Two ways to measure noise figure

Reducing receiver-contributed noise may be the least expensive route to take but may also be the most difficult for the designer who must develop a low-noise amplifier at the front end of the receiver. For those designers, an accurate and repeatable method for measuring noise figure (NF) will be a necessity.

Noise figure provides us with a design parameter that describes the amount of additive noise contributed by a system or device under test. Noise can degrade the bit and frame error rates of digital communication systems. In radar systems, receiver noise will limit the effective range of the radar. Naturally, the designer's goal is to optimize the overall signal-to-noise ratio (SNR) to provide the best system performance possible. Noise figure is simply the noise factor (F) expressed in decibels [NF = 10 x log (F)] where F = (Si/Ni)/(So/No), the ratio of the SNR at the input to the SNR at the output.

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