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Simulators >> RF Simulators >> Issues about IIP3 measurement in cadence
https://designers-guide.org/forum/YaBB.pl?num=1413177425

Message started by VINAY RAO on Oct 12^th, 2014, 10:17pm

Title: Issues about IIP3 measurement in cadence
Post by VINAY RAO on Oct 12^th, 2014, 10:17pm

I am finding out IIP3 points using PSS and PAC analysis. But the problem is I am getting different IIP3 points for different input power levels. Center frequency for my LNA is 5.5 GHz, I am following these steps to simulate IIP3 performance.

1. First setting PSS: Two tones are considered to be separated for 50 MHz (besides, on what basis two tone separation is decided? ). So I selected my beat frequency as 50 MHz. Accordingly, selected array of indices are 90 100 110 and 111.

2.PAC setting: Single point input frequency is set at 5.55 GHZ i.e. is f2. Maximum sideband is selected as 3. PAC magnitude is set to -50dbm bcz 1-dB compression point resulted is -13dB.

3.Plotting IIP3: Single input power value is set to -50 dBm. 1st order harmonic f1 as 5.5 GHz and 3rd order harmonic 2f1-f2= 4.5 GHz.

When I plot these, I am getting IIP3 of -1.82 dBm.

I ran same thing for PAC magnitude of -40 dBm. Now 1 dB compression point remained same but IIP3 point shifted to +3 dBm.

Am I doing wrong in any of above steps? How to find the exact IIP3 point?

Regards,
Vinay