Microwave Low Noise Amplifier operating in the X band

[miz0406]

Hi! I am currently designing a microwave low noise amplifier. for this design i am using atf 34143 rf transistor. I am still in the 1st step of designing the LNA. Using the s2p files of the transistor, the best gain is 5.7dB and NF 2dB at 9GHz. I would like to ask if these values are acceptable. Are the gain and the noise figure going to improve after the dc biasing and input and output matching? by the way, i am usin the ansoft designer.

Thanks!

 

[tony_lth]

I would like to ask if these values are acceptable. Thanks!

It's determined by your specification of LNA. What's your LNA object?

 

[rfmw]

Why don't you try with the x-band hemt, ATF-36077?

 

[miz0406]

i tried ATF 36077..however, it is not stable within the Xband...

is it possible for me to make it unconditionally stable within the xband..when i simulated it using ansoft designer, the gain is high and it has a very low noise figure.. the only problem is that it is unstable within the xband..

 

[jayce3390]

Hi,
Designing LNA at X band with S2P files is not correct, you need a transistor model, I guess you know that. Did you already design a LNA with the ATF 36077 ? A carrefull design should make it unconditionnally stable.

 

[miz0406]

hello. i'm still looking for the dc biasing condition for which the transistor would have the highest gain and the lowest noise figure possible..and i'm also considering the stability of the transistor in the x-band..am i in the right direction?

 

[vfone]

ATF34143 gets good performances only up to 2.5GHz. There are other Avago LNA that works well at 9GHz.
An LNA part of a receiver system should have gain at least 10dB to worth the cost and the design work.

 

[miz0406]

hello. i have this problem in designing the LNA using Ansoft. ATF 36077 does not have its equivalent model in Ansoft library. Also, the datasheet does not have the necessary values available for 9GHz. How can I layout the DC bias circuit without the transistor model?