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https://designers-guide.org/forum/YaBB.pl Simulators >> RF Simulators >> Mixer NF with swept LO simulation problem https://designers-guide.org/forum/YaBB.pl?num=1090451801 Message started by Rehan Zakai on Jul 21st, 2004, 4:16pm |
Title: Mixer NF with swept LO simulation problem Post by Rehan Zakai on Jul 21st, 2004, 4:16pm I am working on a direct conversion mixer and I need to plot NF at a fixed baseband frequency as a function of swept LO frequency. Does anyone know how QPSS and QPNOISE analyses should be setup? I have tried to setup LO frequency as a swept design variable for QPSS analysis and performed a single point QPNOISE analysis but that does not produce correct results. Is there anything I have to do out of the ordinary when setting up the analysis? Thank you in advance. R. Zakai |
Title: Re: Mixer NF with swept LO simulation problem Post by August West on Jul 22nd, 2004, 8:44am I don't have any suggestions on how to sweep the LO frequency, but it strikes me that these two analyses are overkill in this situation. If you want the NF with only the LO applied, you should be able to use PSS and PNoise. -August |
Title: Re: Mixer NF with swept LO simulation problem Post by Rehan Zakai on Jul 22nd, 2004, 9:03am Since this a narrow band direct conversion mixer, the beat frequency for PSS analysis is too small practically. QPSS analysis is better suited to handle these types of circuits. My understanding is when beat frequency for PSS analysis is less than 1/10 of the LO frequency, QPSS is more practical solution. R. Zakai |
Title: Re: Mixer NF with swept LO simulation problem Post by August West on Jul 22nd, 2004, 9:32pm But you don't have a beat, at least in a large-signal sense. The only large signal applied is the LO, so you can use PSS & PNoise. -August |
Title: Re: Mixer NF with swept LO simulation problem Post by Rehan Zakai on Jul 29th, 2004, 9:19am Just to close on this issue, QPSS analaysis is the only thing to do here, there is a beat, it is equal to the LO frequency and since it varies as LO frequency is swept, PSS analysis does not work. QPSS is easy to setup, I originally has problems due to a scripqting error elsewhere. Rehan |
Title: Re: Mixer NF with swept LO simulation problem Post by August West on Jul 29th, 2004, 10:37am To get a beat you need two large tones. Clearly the LO is one large tone. But what is the other? If there is only one large tone, then PSS should work. -August |
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