We propose a new implementation of the third-level charge pumping technique for a precise determination of the energy distributions of electron and hole cross sections and interface state density in metal-oxide-semiconductor field-effect transistors (MOSFETs). Using an arbitrary function generator with a high clock rate and a sufficient storage memory length, it is possible to evaluate interface trap emission times and interface state densities in small geometry MOSFETs with a high-energy resolution. The accuracy of the technique has been greatly increased owing to the high stability and the weak distortion of the signal applied to the gate of the device (numerically generating via a high-speed digital-to-analog converter) and the development of a new acquisition procedure. To illustrate the performance of this method, we present the first results concerning the characterization of 0.6 mum N-channel MOSFETs.