MATLAB Examples

Explicitly Simulate Resistor Thermal Noise

Use the Noise block to calculate the classic thermal noise floor, kT, for a matched resistor circuit. Model configuration is as follows:

  • Time step of the model is 1e-6 and frequency is 2 GHz.
  • The Resistor noise source is modelled explicitly to make it noiseless. The resistance is 50 ohms. In the Resistor blocks, Simulate Noise is not selected.
  • Noise current source parallel to the Resistor block models the noise. In the Noise block, the Source type is set to Ideal current to make it a current source. The Noise spectral density is defined as (4kT/R)(A2/Hz). The value of k is * The Masked block, Calculate Noise Power, calculates the noise floor as a standard deviation of the output signal.

To run the model, select Simulation > Run. With the bandwidth included using the Configuration block, noise power is in the range of -173.98 to 174.1 dBm