Application of a charge-control model to high-voltage power transistors

Basic charge-control concepts are applied to the problem of predicting the static and large-signal switching characteristics of high-voltage transistors, with particular emphasis placed on the quasi-saturation region. Under the assumptions of unity base transport factor and one-dimensional current flow, simple equations for device electrical characteristics are derived in terms of readily determined device parameters. A two-region model is developed for predicting the turn-on process. Measured turn-on waveforms and collector characteristics are compared with the calculated behavior for a BVCE0= 400 V switching transistor. A comparison with hFE(Ic) data is also given for different temperatures. In all cases, good agreement with the predictions of the model is obtained. Implications of the model with respect to device design and characterization are discussed.