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Simulators >> RF Simulators >> QPSS does not work with IQ_demodulator from rlib
https://designers-guide.org/forum/YaBB.pl?num=1177436129

Message started by Bill Toole on Apr 24^th, 2007, 10:35am

Title: QPSS does not work with IQ_demodulator from rlib
Post by Bill Toole on Apr 24^th, 2007, 10:35am

Hi

I do not understand why QPSS does not work with IQ_demodulator (or MIXER_PB) in the rflib but works in PSS. I get the error message

Error found by spectre during Quasi-Periodic Steady State Analysis `qpss'.
Fundamental name F1 given in parameter `funds' is either not associated with any fundamental name specified in input sources, or not unique

It appears to expect an actual external source like a port or vsin for the LO instead of an internal source as in the mixer component
Furthermore if I replace MIXER_PB with mixer and osc (also from the rflib) it works fine but the osc does not need an actual source. The code for the osc is very similar to LO portion in IQ_demodulator (or Mixer_PB). So why does it work in one but not the other? I would rather use IQ_demodulator for image rejection modeling purposes. Suggestions?

Bill

Title: Re: QPSS does not work with IQ_demodulator from rl
Post by Jess Chen on Apr 25^th, 2007, 4:30pm

Did you include in your schematic a separate independent signal source with frequency equal to the internal frequency of the demodulator? If so, did you give that independent source a name? Although you can specify the frequency of the internal LO, there is no way to give it a name that SpectreRF can access. Consequently, you must include in your schematic a named source with the proper frequency. It sounds like perhaps your QPSS analysis has one more frequency than your PSS analysis and that frequency is associated with the internal demodulator LO.

-Jess

Title: Re: QPSS does not work with IQ_demodulator from rl
Post by Bill Toole on Apr 26^th, 2007, 6:33am

No I did not have an independent signal source with the frequency set to the frequency of the internal source. I had no independent signal source at all except the rf input. It worked fine for a two tone PSS sim. I had to manually add the LO tone in the PSS setup window and it worked but wouldn't for QPSS. However, I have since added an independent source with the frequency set to the frequency of the internal source and it worked fine in both PSS and QPSS. Thanks good idea.