Convert between Noise Figure and Noise Temperature by entering your Noise Figure (in dB), Reference Temperature (in Kelvin), and selecting your Conversion Type — the Noise Temperature Calculator gives you the Converted Value alongside the Noise Factor, Equivalent Noise Temperature, and Noise Figure (Linear).
Converted Value
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Noise Factor
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Equivalent Noise Temperature
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Noise Figure (Linear)
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Noise figure (NF) is the ratio of signal-to-noise ratio at the input to that at the output, expressed in dB. Noise temperature (Te) represents the equivalent temperature that would produce the same thermal noise power. They're related by: NF(dB) = 10×log10(1 + Te/T0), where T0 is reference temperature (290K).
For RF amplifiers, noise figures typically range from 0.5-3 dB for excellent performance, 3-6 dB for good performance, and above 6 dB for basic applications. Low noise amplifiers (LNAs) in sensitive receivers aim for under 1 dB noise figure.
290K (approximately 17°C or 62°F) is the IEEE standard reference temperature for noise measurements. It represents typical room temperature conditions and provides a consistent baseline for comparing noise performance across different systems and manufacturers.
Lower noise temperature indicates better system sensitivity. A 100K reduction in noise temperature can improve receiver sensitivity by approximately 1.5 dB, which significantly impacts the ability to detect weak signals in communication and radar systems.
Noise factor (F) is the linear ratio of input SNR to output SNR. Noise figure (NF) is the same ratio expressed in decibels: NF(dB) = 10×log10(F). Noise factor is always ≥1, while noise figure is always ≥0 dB.
Noise figure is typically measured using a noise figure meter with a calibrated noise source. The Y-factor method is common, where measurements are taken with the noise source on and off, and the ratio determines the noise figure.
No, absolute noise temperature cannot be negative as it represents physical thermal noise. However, effective noise temperature in some active devices (like masers) can appear negative, indicating gain rather than loss in the noise analysis.
Noise figure generally increases with frequency due to various factors including transistor limitations, parasitic elements, and thermal effects. Each amplifier has a specified frequency range where its noise performance is characterized.