This paper presents a new wideband modeling technique to exactly model the ultra-short time-domain (TD) responses of deep sub-micron MOSFETs which leads to wideband models. This new method is suitable for modeling the devices used in high-speed or switching type circuits. The technique was developed based on applying an ultra-short impulse signal with 30 pico-second (ps) width to the devices. As a result, an easy-to-use wideband extension equivalent circuit model incorporating BSIM3v3 is derived in the modeling process. Experiments were conducted to reveal the feasibility of the technique. Results show that the generated wideband models (w-models) can be used to describe the TD responses of the MOSFETs with a time-scale down to ps order. That is, the proposed method is easy to establish good wideband (tens or even hundreds of GHz) deep sub-micron MOSFET models for describing their wideband characteristics. (C) 2004 Elsevier Ltd. All rights reserved.