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Design >> RF Design >> IP3 graph
https://designers-guide.org/forum/YaBB.pl?num=1108203897

Message started by myjasonlee on Feb 12^th, 2005, 2:24am

Title: IP3 graph
Post by myjasonlee on Feb 12^th, 2005, 2:24am

Hello All

Are there anyone who has experience in plotting IP3 curve for any mixer case? In order to plot IP3 curve, we have to calculate the value of the IM coeeficient right?
such as 3/4.aplha3.A^3(from Dr Rzavi's book)....
I have problems in this topic and urgently need your advice.
Kindly let me know.
Thank you

rgds and thanks
Jason

Title: Re: IP3 graph
Post by Ken Kundert on Feb 12^th, 2005, 12:53pm

Have you read http://www.designers-guide.com/Analysis/intercept-point.pdf.

-Ken

Title: Re: IP3 graph
Post by myjasonlee on Feb 12^th, 2005, 8:37pm

Hi Ken

Thanks a lot for the link. I have seen that before.
It is a more detailed document explaining about IP2 and IP3.
However, I would like to know where and how we are going to get the coefficient for the IM term

See for IP3,

x= a.u + c.u^3

Then may I know how do we get the a and c value?

Kindly enlighthen

Thanks and rgds
Jason

Title: Re: IP3 graph
Post by Ken Kundert on Feb 12^th, 2005, 9:29pm

The gain is a. The value of c can be computed from IP₃ using (29) or (30) from that paper.

-Ken

Title: Re: IP3 graph
Post by myjasonlee on Feb 12^th, 2005, 10:12pm

Dear Ken,

Thank you so much.
That is really helpful.
Actually I am in the midst of finding my IP3 and c value. So one of them must be found before I can evaluate the equation you mention. I will try to plot the graph to see if there is any chance I can find the c value or vice versa.
I will post back here and hope you can help me on this later.
Thank you Ken

rgds and thnaks
Jason