How to Measure Noise Figure Using the Y-Factor Method

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Signal Analyzer
+ Signal Analyzer
Signal Analyzer
+ Signal Analyzer

Characterizing noise figure measurements using a signal analyzer

Measuring noise figure requires characterizing a receiver and its ability to detect weak incoming signals in the presence of self-generated noise. Engineers achieve this by measuring signal-to-noise ratio (SNR) degradation as a signal passes through a system or device. They assess the relative amount of noise introduced during the signal's journey. This measurement process requires a test setup comprising a noise source, the device under test (DUT), and a signal analyzer equipped with a noise figure measurement application.

The noise source generates a known noise power level, serving as a reference, and then feeds it into the DUT. It entails two states: "on" and "off." In the "on" state, the DUT usually operates with an input signal, and measurements of both the signal and noise are taken. The Y-factor calculates the ratio of noise to signal power. In the "off" state, the system bypasses the DUT and only measures the noise. The analyzer calculates the Y-factor once more — comparing these Y-factors determines the noise figure.

Noise figure measurement solution

Deploying the right Y-factor measurement technique to determine the noise figure requires a signal analyzer and noise source. The Keysight MXA signal analyzer provides a wide frequency range of 10 Hz to 50 GHz with up to 160 MHz analysis bandwidth. Adding the noise figure measurement application, which is installable in the signal analyzer, enables one-button noise figure and gain measurements. Pairing a USB-powered smart noise source reduces set up time with more automation.
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