreq=6G  annotate=status  outputtype=freq
+    maxiters=15
so you set PSS fundamental as IF frequency, instead of both LO and RF
also recommended in the previously mentioned spectre manual. Then in the
schematic, which port should be set as IF frequency, LO or RF? And
I guess the other one has to be set as DC, otherwise it would be
automatically show up in the PSS fundamentals.

You don't understand PSS.

100MHz is not IF frequency.
This is fundamental frequency determined by flo and frf.

I set harms=0  maxacfreq=6G in PSS.  

Port settings are following. These are yours.

PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo \
fundname="flo"
PORT_RF (net081 0) port r=Rs_rf num=1 type=sine freq=frf ampl=vrf \
fundname="frf"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc freq=flo ampl=vlo \
fundname="flo"


Quote:
Please be patient, right now my license server is down.

Even if license server is down, you can see netlist and log file in unix tree unless you delete them.

Do you need two large signal truely ?
See http://www.designers-guide.org/Forum/YaBB.pl?num=1184111670
Back to top
 
« Last Edit: Apr 17th, 2008, 9:47am by pancho_hideboo »  
View Profile WWW Top+Secret Top+Secret   IP Logged
Ian
Junior Member
**
Offline



Posts: 27

Re: mixer minimum noise figure simulation
Reply #11 - Apr 17th, 2008, 12:54am
 
My PSS+Pnoise settings:

pss  pss  fund=1.1G  harms=0  errpreset=moderate  method=gear2only
+    relref=alllocal  maxacfreq=6G  annotate=status  outputtype=freq
+    maxiters=15
pnoise  pnoise  start=1K  stop=130M  dec=11  maxsideband=50
+       oprobe=PORT_IF  iprobe=PORT_RF  refsideband=-1  annotate=status

In PSS+Pnoise, fund=1.1GHz, however, in the PSS+PSP simulation, you are right. fund=100MHz.
That's why I got confusion earlier.

Another comment is that I used the newly pnoise settings, the result (use auto-sweep) still deviates
from the one got from psp simulation at 1/f noise region, as in my previous attached plot.

Quote:
Do you need two large signal truely ?
See http://www.designers-guide.org/Forum/YaBB.pl?num=1184111670


I understand for the pnoise simulation, rf port set as dc. For psp simulation,
if so, then fund=1.1GHz (no more intended 100MHz when frf=1GHz). I doubt
the psp settings you gave to me earlier, particularly 'portharmsvec=[-11 0].
Now the equivalent frf became -12.1G  -- -11.97G.

I even tried just set flo=100MHz, and use your psp settings exactly, the resulting
NF is way too big, around 30dB larger.
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #12 - Apr 17th, 2008, 1:00am
 
Ian wrote on Apr 17th, 2008, 12:54am:
My PSS+Pnoise settings:
pss  pss  fund=1.1G  harms=0  errpreset=moderate  method=gear2only
+    relref=alllocal  maxacfreq=6G  annotate=status  outputtype=freq
+    maxiters=15
pnoise  pnoise  start=1K  stop=130M  dec=11  maxsideband=50
+       oprobe=PORT_IF  iprobe=PORT_RF  refsideband=-1  annotate=status

The above is different from following.
Also do you understand meaning of harms=0  maxacfreq=6G in PSS ?
Show me original netlist of PSS/Pnoise and PSS/PSP where you observe difference of results between them.
Show me original log file of PSS/Pnoise and PSS/PSP.


What do you want to do ?
Do you want to do PSS/Pnoise and PSS/PSP under two large signal drive ?
And you want to know why PSS/Pnoise and PSS/PSP results don't match ?


Ian wrote on Apr 16th, 2008, 8:52am:
pancho_hideboo wrote on Apr 16th, 2008, 8:13am:
Show me netlist portions regarding signal source statement and analysis statement.

