Use the following guidelines for noise figure (NF) measurement:
- As Figure 3-3 shows, the traditional Y-factor method can be used for the NF measurement using a noise diode and a spectrum analyzer (or a noise figure analyzer).
- While doing the measurement, take into account any RF cable losses to the EVM board. Any external input attenuator added for matching results in proportional NF degradation and must be calibrated out in the measurement.
- Also, onboard losses of the input traces at the device input pin must be factored into the NF measurement.
- If the loss after the device output is significant, factoring the output loss into the NF measurement is important. Use the Friis equation to calculate the NF of the device from the total measured NF.