Enter the bandwidth, temperature, and resistor value into the calculator to determine the thermal noise. This calculator helps in understanding the noise generated in electrical circuits due to thermal agitation.
Thermal Noise Formula
The following formula is used to calculate the thermal noise (in volts squared):
Vn² = 4 * k * T * B * R
Variables:
- Vn² is the thermal noise power in volts squared (V²)
- k is the Boltzmann constant (1.380649e-23 J/K)
- T is the absolute temperature in Kelvin (K)
- B is the bandwidth in Hertz (Hz)
- R is the resistor value in Ohms (Ω)
To calculate the thermal noise, multiply the Boltzmann constant by the absolute temperature, bandwidth, and resistor value.
What is Thermal Noise?
Thermal noise, also known as Johnson-Nyquist noise, is the electronic noise generated by the thermal agitation of charge carriers (usually electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied voltage. Thermal noise is a fundamental limitation in the sensitivity of electronic equipment and is directly proportional to the temperature and bandwidth of the system.
How to Calculate Thermal Noise?
The following steps outline how to calculate the thermal noise:
- First, determine the bandwidth (B) of the system in Hertz (Hz).
- Next, determine the absolute temperature (T) of the resistor in Kelvin (K).
- Next, determine the resistor value (R) in Ohms (Ω).
- Use the formula Vn² = 4 * k * T * B * R to calculate the thermal noise power.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Bandwidth (B) = 1000 Hz
Temperature (T) = 300 Kelvin
Resistor Value (R) = 1000 Ohms
