Non-Zero Noise Figure After Calibration
应用文章
The increasing demand for wireless products combined with the availability of modern easy-to-use measurement equipment mean that noise figure measurements are more popular than ever. This is especially true in the microwave region of the spectrum where more and more wireless standards are being developed.
Noise figure measurements rely on a calibrated noise source as a reference. The general measurement process is shown in the figures below. In Figure 1, the noise source is connected directly to the input of the measuring instrument and a user calibration is performed. This measures and stores the instrument’s own noise figure at its various attenuator settings. These results are used to remove the effect of “second-stage” noise contribution during a corrected measurement.