In a cascode topology the noise introduced by the cascode device (upper transistor added to improve stability of the amplifier) it will be additional to the initial noise.
So, a cascode always will get higher noise figure than a single device (or at least very close).
The pHEMT ATF-38143 from Avago has one of the lowest NF on the commercial market, but has higher NF than you are looking for.
So, do you mean that I need to sacrifice the upper transistor to get better noise? Change to a new topology?
What topology you can recommend?
Or, is there any other possible way without changing the topology?
vfone said:
In a cascode topology the noise introduced by the cascode device (upper transistor added to improve stability of the amplifier) it will be additional to the initial noise.
So, a cascode always will get higher noise figure than a single device (or at least very close).
The pHEMT ATF-38143 from Avago has one of the lowest NF on the commercial market, but has higher NF than you are looking for.
I see...
Besides this method? Any more?
Besides make the transistor smaller and tune the input match, any other techniques to reduce the noise?
Or is there any technical paper can recommended?
Abhishekabs said:
For 0.25dB NF NEC transistors are good, but at this frequency & 0.2dB NF it is hard. you may need to make superconducting LNA
What is your application? specifications?
Speaking of only 0.2dB NF LNA is Vague.
Rather you may get a PhD if you design 0.2 dB NF LNA. for your frequency.
It is not easy.
NF= KTΔF
Here K is constant, so reduce T or ΔF that is bandwidth to get low NF.