This calculator determines the thermal noise power generated in a system as a function of temperature and bandwidth. It is essential for evaluating receiver performance and understanding the fundamental limits of noise in RF and electronic systems.
Useful for RF engineers, receiver designers, communications technicians and students wishing to estimate noise power in dBm over temperature and bandwidth.
Formula
Pn = 10 × log10( (k × B × T) / (1 mW) )
Constants
- k = 1.38064852 × 10⁻²³ (Boltzmann constant)
- 1 mW = 1 × 10⁻³ W
Units
- Temperature: Kelvin (K) or Celsius (°C)
- Bandwidth: Hz, kHz, MHz, GHz
- Result: dBm
Explanation of the formula
- Thermal noise comes from the random agitation of electrons at a given temperature.
- The noise power is proportional to the absolute temperature (T) and the bandwidth (B).
- The logarithm transforms power into dBm for easy comparison with signal levels.
Calculation of thermal noise for 290 K and 1 MHz
Input : T = 290 K, B = 1 MHz
Output : Pn ≈ -114 dBm
Benefits and uses
- Evaluates noise limits in RF receivers and communications systems.
- Helps compare noise levels with signals useful for SNR calculation.
- Useful for designing low noise amplifiers (LNA).
- Essential analysis tool for telecommunications engineers and researchers.