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Simulators >> Circuit Simulators >> IP3:How to choose extrapolation point?
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Message started by chingkailun on Dec 25^th, 2004, 7:08am

Title: IP3:How to choose extrapolation point?
Post by chingkailun on Dec 25^th, 2004, 7:08am

Dear all,

I am designing 40MHz Gm-C bandpass filter(0.18u tech) using Cadence Spectra.

I have problem in choosing value for Input Power Extrapolation Point (dBm) when plotting IP3? I get different value for IP3 with different Input Power Extrapolation Point value. What does it mean? I am doing PSS analysis.

How do I know which value of IP3 that is correct?
Is there any rule of thumb?

Plz help..I am new to Cadence...
Thanks!

Kailun

Title: Re: IP3:How to choose extrapolation point?
Post by Amorn on Feb 22^nd, 2005, 12:46pm

Dear Kailun,

Select the extrapolated point within the +3dB/dB slope area of your IM3 curve (the same slope as 3dB/dB guide line), normally it is in the low power area. Choosing any point within this area will result in similar IP3.

Otherwise, using PAC analysis as describe in "Accurate and rapid measurement of IP2 and IP3" could help.

Regards,
Amorn