Noise figure of LNA
Depends on the application. Noise figures of 0.5 dB is quite normal for S band.
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
Just for information here is a recent Agilent selection guide with a lot of transistors showing 0.5 dB NF for 2 GHz
It's depends from the expected receive power level,antenna gain and other,but 0.8 - 1dB will be enough.
Someone has some information about gsm system? Thanks for answer!
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
the nf of GSM RX is about 2dB.
say about 5-7dB
bye mrm
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"