You are appending completely new questions without responding to the following.http://www.designers-guide.org/Forum/YaBB.pl?num=1239925339/1#1From contents of this new questions, you should append this new questions to the following your another post.http://www.designers-guide.org/Forum/YaBB.pl?num=1239389950weigiho wrote on May 4th, 2009, 12:14pm:Actually I found something strange in simulating the NF of a superhetreodyne receiver.
It is not strange at all.
weigiho wrote on May 4th, 2009, 12:14pm:My RF=1.021GHz, LO1=1GHz, IF1=21GHz, LO2=20GHz, and baseband=1MHz.
These are typos ?
Correctly they are
IF1=21MHz and
LO2=20MHz. Right ?
Yes. Thanks for your correction.
Show me netlist for "PORT0". Do you set type of "PORT0" as "dc" or "sine" ?
PORT0 (net0181 0) port r=50 type=dc ampl=1u freq=1.021G fundname="F1" \
fundname2="F2"
I set it to dc.
I think you do two tones large signal(LO1=1000MHz, LO2=20MHz) steady state analysis because your fundamental frequency of PSS is 20MHz.
Is this correct ?
Yes. You are right!
Nodes, "Out+" and "Out-" are open loaded ?
If "Out+" and "Out-" are terminated by some resistor, turn off noise of them by setting temperature -273.15degC.
They are opened.
weigiho wrote on May 4th, 2009, 12:14pm:1.The way I applied the input is shown in the attached file.
I am not sure whether I should use egain=+/- 0.5 or +/-1 for RF input, but I use +/-1 anyway.
There are no difference about NF evaluation even if you choose egain=+/- 0.5 or +/-1.
When I try +/-0.5, I got SSB_NF=18.59dB, the ASB_NF=10*log(1/0.0653)=11.82dB at 1MHz. Both are different from using +/-1. It seems to me that it matters.
weigiho wrote on May 4th, 2009, 12:14pm:2.The input of the mixer is not matched to 50 ohm.
3.The output of the mixer is not matched to 50 ohm.
You don't have to care about these at all.
http://www.designers-guide.org/Forum/YaBB.pl?num=1237656418weigiho wrote on May 4th, 2009, 12:14pm:4.When I use results-->direct plot-->mainform-->......to plot the NF,
it shows NF=13.34dB at 1MHz.
This NF value is conventional SSB NF.
weigiho wrote on May 4th, 2009, 12:14pm:5.When I use results-->print-->noise summary, I got something in the following
Device Param Noise Contribution % Of Total
/PORT0 rn 2.39115e-10 21.84
/N8 id 1.38898e-10 12.69
/N4 id 1.38898e-10 12.69
Spot Noise Summary (in V^2/Hz) at 1M Hz Sorted By Noise Contributors
I calculate the NF=10*log(1/0.2184)=6.6075dB. Is this right?
Right.
But this NF value is DSB NF of Agilent ADS's definition, which is called as ASB_NF(All SideBand NF) to distinguish it from conventional DSB NF.
See
http://www.designers-guide.org/Forum/YaBB.pl?num=1162399761Agilent Simulators such as ADSsim and GoldenGate give following three NF.
- SSB_NF(Conventional SSB NF)
- DSB_NF(Conventional DSB NF)
- ASB_NF(All SideBand NF, DSB NF of Agilent ADS's definition)
Actual NF meter such as Agilent N8975A Noise Figure Analyzer gives ASB_NF, neither SSB_NF nor DSB_NF.
weigiho wrote on May 4th, 2009, 12:14pm:Why these 2 results are different?
This is because there are many spurious receiving frequencies in your RX System.
LO1=1000MHz, IF1=21MHz, LO2=20MHz, IF2=1MHz
At least, there are following remarkable spurious receiving frequencies in your RX System.
(1) Primary Image Frequency for IF1 ; 979MHz
(2) Primary Image Frequency for IF2 ; 981MHz and 1019MHz
(3) Half IF Image Frequency for IF1 ; 989.5MHz and 1010.5MHz
(4) Half IF Image Frequency for IF2 ; 990.5MHz and 1009.5MHz
If your spurious receiving frequencies in your RX System are only (1) and (2), SSB_NF-ASB_NF is lesser than 6dB.
But if there are many receiving frequencies in your RX System other than (1) and (2), SSB_NF-ASB_NF could be larger than 6dB like your case.
In your case, SSB_NF=13.34dB, ASB_NF=6.607dB, SSB_NF-ASB_NF=6.733dB>6dB
Confirm your spurious receiving frequencies by using PSS/PXF or QPSS/QPXF and show me results.
I will check it. Thanks.
weigiho wrote on May 4th, 2009, 12:14pm:should I correctly give the input to the superhytereodyne receiver?
See my appends in
http://www.designers-guide.org/Forum/YaBB.pl?num=1208883935weigiho wrote on May 4th, 2009, 12:14pm:Is the egain=1 correct?
Correct. Any value except for 0 is OK.
weigiho wrote on May 4th, 2009, 12:14pm:Do I have to put 2 seperate ports as input?
No, you don't have to do.
weigiho wrote on May 4th, 2009, 12:14pm:Does input/output matching matter?
No, it doesn't matter.
weigiho wrote on May 4th, 2009, 12:14pm:I really have no idea. Can you kindly help me with this?
I'm not kind and patient enough for explaining such too basic issues.
If you can not still understand, other people who is very kind and patient will help you.