a doubt about RF Impedance matching

In GSM RF system , usually We will use SAW then add a PI Impedance matching network to realize power match
For example, The transceiver's LNA input Impedance is 150 OHM(Differential)
we usually use a SAW with a PI matching network to conncet the LNA input
(SAW 50 OHM to 150 OHM)
I want to know , the SAW output is 150 ohm and the Transceiver's LNA input port is also 150 ohm why we need the pi network to Impedance matching?

"I want to know , the SAW output is 150 ohm and the Transceiver's LNA input port is also 150 ohm why we need the pi network to Impedance matching?
"

May be I misunderstand your question...

If is RX path may be that is matched in a optimal S/N ratio instead optimal power transfer, the two defined impedances are tipically diferent.

What's the type of the SAW, still single-ended or differential? If it is single-ended, then the impedance network may play a role as a balun.

The 150 ohms LNA input impedance is a theoretically resistive impedance. In reality is a complex impedance tens/hundreds of ohms in parallel with few pF. The matching network it will match this complex impedance with the impedance of the SAW filter for minimum in-band ripple, best LNA Gain and NF, maximum rejection, etc.

i agree with vfone , due to paasictics in packages the impedance are not pure real , so u need some matching circuits , for optimum performance

khouly

thanks
the product SAW of murata's impedance are not pure real , i know the reason of the matching.
thanks for all of your help