Y-Factor
Understanding Y-Factor
The Y-factor is the ratio of output noise power with the noise source on (hot) to the output noise power with the noise source off (cold): Y = N_hot / N_cold. From this ratio and the known ENR (Excess Noise Ratio) of the noise source, the noise figure is calculated.
| Amplifier Type | Noise Figure | Gain | Output Power |
|---|---|---|---|
| LNA | 0.3-2 dB | 10-25 dB | -10 to +10 dBm |
| Driver | 3-8 dB | 10-20 dB | +15 to +25 dBm |
| Power Amp | N/A | 8-15 dB | +30 to +50 dBm |
| Distributed | 3-6 dB | 5-12 dB | +10 to +20 dBm |
NF = ENR / (Y-1) in linear terms, or NF(dB) = ENR(dB) - 10*log10(Y-1). This method is the standard technique for measuring noise figure of amplifiers, mixers, and receivers using a noise figure meter or analyzer.
Frequently Asked Questions
What equipment is needed for Y-factor measurement?
A calibrated noise source with known ENR, a noise figure analyzer or spectrum analyzer, and appropriate cables and adapters for the frequency range.
What are sources of error in Y-factor measurements?
Noise source ENR calibration accuracy, mismatch between components, instrument noise floor, and temperature variations are the primary error sources.