in band iip3

Hi all,

In the following article a 5GHz WLAN receiver has been implemented with the following parameters (last page):

IIP3=-2dBm
LNA Gain = 18dBm

and in the article it is mentioned that the receiver can support blockers of up to -11dBm.
let assume that we have a blocker of -20dBm then:

PIM3,block = Pout,block - 2*(IIP3 - Pin,block) = -2dBm - 2*(-2 + 20) = -38dBm.

(Pout,block - PIM3,block= 36dB )

so the IM3 due to the blocker is at magnitude of -38dBm.

If the input signal is at sensitivity of say -60dBm.

then -> Pout = Pin + G = -60dBm + 18dB = -42dBm.

so the IM3 due to the blocker is higher! at 4dB then the desired output power.

How can it be? how does the article justifies itself that it supports the Hiperlan2 and 802.11a ?!

as far as I know, the blocker signal rejection is most critical in the sensitivity region where the signal may be weak and blocker may be so strong (40dB higher then the signal) such that the IM3 due to the blocker is higher then the desired output.

I will appriciate your answer and thanks in advance.

i will measure my dut immediately,i'll see my result ,comparing with your question.