Thermal Noise Power
Noise power is based on the thermal noise power at the input of the system, along with system gain and noise
figure:
,
where
![Noise power equation formula constants - RF Cafe](images2/thermal-noise-equation-constants.gif)
![Thermal noise power (dBW) - RF Cafe](images2/thermal-noise-power-dbw-equation.gif)
Multiply by 1000 to obtain milliwatts and then convert to dBm units:
or, factoring out the 1000:
Now that we have the thermal noise at the input, add the system gain and the additional noise added by the system
(the NF) to get the noise power at the output:
Thermal Noise Voltage
![Thermal noise voltage equation - RF Cafe](images2/thermal-noise-voltage-equation.gif)
![Thermal Noise Voltage as a Function of Resistance and Bandwidth - RF Cafe](images/thermal_noise_voltage_bandwidth_resistance.gif)
Related Pages on RF Cafe -
Noise Figure <--> Noise Temperature
Calculator - Noise Power and Voltage -
Cascaded Noise Figure -
Noise Figure Meters & Noise Generators -
Noise Sources
"Noise
and Interference" - WebEE Tutorial
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