Power transistor - Drift region affected parameters

Q.  Which among the below stated parameters gets affected due to drift region in the power transistor?
- Published on 24 Sep 15

a. Breakdown voltage
b. On-state losses
c. Switching time
d. All of the above

ANSWER: All of the above


  • Satyawati   -Posted on 05 Oct 15
    By comparing the power transistor with the logic level transistor, it is obvious that the mechanism of operation for of them is exactly similar with the only difference that power transistor consists of an additional collector drift region.

    But, the collector drift region does not play a vital role only when the power transistor operates in an active region. This collector drift region has far-reaching effects on breakdown voltage, on state losses as well as switching time of power transistor.

    Due to low level of doping, the collector drift region results in increasing the voltage blocking capacity. Therefore, the width of this layer (n- region) plays a crucial role in deciding the level of breakdown voltage.

    In addition to this, the collector drift region also increases the on state device resistance,which ultimately increases the on state power loss.

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