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stevie-g
Joined: 15 Oct 2009
Posts: 8
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 05 Nov 2009 13:20 Anyone can get 0.2dB NF for cascode LNA? |
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Hey guys,
I'm looking for any cascode CS-LNA circuit design which can get 0.2dB NF at 2.5GHz in simulation.
Do you have it?
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vfone
Joined: 10 Oct 2001
Posts: 2328
Helped: 327
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05 Nov 2009 17:28 Re: Anyone can get 0.2dB NF for cascode LNA? |
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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.
http://www.avagotech.com/docs/AV02-1443EN
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stevie-g
Joined: 15 Oct 2009
Posts: 8
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06 Nov 2009 2:38 Re: Anyone can get 0.2dB NF for cascode LNA? |
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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 wrote: |
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.
http://www.avagotech.com/docs/AV02-1443EN |
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Abhishekabs
Joined: 12 Jan 2007
Posts: 727
Helped: 84
Location: India
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06 Nov 2009 6:42 Anyone can get 0.2dB NF for cascode LNA? |
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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
Added after 51 seconds:
I mean you need to use cooling techniques.
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stevie-g
Joined: 15 Oct 2009
Posts: 8
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06 Nov 2009 11:21 Re: Anyone can get 0.2dB NF for cascode LNA? |
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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 wrote: |
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
Added after 51 seconds:
I mean you need to use cooling techniques. |
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Abhishekabs
Joined: 12 Jan 2007
Posts: 727
Helped: 84
Location: India
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06 Nov 2009 11:29 Re: Anyone can get 0.2dB NF for cascode LNA? |
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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.
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stevie-g
Joined: 15 Oct 2009
Posts: 8
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06 Nov 2009 11:38 Re: Anyone can get 0.2dB NF for cascode LNA? |
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Ya... I know it's a bit tough.
I thought there got any new topology I don't know.
Anyway, thanks man!
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06 Nov 2009 11:38 Ads |
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tomhive
Joined: 26 May 2006
Posts: 36
Helped: 1
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21 Nov 2009 7:47 Re: Anyone can get 0.2dB NF for cascode LNA? |
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| stevie-g wrote: |
Ya... I know it's a bit tough.
I thought there got any new topology I don't know.
Anyway, thanks man! |
What is the BW you are looking for.You can use SPF3143 it has lowest noise figure.
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