n-p-n power transistor & regions in V-I characteristics

Q.  What does an arrow indicate in the below drawn schematic of V-I characteristics of n-p-n power transistor?
- Published on 23 Sep 15
V-I


a. Primary breakdown
b. Second breakdown
c. Quasi saturation
d. Active region

ANSWER: Quasi saturation
 

    Discussion

  • Satyawati   -Posted on 05 Oct 15
    Current-voltage characteristics of a power transistor are mainly categorized into four different regions. They are cut-off, active, quasi saturation and hard saturation regions.

    Among all these regions, active,cut-off and hard saturation regions are same as those of logic level transistors but the quasi-saturation region is totally different. Quasi-saturation region is formed due to lightly doped drift layer in power transistors.

    It is generally present between hard saturation and active regions. It is functionally applicable when the power transistor is to be operated at high switching frequency.

    Primary breakdown occurs due to conventional avalanche breakdown of collection base junction. Primary & secondary breakdowns are avoided by the associated large power dissipation. Apart from these, the transistor operates in active region only when the emitter junction is forward biased and the collector junction is reverse biased.

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