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mixer minimum noise figure simulation (Read 31098 times)
Ian
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Re: mixer minimum noise figure simulation
Reply #15 - Apr 17th, 2008, 7:24am
 
I followed your lead, and I've got perfectly matched results from either pss+pnoise or pss+psp,
no matter one tone or two tones. The accuracy is within 0.005 dB.

pancho_hideboo, many many thanks. Frankly speaking, at the very beginning, I didn't expect
someone could help me in such great detail, but you surely are! I appreciate it very much.
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pancho_hideboo
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Re: mixer minimum noise figure simulation
Reply #16 - Apr 17th, 2008, 8:11am
 
Ian wrote on Apr 17th, 2008, 7:24am:
I followed your lead, and I've got perfectly matched results from either pss+pnoise or pss+psp,
no matter one tone or two tones. The accuracy is within 0.005 dB.

Maybe your RF interference ampl=vrf is very small so it doesn't affect NF characteristics.

Many people often say results of PAC, PXF, Pnoise and PSP don't match.
But they must be always matched. Just your settings are wrong or you don't understand equations used in Direct Plot Form.  :P

After many many corrections. we can be back to your first question.
Now you do correct setting for PSP, do you come to be able to get NFmin and Gmin as meaning value ?


I will not use SpectreRF. Still I don't believe SpectreRF results at all. Cool
http://www.designers-guide.org/Forum/YaBB.pl?num=1205223090
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« Last Edit: Apr 17th, 2008, 6:25pm by pancho_hideboo »  
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Ian
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Re: mixer minimum noise figure simulation
Reply #17 - Apr 21st, 2008, 2:17am
 
[quote author=pancho_hideboo link=1208334972/15#16 date=1208445088] Quote:
After many many corrections. we can be back to your first question.
Now you do correct setting for PSP, do you come to be able to get NFmin and Gmin as meaning value ?


Unfortunately, the 'NFmin' plot is still 'NaN' and Gmin sits at the center of the smith chart. Abosultely meaningless. Lately, I upgraded my spectre to higher version, i.e.,
Version 6.2.0.420 -- 11 Jun 2007, which makes no difference on these results.

Ian
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pancho_hideboo
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Re: mixer minimum noise figure simulation
Reply #18 - Apr 21st, 2008, 2:51am
 
[quote author=Ian link=1208334972/15#17 date=1208769421]pancho_hideboo wrote on Apr 17th, 2008, 8:11am:
Quote:
After many many corrections. we can be back to your first question.
Now you do correct setting for PSP, do you come to be able to get NFmin and Gmin as meaning value ?
Unfortunately, the 'NFmin' plot is still 'NaN' and Gmin sits at the center of the smith chart. Abosultely meaningless. Lately, I upgraded my spectre to higher version, i.e.,
Version 6.2.0.420 -- 11 Jun 2007, which makes no difference on these results.
Ian

Do you realy do set PSP correctly ?

In original netlist, you set like following where it is natural even if you get "NaN" as NFmin.

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
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« Last Edit: Apr 21st, 2008, 7:19am by pancho_hideboo »  
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Ian
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Re: mixer minimum noise figure simulation
Reply #19 - Apr 21st, 2008, 6:41am
 
pancho_hideboo wrote on Apr 21st, 2008, 2:51am:
Do you realy do set PSP correctly ?

In original netlist, you set like following where it is natural even if you get "NaN" as NFmin.

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

Well, this time, I believe, 100% good in settings Wink

PS:

pss  pss  fund=100M  harms=0  errpreset=moderate  maxacfreq=5.5G
+    annotate=status  outputtype=freq  maxiters=15
psp  psp  start=1K  stop=130M  portharmsvec=[-11  0]  ports=[PORT_RF+    PORT_IF]  donoise=yes
+  maxsideband=55  annotate=status  freqaxis=out

PORT_RF (vrf 0) port r=50 num=1 type=sine freq=1G ampl=vrf  fundname="frf"
PORT_LO (vlo 0) port r=50 num=3 type=sine freq=1.1G ampl=vlo fundname="flo"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc

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pancho_hideboo
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Re: mixer minimum noise figure simulation
Reply #20 - Apr 21st, 2008, 7:09am
 
Ian wrote on Apr 21st, 2008, 6:41am:
pss  pss  fund=100M  harms=0  errpreset=moderate  maxacfreq=5.5G
+    annotate=status  outputtype=freq  maxiters=15
psp  psp  start=1K  stop=130M  portharmsvec=[-11  0]  ports=[PORT_RF+    PORT_IF]  donoise=yes
+  maxsideband=55  annotate=status  freqaxis=out

PORT_RF (vrf 0) port r=50 num=1 type=sine freq=1G ampl=vrf  fundname="frf"
PORT_LO (vlo 0) port r=50 num=3 type=sine freq=1.1G ampl=vlo fundname="flo"
PORT_IF (Vloadp Vloadn) port r=50 num=2 type=dc

It seems OK except for typo.

