NF and Gain Measurement using SA & Noise Source - RF Cafe Forums
Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.
Below are all of the forum threads, including all the responses to the original posts.
Post subject: NF and Gain Measurement using SA & Noise Source
Unread postPosted: Sun Jul 11, 2004 5:38 pm
Please help me to Measure LNA NF & Gain using Spectrum Analyzer & Noise Source
Unread postPosted: Tue Jul 13, 2004 12:51 pm
Joined: Sun Aug 03, 2003 2:02 pm
Location: Erie, PA
Agilent has an application note for that here:
Spectrum Analyzer Measurements and Noise
Application Note 1303
http://cp.literature.agilent.com/litweb ... -4008E.pdf
- Kirt Blattenberger :smt024
Post subject: Using Noise generator for NF measurement
Unread postPosted: Tue Dec 14, 2004 9:30 pm
Sorry the Agilent app note referenced in the other reply will not help you .
see instead /5952-3706E.pdf.
You need to set your spec. an. to work as a RF power meter.
1. Set IF bandwidth high as you dare.
2. Set Video filter as low as you have time to wait for trace.
3. Set to 1 dB/ div or if youre lucky use a maker at the centre of your noise.
4. You will need a low noise preamp if the gain of your device or system (DUT) is gain is less than about 20dB.
5. Check for this - the noise level should drop by at least 10dB when you disconnect or power down your DUT.
6. If not use minicircuits or other gain block amplifier to get result 5.
super low noise not required about 4dB is OK.
7. Connect noise generator to DUT. switch on, your spec an noise should jump at least 3dB.
8. Apply Y factor formula to calculate result from generator ENR, ambient temp (ussually assumed), and change in spec. an. dB reading noise generator off to on. Y is this dB reading converted to a straight power ratio
9. Y factor method formulas are on the net see /5952-3706E.pdf