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Simulators >> RF Simulators >> Problem with the mixer simulation
https://designers-guide.org/forum/YaBB.pl?num=1336315502

Message started by harryhu on May 6^th, 2012, 7:45am

Title: Problem with the mixer simulation
Post by harryhu on May 6^th, 2012, 7:45am

Hello.

I am simulating a basic Gilbert downconverter, using PSS, PAC and PNoise. When I change the resistive load to be a first-order RC filtering load, I find that the simulated in-band gain drops and the simulated in-band noise figure increases. And there is no problem with the first-order filtering function and the filtering corner in the simulation results. How to explain this phenomena, or is there any possible problem with the simulation settings for this case?

Thank you.

Title: Re: Problem with the mixer simulation
Post by purplewolf on May 7^th, 2012, 7:13am

whats the performance without the Capacitor? Use only Resistive load and check

Title: Re: Problem with the mixer simulation
Post by harryhu on May 7^th, 2012, 7:39am

There is no problem when using sole resistive load. After adding the parallel capacitors without any other modification, the performance degrades as mentioned earlier.

Title: Re: Problem with the mixer simulation
Post by ACWWong on May 10^th, 2012, 8:50pm

has adding the output capacitor changed the LO slew or amplitude ? It will have change the output "sum" mixing product. is your output capacitor added common mode or differential mode ?
Anyway check the pss solution to see the delta in the steady state on the LO and output ports, both single-ended and differential, in both cases (with and without cap). Then you should see why your pnoise and pac give different results.