A new analytical model for the current–voltage characteristic of a resonant tunneling diode (RTD) is presented herein, being derived from the basic integral of the Tsu–Esaki equation. The model is physics based and developed as a function of material parameters such as the effective mass, barrier heights, and Fermi levels as well as geometrical parameters such as the barrier height and well width. The material chosen for the double-barrier RTD structure is AlGaAs/GaAs. The dependence of the peak transmission on the applied voltage and the scattering effect in the active region, which are neglected in previous models, are also taken into account. The model is implemented and validated using numerical simulations, revealing that the resulting electrical characteristic is in good agreement with numerical simulations using the Green’s function formalism.