which is the correct matching path in LNA?

[John_li]

hi all,
I want to matching LNA for the noise,assume the Gamma(opt)=0.13/124.48,there is two matching path:from 50 Ohm to Zopt,or Zopt to 50 Ohm.In my mind,it is the different topology.and the last one is convenient and accurate to operate in smithchart.But more ducument select the first.Which one i should select?Why?
Thank you,

 

[khouly]

if ur matching from 50 ohm to Zopt , then the 50 ohm side will be the antenn and Zopt will face the device and so on

i think they both wil work , but it will depend on how u will implement it . the avalibale components , and so on

khouly

 

[VSWR]

There is a good Amplifier Design Tutorial here which includes a noise matching procedure, I have used it several times:

**broken link removed**

 

[Rainleo]

When you are talking about Gamma,opt, that must be Gamma,s, which related to source impedance, so the correct way is to match from 50Ohm to Gamma,opt. However, you can to it in the other way, but you have to match from conj(Gamma,opt) to 50Ohm