It is shown that the stationary distribution of ballistic current carriers moving across a thin doped base is unstable if there exists a negative effective mass (NEM) part in the carrier dispersion law. Under such a condition, a regime with a quasistationary current oscillations is established for a wide range of voltages across ballistic diode. The oscillation frequency and amplitude depend on the base length, doping concentration, and applied voltage. The current oscillations take place in a short-circuit regime (in absence of an external resonator). We consider asymmetric double quantum wells and/or composite ΓX quantum wells as possible structures allowing for the required dispersion relation with NEM part. Carrier dynamics in these structures are described quasiclassically and the validity of such a treatment is discussed.

No abstract

We present a new approach to model delay of the digital cell in VDSM IC designs. It provides higher accuracy for both delay and transition time than the conventional effective capacitance approximation. The cell is modeled by an effective current source that emulate the behavior of the transistor network. The proposed model is based upon the standard timing tables of the characterized cell.

No abstract

No abstract