A new model to semiconductor device electronic noise is presented in the framework of semiclassical transport theory. The salient feature of this model is that it connects the current noise characteristics directly to the physics of scattering of the semiclassical transport theory and makes no additional assumption regarding the nature of noise. Employing this approach, this work investigates the spatial origin of the current noise across two semiconductor structures. In this approach the terminal current noise is directly related to carrier scattering inside the device, which is accounted for in the Boltzmann transport equation (BTE), without the need to add Langevin noise terms to the calculations. Accordingly, it utilizes the well-established spherical harmonics expansion (SHE) technique to solve the BTE, and it combines analytical and numerical methods, in contrast with the Monte Carlo (MC) approach that employs ensemble averages of randomly generated events. The model leads to the solution of a time-dependent transient solution of the BTE with special initial and Ohmic boundary conditions that is solved in the frequency domain to directly compute the terminal current noise spectral density. It is also shown that with this approach the Nyquist theorem under thermal equilibrium conditions is recovered. (C) 2010 Elsevier Ltd. All rights reserved.