Jose L. Agraz, PhD

Electronic Noise

All electronic circuits show some type of noise. This noise is produced by three random factors: 1) The motion of electrons in a material, 2) the motion of holes and electrons in a semiconductor, and 3) the diffusion of holes and electrons in a potential barrier. These random type of motion lead to three of the most notable types of noise: 1) Thermal noise, 2) Shot noise, 3) Flicker noise (1/f)

Thermal Noise

Thermal noise is generated by the thermal energy causing free electrons to travel randomly through a material. This type of noise was first found by Schottky and measured by Johnson and later an open circuit model published by Nyquist given by equation (1). This type of noise is also known as white noise, as thermal noise has a flat power distribution in the optical band. Thermal noise between f₁ and f₂ is simply given by equation (2)