This work deals with the study of the ‘‘trapping noise,’’ that is the low frequency noise caused by the random capture and release of carriers by localized traps. A numerical method, based on the linearization of the semiconductor device equations, is presented which allows one to determine the parameters of the Lorentzian noise spectrum due to a single trap inside a semiconductor device as a function of the position of the trap, of its activation energy and of the biasing conditions. The occupied trap is simulated by adding a single ionized shallow acceptor at the position of the trap. The method allows one to also determine the spectral density of the noise due to a general distribution of noninteracting traps inside the considered device. Numerical tests on elementary semiconductor devices are included to validate the proposed scheme and the trapping noise is then studied on a simple junction field effect transistor. ©1995 American Institute of Physics.