Simulation and assessment of non-quasi-static current crowding in scaled bipolar circuits

A novel method of accounting for non-quasi-static (NQS) effects in a seminumerical bipolar junction transistor (BJT) circuit model, based on the use of the previous time-step solution in the current time-step analysis, is used to simulate and assess transient current crowding is scaled bipolar circuits. The model, supported by numerical device simulations, reveals significant NQS delay, even in circuits comprising submicron BJTs. It is noted that the novel modeling/implementation involving the use of the previous time-step solution to update the model for the current time-step analysis could be a viable means of accounting for general NQS behavior in semi-numerical transient device/circuit simulation. For example, the transient-field (dE/dt) dependence of hot-electron drift velocity in scaled BJTs, which portends a NQS aspect of the velocity overshoot, can be accounted for via the methodology described