noise units

[Leiser]

Hi all,

I have to measure the noise of an antenna buffer. The datasheet specifies the noise Un=1.5nV/sqrt(Hz) (square root of Hz)

I am used to measure noise voltage in dBm/Hz. Does any one know how can I measure the noise in the unit specified in the datasheet using a sprectum analyzer?

Could anyone explain me this why to define the noise?

Thanks.

 

[VEBill]

Google 'Noise Figure', 'Noise Factor', and 'Noise Temperature' (three searches, one by one).

If this is for your automotive antenna project, keep in mind that noise figure is more critical for the FM Broadcast band than the AM Broadcast band. This is because the external environment sets the noise floor for the lower frequencies.

The overall noise floor is normally set by the first stage. So if this 'antenna buffer' is downstream from an earlier LNA, then its noise level may be less important (by the ratio of the gain of the first stage).

For the FM band, noise figures of a few dB would probably be good enough. State-of-the-art for VHF comms is well under one dB (like 0.2dB NF for example). Dynamic range may be much more critical for this application.