In studies [1,2], by mathematical simulation of the electric conduction of multibarrier heterostructures with a variable doping level, within the context of the quasi hydrodynamic (thermal) model of electron drift [3], the bistability of the voltage-current characteris tics (VCCs) of the heterostructures under discussion was for the first time specifically demonstrated in a sufficiently wide range of variation in temperature and in structure parameters (doping levels and composi tion). This result, which, on making minor improve ments in the simulation algorithm, we could represent in the form of pronounced S shaped VCCs with the corresponding electric instability (Fig. 1), testified that further investigation, including experimental one, is topical. It should be noted that the assumption that such instability is possible was for the first time made by R.A. Suris and V.A. Fedirko in study [4]. It is clear that, in the context of preparation to the interpretation of the results of the forthcoming experiments, of spe cial importance is the generalization of the stationary theoretical model used in [1,2] to the time domain, i.e., construction of a nonstationary theoretical model that describes the response of the system under inves tigation to a varying electric action.To this end, at first sight, it would be sufficient to simply introduce the corresponding time derivatives into the system of fundamental equations for the high field electron drift used in [1,2]. However, the extremely high laboriousness of this direct approach to the construction of algorithms and their software implementation impelled us to search for a simpler and practical method for estimating the corresponding transient processes. With this method, a stationary version of the approximate analytical model of the instability under consideration is preconstructed. In this case, a number of known analytical approaches well proven by semiconductor structure physics will be used. Next, on confirming the adequacy of the con structed analytical description by the closeness of the resulting stationary S shaped VCCs to the results obtained with the numerical model, we will transform Abstract-By mathematical simulation of the electric conduction in multibarrier heterostructures, static voltage-current characteristics (VCCs) whose S shape is indicative of the corresponding electric instability have been obtained. In order to analyze the dynamic parameters of this instability, an analytical model of the instability under investigation has been constructed with the use of the known approximations of semicon ductor physics. The static version of the analytical model also provides an S shaped VCC that is close to the corresponding results of the numerical simulation. With this closeness considered as a confirmation of the validity of the developed analytical model, the small signal version of this model is generalized to the case of a harmonic electrical disturbance. A clear physical interpretation of the instability under consideration in terms of a positive ...