A generalized analytical model for the quantum well injection transit time diode

A generalized small-signal model of the quantum well injection transit time (QWITT) diode derived from the authors' previous large-signal model (see. ibid., vol.35, p.2315-2322, Dec. 1987), which includes not only the carrier space-charge effects but also the velocity transient effects and the carrier diffusion effects is presented. Simple closed forms for the device impedance have been obtained for efficient computation, where only one-dimensional integrations are required. It can be applied to any fashion of time dependence of the velocity transient and diffusivity transient, adopting a Gaussian form for the spatial profile of injected carriers. Using the formulas, the small-signal behavior and the design criteria for the QWITT diode are analyzed. Large-signal impedance of the device can also be estimated by the formulas.<
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