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Ian

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Re: mixer minimum noise figure simulation
Reply #15 - Apr 17^th, 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 17^th, 2008, 8:11am

Ian wrote on Apr 17^th, 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 17^th, 2008, 6:25pm by pancho_hideboo »

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Ian

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Re: mixer minimum noise figure simulation
Reply #17 - Apr 21^st, 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 21^st, 2008, 2:51am

[quote author=Ian link=1208334972/15#17 date=1208769421]pancho_hideboo wrote on Apr 17^th, 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 21^st, 2008, 7:19am by pancho_hideboo »

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Ian

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Re: mixer minimum noise figure simulation
Reply #19 - Apr 21^st, 2008, 6:41am

pancho_hideboo wrote on Apr 21^st, 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 21^st, 2008, 7:09am

Ian wrote on Apr 21^st, 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 21^st, 2008, 5:03pm by pancho_hideboo »

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pancho_hideboo

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Re: mixer minimum noise figure simulation
Reply #21 - Apr 23^rd, 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 23^rd, 2008, 5:11pm by pancho_hideboo »

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Ian Junior Member Offline Posts: 27	Re: mixer minimum noise figure simulation Reply #22 - Apr 25^th, 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 Junior Member Offline Posts: 10	Re: mixer minimum noise figure simulation Reply #23 - Mar 7^th, 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 8^th, 2010, 1:46am

new_guy wrote on Mar 7^th, 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 8^th, 2010, 3:08am by pancho_hideboo »

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new_guy

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Re: mixer minimum noise figure simulation
Reply #25 - Mar 9^th, 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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pancho_hideboo

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Re: mixer minimum noise figure simulation
Reply #26 - Mar 10^th, 2010, 2:00am

new_guy wrote on Mar 9^th, 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 9^th, 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 11^th, 2010, 1:12am by pancho_hideboo »

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