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Design >> RF Design >> IIP2 using Monte Carlo
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Message started by Frank Ke on Sep 1^st, 2005, 2:53pm

Title: IIP2 using Monte Carlo
Post by Frank Ke on Sep 1^st, 2005, 2:53pm

For a zero-IF double-balanced mixer, is transient analysis with Monte Carlo the only valid way to simulate for IIP2? Can QPSS/Monte Carlo be used in this situation? IF the IIP2 is around 50dBm, what's the appropriate tolarance control(reltol, vabstol, iabstol)? Thank you.

Title: Re: IIP2 using Monte Carlo
Post by Mighty Mouse on Sep 2^nd, 2005, 12:17am

Have you tried the rapid IP2 approach documented in http://www.designers-guide.org/Analysis/intercept-point.pdf?

It seems like that would probably work for you with default tolerances.

- MM -

Title: Re: IIP2 using Monte Carlo
Post by Frank Ke on Sep 2^nd, 2005, 11:12am

Thanks for the reply. I do have that document with me. Are you referring to the equation IIP2=Pin+(Pout_fundamental - IM2) as the rapid solution?

Title: Re: IIP2 using Monte Carlo
Post by Mighty Mouse on Sep 2^nd, 2005, 11:23am

See section 5.3.

- MM -

Title: Re: IIP2 using Monte Carlo
Post by boshiouke on Sep 2^nd, 2005, 3:18pm

Thanks again for the reply. The problem I have is, when I use 2 tones @ RF port with same power level, their respective output amplitude is quite different due to the low-pass cutoff @ mixer output load. For example, the output fundamental tone@10MHz(P1) is higher than the one at 19MHz(P2) in amplitude. Since IM3 in this case will be at 1MHz, I should calculater delta using 19MHz and 1MHz according to Section 5.3. Keep in mind that this result will be different from if I use 10MHz/1MHz delta. Which one is correct then?

Thank you.

Title: Re: IIP2 using Monte Carlo
Post by boshiouke on Sep 2^nd, 2005, 5:05pm

Mighty Mouse wrote on Sep 2^nd, 2005, 12:17am:

Have you tried the rapid IP2 approach documented in http://www.designers-guide.org/Analysis/intercept-point.pdf?

It seems like that would probably work for you with default tolerances.

- MM -

As I simulate IP2, I get different result when reltol=1e-4(54dBm), 1e-5(77dBm), 1e-6(98dBm), 1e-7(77dBm), 5e-8(87dBm), while vabstol=1e-7 and iabstol=1e-12. I didn't run into this situation with IP3, probably because IM3>>IM2. What do you suggest? Thank you.