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Simulators >> RF Simulators >> simulating IIP3 of an N-Path Filter
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Message started by Mahdi3999 on Oct 26^th, 2015, 7:48am

Title: simulating IIP3 of an N-Path Filter
Post by Mahdi3999 on Oct 26^th, 2015, 7:48am

Hi everybody,
I have problems simulating IIP3 of an N-path filter. My bandpass filter is clocked with FLO=1GHz and I define two sines with Freq1=1.15GHz and Freq2=1.3GHz at the input port to simulate IIP3 using qpss analysis. The power of both these sines is PowerRF=-30dBm. I have doubts about choosing the correct "1st Order Harmonic" and "3rd Order Harmonic" under "Direct Plot Form". This form has following options for the 3rd order harmonic
FLO Freq1 Freq2
1GHz 2 -2 1
1GHz 1 0 0
1GHz 0 2 -1

and following options for the 1st harmonic
FLO Freq1 Freq2
1.15GHz 2 -3 2
1.15GHz 1 -1 1
1.15GHz 0 1 0
1.15GHz -1 3 -1

1.3GHz 1 -2 2
1.3GHz 0 0 1
1.3GHz -1 2 0

I think I must choose 0 2 -1 for the 3rd order harmonic and either 0 1 0 (1.15GHz) or 0 0 1 (1.3GHz) for the 1st one, however the result is about +8dBm while in the the reference paper it is +21dBm!!! I cannot find any reason for this difference, I should mention that all the parameters are the same for my simulation and the simulation of the paper.
Interestingly, choosing 0 1 0 for 1.15GHz gives somewhat different results than choosing 0 0 1 for 1.3GHz.
I would appreciate if anybody helps me with this problem.

Title: Re: simulating IIP3 of an N-Path Filter
Post by hoangthithi1993 on Mar 31^st, 2016, 12:33am

For myself, I still don't know how to measure the IIP3 for the N-path filter. Can anyone give me some instructions on this? In the picture is the circuit I set up to measure the IIP3. Is it true?

Thank you very much!