Ian wrote on Apr 22nd, 2008, 10:05am:pss pss fund=10M harms=0 errpreset=moderate annotate=status
+ outputtype=freq
You forget to set "maxacfreq" in PSS.
For example, you have to set
maxacfreq=6G.
Ian wrote on Apr 22nd, 2008, 10:05am:pnoise pnoise start=1K stop=1M maxsideband=120
+ oprobe=PORT_IF iprobe=PORT_RF refsideband=-1 annotate=status
"maxsideband=120" is too small. Your fund is 10MHz and flo1=1100MHz, for example, you must set maxsideband more than 5*flo1/fund=550.
So you should set
maxsideband=550.Ian wrote on Apr 22nd, 2008, 11:31pm:ACWWong wrote on Apr 22nd, 2008, 2:21pm:looks like your pnoise reference sideband is wrong. the output log at the start of the pnoise normally prints at what frequency the input port (PORT_RF) has been swept to get the output. In your case it won't be around 1GHz which is what you want...
Indeed, the input frequency in the log is 99MHz to 99.999MHz (i.e., for 1K - 1MHz IF), which is the input frequency of the second mixer.
You are wrong. If you want to evaluate SSB-NF and conversion gain, you have to choose the input frequency of the first mixer.
If you want to evaluate only DSB-NF and not conversion gain, you can set any value as refsideband.
Try to use "select from list" in refsideband setting of Pnoise setting.
In your case, you have to set
refsideband=-101, where first mixer is LSB and second mixer is USB.
1000=abs(10-101*Fund) <--- refsideband=-101, First Mixer In=1000MHz, Second Mixer In=100MHz, Out_freq=10MHz, Fund=10MHz
1020=abs(10+101*Fund) <--- refsideband=101, First Mixer In=1020MHz, Second Mixer In=80MHz, Out_freq=10MHz, Fund=10MHz
Ian wrote on Apr 22nd, 2008, 11:31pm:ACWWong wrote on Apr 22nd, 2008, 2:21pm:There are a couple of other things I would recommend
1) PORT_RF should be dc not sine if you are not looking for noise figure in the presence of a large input RF tone.
I did experiments on both cases, either dc or sine, for one single mixer. They agrees with each other perfectly (though the RF tone is not really a large signal).
But yes, for dc PORT_RF, the simulation could probably be faster. For LO frequencies (also RF frequency) with common divisor (e.g., 100MHz), dc PORT_RF wins sine PORT_RF by about 10s (i.e., 49.43s vs 59.95s).
You should not use unnecessary tones in RF analysis especially in multitone HB-analysis.
It could result in not only slowness in simulation but also wrong results. Also it could not be converged in simulation.
Again see
http://www.designers-guide.org/Forum/YaBB.pl?num=1184111670Ian wrote on Apr 22nd, 2008, 11:31pm:ACWWong wrote on Apr 22nd, 2008, 2:21pm:2) making flo1 and flo2 integer related by a higher common divisor will speed up simulation. (e.g, 1.1G & 100M or 1.08G & 90M etc.
Good point. My first few attempts really took long time for 'random' LO frequencies.
You can also invoke multitone HB analysis such as QPSS. Rather I will use multitone HB analysis for such receiver.
I will not use PSS(Shooting and HB) for double super receiver, indeed I will not use SpectreRF itself for RF design.
In QPSS, you must not set flo1 and flo2 with integer relation.
Also see
http://www.designers-guide.org/Forum/YaBB.pl?num=1162399761