Which method do you use to plot NFmin, Direct Plot Form or Result Browser ?
Try Result Browser.
If both can't work, you should report to Cadence.

SpectreRF have not been used deeply in RF design community, so there could be many bugs.
I don't believe SpectreRF results at all, so I will not use SpectreRF for RF design.
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« Last Edit: Apr 21st, 2008, 5:03pm by pancho_hideboo »  
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Re: mixer minimum noise figure simulation
Reply #21 - Apr 23rd, 2008, 12:12am
 
Comparing PSP's results with Agilent RFDE(ADSsim) and GoldenGate,
I noticed "freqaxis" has to be "absin" when I want to evaluate S-parameters including Gmin(=Sopt) in PSP of SpectreRF.

Setting of "freqaxis" should affect only independent variable of output results.
But it can affect S-parameter value. Maybe this is also bug of SpectreRF.

Quote:
Input port (PORT_RF) frequency range = (-1.1 GHz -> -970 MHz).
Output port (PORT_IF) frequency range = (1 kHz -> 130 MHz).

In PSP of SpectreRF, unless "freqaxis" is "absin", S-parameters are wrongly calculated like following.

  S11=b1(-RF_freq)/a1(-RF_freq)
  S21=b2(IF_freq)/a1(-RF_freq)
  S12=b1(-RF_freq)/a2(IF_freq)
  S22=b2(IF_freq)/a2(IF_freq)

where RF_freq is positive value.

So S11 is wrongly calculated as complex_conjugate of true S11.
S21 and S12 are also wrongly calculated.


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« Last Edit: Apr 23rd, 2008, 5:11pm by pancho_hideboo »  
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Ian
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Re: mixer minimum noise figure simulation
Reply #22 - Apr 25th, 2008, 2:56am
 
[quote author=pancho_hideboo link=1208334972/15#21 date=1208934731] Quote:
So S11 is wrongly calculated as complex_conjugate of true S11.

That explains! I did observe the S11 from PSP is the conjugate of the S11 got from SP.

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new_guy
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Re: mixer minimum noise figure simulation
Reply #23 - Mar 7th, 2010, 10:47pm
 
Hi Pancho,

I followed this post with great intent. Would like to find out if I running spectre simulation for a subharmonic mixer, what would the reference side band should be for spectre PSS PNOISE analysis?

Thanks

Regards
New_guy
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pancho_hideboo
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Re: mixer minimum noise figure simulation
Reply #24 - Mar 8th, 2010, 1:46am
 
new_guy wrote on Mar 7th, 2010, 10:47pm:
Would like to find out if I running spectre simulation for a subharmonic mixer,
what would the reference side band should be for spectre PSS PNOISE analysis?
It is +2 or -2, if you choose 1tone drive where there is no RF interference.

http://en.wikipedia.org/wiki/Subharmonic_mixer

BTW, have you been able to understand the following ?
http://www.designers-guide.org/Forum/YaBB.pl?num=1193135745/6#6
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« Last Edit: Mar 8th, 2010, 3:08am by pancho_hideboo »  
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Re: mixer minimum noise figure simulation
Reply #25 - Mar 9th, 2010, 6:32pm
 
Hi pancho,

Thanks a lot.
However even if the setup is single tone (large signal is LO and RF set to DC), the reference sideband might not be -2 or +2.
-2 or +2 works only if LO and RF are multiples, eg RF = 2.4GHz and LO=1.2GHz.
If RF =2.4GHz  and LO=1.0 GHz, reference sideband would not be -2 or +2, correct?

Thanks



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Re: mixer minimum noise figure simulation
Reply #26 - Mar 10th, 2010, 2:00am
 
new_guy wrote on Mar 9th, 2010, 6:32pm:
However even if the setup is single tone (large signal is LO and RF set to DC), the reference sideband might not be -2 or +2.
-2 or +2 works only if LO and RF are multiples, eg RF = 2.4GHz and LO=1.2GHz.
No.
You are completely misunderstanding.

Again have you been able to understand the following ?
http://www.designers-guide.org/Forum/YaBB.pl?num=1193135745/6#6

new_guy wrote on Mar 9th, 2010, 6:32pm:
If RF =2.4GHz  and LO=1.0 GHz, reference sideband would not be -2 or +2, correct?
Of course, it can not be correct.
No one except for you thinks it is correct.

I assume IF frequency where you observe noise is 0.4GHz.
RF=IF+2*LO, Here RF=2.4GHz, LO=1.0GHz, IF=0.4GHz.
In this case, reference sideband is "+2".

Surely read message of "spectre -h pnoise" as unix command.


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« Last Edit: Mar 11th, 2010, 1:12am by pancho_hideboo »  
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