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Anritsu FAQs

Can I use a MS272XB spectrum analyzer to measure noise figure?
Yes, with limitations. A spectrum analyzer can be used to measure the noise figure of a device with a significant amount of gain. The basic method is to start by measuring the noise floor of the instrument with a termination on the input. It is best to do this with attenuation set to 0 dB and the preamplifier turned on with a high averaging value (say, 100 or more). Turn on a marker along with a delta marker and set the marker type to FIXED. Next, connect the ampifier to be measured to the spectrum analyzer's input and move the termination to the input of the amplifier. Restart averaging and wait for the averaging to complete. The delta marker value will be the noise figure of the DUT plus the spectrum analyzer's noise figure divided by the gain of the amplifier. This method isn't suitable for low gain devices because of the "second stage contribution" of the spectrum analyzer.