Influence of Cable Losses in Gain and Noise Figure Measurement on a Spectrum Analyzer

When measuring the gain and noise figure on a spectrum analyzer, the device being tested is typically connected to the noise source and measuring equipment using coaxial waveguides and adaptors, which introduce some losses that affect the measurement results. It is particularly important for measurements carried out on chips of integrated circuits as part of a wafer, when it is necessary to use microwave probes, coaxial cables, and various connectors to connect the studied object to the measuring system. In this study, the influence of losses in connections on the results of measuring the gain and noise figure on a spectrum analyzer using the Y-factor method is analyzed. It is demonstrated that the measured value of the gain figure of the studied object is less than the real value by the sum of the losses in the connections between the noise source with the object and the object with the spectrum analyzer. It is established that the noise figure is independent of the losses between the studied object and the measuring device, and the measured value is greater than the real value by the connection losses between the source of the noise and the object.