Effects of current localization in high-power microgate bipolar switches with nonideal interconnection between controlled cells

The influence of nonideal interconnection between controlled cells in bipolar microgate switches on current localization at the turn-off stage is analyzed. To estimate the resistance of the distributed electrodes, the entire device is represented as two parallel subsystems of controlled cells interconnected via the effective resistance of the gate circuit. Different scenarios of the turn-off process at nonideal couplings between the cells are numerically simulated for three turn-off circuit regimes by the example of an integrated thyristor with external field control. The turn-off scenarios are studied versus the effective resistance of the gate-off circuit and the ratio between the working surface areas of the cellular subsystems. Limitations on the ultimate switched current are compared. For small-scale inhomogeneities in the series resistance of the gate circuit, the maximum turn-off current in the cascode mode and using a negative voltage source remains an order of magnitude higher than that under the emitter short-circuit conditions.