Where to use Gamma optimum value in LNA?

[ceg]

In LNA Design Gamma optimum value is given? pls tell me where to use this Gamma optimum value is it for input or output matching of the amplifier.

Gamma optimum value is for maximum gain or for low noise figure.

And also pls tell me where can i use conjugate matching.

 

[vfone]

gamma optimum

In LNA design the optimal Input Return Loss (to get max gain) can be achieved only when the input-matching network terminates the device with a conjugate of S11, which in many cases is different from the conjugate of Gamma Optimum (for low noise figure).
Gamma optimum is to get the low noise figure and is given by the manufacturer together with S parameter file in this format: Gamma opt (Mag Ang)

 

[ceg]

understanding gamma optimum

thank u for explaining,
Let me put in my way of understanding.

So, to get max gain input matching network should be conjugate match of s11 of the device.
And to get Low noise figure value my input matching network should be conjugate match of gamm optimum(mag,Ang).

ami correctly understood or not?
pls

 

[vfone]

lna gamma

Yes, you are correct

 

[radiohead]

lna; max gain

I think there is a minor flaw: for optimum noise performance the reflection coefficient (Gamma) of the transformed source impedance should be equal to the optimum noise reflection coefficient (Gamma_opt) and not its conjugate.