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What is the condition to operate BJT in cut off region?
Whenever we observe the terminals of a BJT and see that the emitter-base junction is not at least 0.6-0.7 volts, the transistor is in the cutoff region. In cutoff, the transistor appears as an open circuit between the collector and emitter terminals. In the circuit above, this implies Vout is equal to 10 volts.
When a BJT is operating in the cut off and saturation regions it functions as?
When the transistor is either in saturation or cutoff modes, it dissipates little power. When in cutoff, there is no current flow between collector and emitter thus P = Vce ∗ Ic = 0. When in saturation, the current may be high, but Vce is very small, keeping the power dissipated by the transistor very low.
What does VBE = VBE ( on ) mean in a BJT?
For a BJT as you say if VBE < VBE (ON) the transistor is in cut-off, when you get to VBE = VBE (ON) the base and the emiter of the transistor behave like a diode, with the voltage drop of a diode (0.6-0.7V) it means you “can’t” have more than VBE = VBE (ON), you only can have the voltage drop across the diode.
When does the BJT operate in the cutoff region?
As shown again in figure 4, the BJT operates in the cutoff region when I B is equal to zero. In this case, there should be no current that will flow through the collector. However, in reality, there will be a very small collector leakage current that will flow due to the thermally produced carriers.
Can a BJT be used as a closed switch?
For example, the concept of cutoff and saturation regions can be used to operate a BJT as a switch. When the BJT is operating in the cutoff region, then it could be used like an open switch while if it is operating in the saturation region, the BJT could be used as a closed switch.
Which is the first parameter in BJT operation?
So the first parameter is the DC beta ( βDC) which is equivalent to the hybrid parameter ( hFE) that you can find on the datasheet of transistors. DC beta ( βDC) is the ratio of the DC collector current and the DC base current which means that it is the DC current gain of a transistor.