narrow bandwidth of LNA for WIMAX

[adnan siddqui]

Noise figure of LNA

What should be the Noise Figure of the LNA used in satellite Data receiver at LEO.The frequency band is S.

 

[g579]

Re: Noise figure of LNA

Depends on the application. Noise figures of 0.5 dB is quite normal for S band.

 

[mrm]

Re: Noise figure of LNA

0.5 is very good (probably you're a best designer than I'm). I was able to reach 0.4dB only with cryogenic parametric amplifiers, but it was some years ago.
Bye Mrm

 

[g579]

Re: Noise figure of LNA

Just for information here is a recent Agilent selection guide with a lot of transistors showing 0.5 dB NF for 2 GHz

 

[pva]

It's depends from the expected receive power level,antenna gain and other,but 0.8 - 1dB will be enough.

 

[ucraina]

Someone has some information about gsm system? Thanks for answer!

 

[mrm]

Re: Noise figure of LNA

GSM System has 200KHz bandwith and -104 Receiver sensitivity (static).
Since the S/I is tipically 9dB this yelds a noise figure maximum of 173.8-10*log200E3+cochannel. Usually GSM BS are able to reach a -110 static sensitivity

 

[ttrf]

Re: Noise figure of LNA

the nf of GSM RX is about 2dB.

 

[mrm]

Re: Noise figure of LNA

say about 5-7dB
bye mrm

 

[activewei]

Actually noise figure should be as low as possible. But at S-band receiver chain, the 1st noise contributor is the antena follow by a bandpass filter. The antenna noise is quite high and the noise of the bandpass filter is equal to the insertion of the filter. Though you have very low noise amplifier, the overall noise figure is still high. My conclusion is: "if you can design as low noise figure as possible, thumb up. If noise figure of LNA is greater than 1dB but less than 2.5dB, it is still acceptable in LEO receiver"