ABSTRACT
Noise is generated in all semiconductor devices. The intensity of these fluctuations depends on device type, its manufacturing process, and operating conditions. Thermal noise is created by random motion of charge carriers due to thermal excitation. This noise is sometimes known as the Johnson noise. In 1905, Einstein presented his theory of fluctuating movement of charges in thermal equilibrium. This theory was experimentally verified by Johnson in 1928. The thermal motion of carriers creates a fluctuating voltage on the terminals of each resistive element. Shot noise is associated with a discrete structure of electricity and the individual carrier injection through the pn junction. In each forward-biased junction, there is a potential barrier that can be overcome by the carriers with higher thermal energy. Generation-recombination noise is caused by the fluctuation of number of carriers due to existence of the generation-recombination centers.