--- Source Statement
PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo \
       fundname="flo"
PORT_RF (net081 0) port r=Rs_rf num=1 type=sine freq=frf ampl=vrf \
       fundname="frf"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc freq=flo ampl=vlo \
       fundname="flo"

--- Analysis Statement
pss  pss  fund=100M  harms=30  errpreset=moderate  annotate=status
psp  psp  sweeptype=relative  start=-99.999M  stop=30M  lin=100
+    portharmsvec=[-10  1]  ports=[PORT_RF  PORT_IF]  donoise=yes
+    maxsideband=50  annotate=status  freqaxis=out
For the spectre version, funny enough, I couldn't find it out right now.


Back to top
 
 
View Profile WWW Top+Secret Top+Secret   IP Logged
Ian
Junior Member
**
Offline



Posts: 27

Re: mixer minimum noise figure simulation
Reply #13 - Apr 17th, 2008, 2:00am
 
Quote:
What do you want to do ?
Do you want to do PSS/Pnoise and PSS/PSP under two large signal drive ?
And you want to know why PSS/Pnoise and PSS/PSP results don't match ?


Well, of coz, I want to have matched results between PSS/Pnoise and PSS/PSP.
That's why I adapted my settings to yours to try to get it.

To remind you, the intended flo=1.1GHz and frf=1GHz. Teach me what's 'maxacfreq=6G'?

-- Original Log Message for PSS+Pnoise:

****************************************************      
Periodic Steady-State Analysis `pss': fund = 1.1 GHz
****************************************************      

***********************************************************
Periodic Noise Analysis `pnoise': freq = (1 kHz -> 130 MHz)
***********************************************************
Input frequency range = (970 MHz -> 1.1 GHz).
Using the operating-point information generated by PSS analysis `pss'.

-- Original Log Message for PSS+PSP:

****************************************************      
Periodic Steady-State Analysis `pss': fund = 100 MHz
****************************************************  

********************************************************************
Periodic S-Parameter Analysis `psp': sweep freq = (1 kHz -> 130 MHz)
********************************************************************
Input port (PORT_RF) frequency range = (-1.1 GHz -> -970 MHz).
Output port (PORT_IF) frequency range = (1 kHz -> 130 MHz).
Using the operating-point information generated by PSS analysis `pss'.

Original Netlist Options for PSS+Pnoise:
pss  pss  fund=1.1G  harms=0  errpreset=moderate  annotate=status
pnoise  pnoise  start=1K  stop=130M  dec=20  maxsideband=50
+       oprobe=PORT_IF  iprobe=PORT_RF  refsideband=-1  annotate=status

PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo \
       fundname="flo"
PORT_RF (net081 0) port r=Rs_rf num=1 type=dc
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc

Original Netlist Options for PSS+PSP:
pss  pss  fund=100M  harms=30  errpreset=moderate  annotate=status
psp  psp  sweeptype=relative  start=-99.999M  stop=30M  lin=100
+    portharmsvec=[-10  1]  ports=[PORT_RF  PORT_IF]  donoise=yes
+    maxsideband=50  annotate=status  freqaxis=out

PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo \
       fundname="flo"
PORT_RF (net081 0) port r=Rs_rf num=1 type=sine freq=frf ampl=vrf \
       fundname="frf"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: mixer minimum noise figure simulation
Reply #14 - Apr 17th, 2008, 2:19am
 
Quote:
Original Netlist Options for PSS+Pnoise:
pss  pss  fund=1.1G  harms=0  errpreset=moderate  annotate=status
pnoise  pnoise  start=1K  stop=130M  dec=20  maxsideband=50
+ oprobe=PORT_IF  iprobe=PORT_RF  refsideband=-1  annotate=status

fund=1.1G, maxsideband=50
So maximum frequency of noise folding is fund*maxsideband=55GHz

Quote:
Original Netlist Options for PSS+PSP:
pss  pss  fund=100M  harms=30  errpreset=moderate  annotate=status
psp  psp  sweeptype=relative  start=-99.999M  stop=30M  lin=100
+    portharmsvec=[-10  1]  ports=[PORT_RF  PORT_IF]  donoise=yes
+    maxsideband=50  annotate=status  freqaxis=out

fund=100M, maxsideband=50
So maximum frequency of noise folding is fund*maxsideband=5GHz

In addition to difference of 1tone drive and 2tone drive, maximum noise folding frequency is different in your setting for Pnoise and PSP.


