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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> How to calculate the out band of IIP3 in communication system? https://designers-guide.org/forum/YaBB.pl?num=1252560761 Message started by spring on Sep 9th, 2009, 10:32pm |
Title: How to calculate the out band of IIP3 in communication system? Post by spring on Sep 9th, 2009, 10:32pm Hi, everyone, In communication system, when there are blocks in N+2 channel and N+4 channel, how to calculate the out band of IIP3, I read a paper"A direct-conversion receiver for DVB-H" it says IIP3=(2Pd+Pa+G-IMD3)/2, I do not know how this formula derived, any one can give me some analysis. thank you:) spring |
Title: Re: How to calculate the out band of IIP3 in communication system? Post by aaron_do on Sep 16th, 2009, 5:16am Hi, first I assume you are trying to calculate the required IIP3, not the IIP3 of some circuit block. You don't need the blockers to be in the N+2 and N+4 channel, N+1 and N+2 will do. The 3rd order output will be y3 = Bx3 10log(y3) = 30log(x) + 10logB the first order is y1 = Ax 10log(y1) = 10log(x) + 10log(A) From here its pretty straight forward. IIP3 is the value of x where y1 and y3 are equal. The gain is of course equal to 10log(A). you can substitute the powers in the N+1 and N+2 channels in y3. cheers, Aaron |
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