This paper outlines the charge-based core and the model architecture of the BSIM5, an advanced charge-based MOSFET model for nanoscale VLSI circuit simulation. Compared with the previous charge-based models with an assumption of the linearization of the bulk and inversion charges with respect to the surface potential at a fixed gate bias, the BSIM5 model is directly derived from the solution of the Poisson equation coupled to the current density equation. The comparisons of the inversion charge and the channel current between the BSIM5 and the Pao-Sah model indicate that the BSIM5 model maintains the inherent device physics and high accuracy of the Pao-Sah model. BSIM5 model is further extended to include the short-channel effects, narrow-width-effects, and the wide comparison with the experiment data demonstrates its validity to Simulate the nanoscale circuits. Moreover, the symmetry and RF function of BSIM5 have also been demonstrated in the Gummel tests and high-order distortion analysis. (C) 2007 Elsevier Ltd. All rights reserved.