If you want to simulate NF of mixer, you have to choose 1tone(only LO) drive or multitone drive(LO and RF).
See http://www.designers-guide.org/Forum/YaBB.pl?num=1184111670

Here assume flo=1100MHz, frf_interference=1000MHz and fif=1kHz~130MHz.
frf_desire will be flo-fif or flo+fif. Then you chose frf_desire=flo-fif, LSB Mixer.

If you choose 1tone drive where there is no RF interference,
PSS/Pnoise/PSP setting has to be like following.

PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo fundname="FLO"
PORT_RF (net081 0) port r=Rs_rf num=1 type=dc
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc

pss  pss  fund=1.1G  harms=0  maxacfreq=5.5G  errpreset=moderate annotate=status  outputtype=freq

pnoise  pnoise  start=1k  stop=130M  dec=11  maxsideband=5
+    iprobe=PORT_RF  oprobe=PORT_IF  refsideband=-1  annotate=status

psp  psp  start=1k  stop=130M  dec=11  maxsideband=5
+    ports=[PORT_RF  PORT_IF]  portharmsvec=[-1 0]  donoise=yes   annotate=status
+    freqaxis=out


If you choose 2tone drive where LO and RF(interference) are large,
PSS/Pnoise/PSP setting has to be like following.

PORT_LO (_net0 0) port r=50 num=3 type=sine freq=flo ampl=vlo fundname="FLO"  
PORT_RF (net081 0) port r=Rs_rf num=1 type=sine freq=frf_interference ampl=vrf fundname="FRF"  
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc

pss  pss  fund=100M  harms=0  maxacfreq=5.5G  errpreset=moderate  annotate=status  outputtype=freq

pnoise  pnoise  start=1k  stop=130M  dec=11  maxsideband=55
+    iprobe=PORT_RF  oprobe=PORT_IF  refsideband=-11  annotate=status

psp  psp  start=1k  stop=130M  dec=11  maxsideband=55
+    ports=[PORT_RF  PORT_IF]  portharmsvec=[-11 0]  donoise=yes   annotate=status
+    freqaxis=out


In relative old SpectreRF, "errpreset=moderate" in pss setting is not helpful.
Instead of this, tighten accuracy parameters.

(1) Add  the followings to pss setting
       method=gear2only relref=alllocal maxiters=15
(2) Set accuracy parameter in options statement like following.
      reltol=1e-5 vabstol=3e-8 iabstol=1e-13 options

Current SpectreRF don't need both (1) and (2).

"harms=0" in pss setting mean we don't save large signal harmonics.
"maxacfreq=5.5G" in pss setting mean maximum frequency for small signal analysis such as pac, pxf, pnoise and psp.
Here I chose it as 5.5GHz=5*flo. maxacfreq has to be larger than 5.5GHz. So maxacfreq=6G is also OK.

In shooting PSS, "maxstep" is very important parameter.
Generally it is determined by "fund" and "harms".
But if your fundamental frequency is very small, this is very inefficient in memoy usage.
So you had better use "maxacfreq".
And in small signal analysis such as NF analysis, we don't need to observe large signal harmonics.
So I set  "harms=0".
Back to top
 
« Last Edit: Apr 17th, 2008, 7:53pm by pancho_hideboo »  
View Profile WWW Top+Secret Top+Secret   IP Logged
Pages: 1 2 
Send Topic Print
Copyright 2002-2023 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.