How collector base junction is reverse biased in common emitter configuration?
Table of Contents
- 1 How collector base junction is reverse biased in common emitter configuration?
- 2 Why is base-collector reverse biased?
- 3 Which region emitter and collector junctions are reverse biased?
- 4 When the collector junction is reverse bias and emitter junction is forward biased the operating region of the transistor is called?
- 5 Can I reverse the bias of the be junction of BJT?
- 6 Is the base-emitter junction Je forward or reverse biased?
How collector base junction is reverse biased in common emitter configuration?
The collector ( N} ie than more positive than Base – Hence B- b C junction is Reverse Biased. This is natural in a PNP or NPN transistor because the two pn junctions are in opposite polarity so a natural gradient in the three voltages from high to low biases the two junctions oppositely.
Why is base-collector reverse biased?
Collector is always reverse-biased w.r.t base so as to remove the charge carriers from the base-collector junction.
What is common collector configuration of BJT?
The Common Collector Amplifier is another type of bipolar junction transistor, (BJT) configuration where the input signal is applied to the base terminal and the output signal taken from the emitter terminal. Thus the collector terminal is common to both the input and output circuits.
When the emitter base junction of transistor is reversed biased collector current?
High-frequency BJT performance
| gm | 80 mS(@IC = 2 mA) |
|---|---|
| rπ | 1.1 kΩ |
| rμ | 270 kΩ |
| Cπ | 130 fF |
| Cμ | 8 fF |
Which region emitter and collector junctions are reverse biased?
Transistor biasing
| EMITTER JUNCTION | COLLECTOR JUNCTION | REGION OF OPERATION |
|---|---|---|
| Forward biased | Forward biased | Saturation region |
| Forward biased | Reverse biased | Active region |
| Reverse biased | Forward biased | Inverse active region |
| Reverse biased | Reverse biased | Cutoff region |
When the collector junction is reverse bias and emitter junction is forward biased the operating region of the transistor is called?
Active Region: The transistor is said to operate in an active region when the emitter junction is biased in forward direction and the collector junction in the reverse direction.
In which region are both the collector-base and base-emitter junctions reverse biased for BJT?
cut-off region
In the cut-off region, the emitter-base junction and collector-base junction both junctions are reverse biased.
Why is the collector junction in a circuit normally reverse biased?
The collector junction is normally reverse biased so it can block the current when the base current is zero. When the base-emitter current is not zero then carriers are generated at the base collector junction which allows a much larger current to flow across the reverse biased base-collection junction and through the emitter.
Can I reverse the bias of the be junction of BJT?
Note, in general, that the limit is fairly low (5V..8V usually, even for power transistors), which is a strong hint that reversing the bias of the BE junction of a BJT is a risky business. So, unless you know exactly what you are doing, it is better to avoid reversing the bias of the BE junction for more than 1-2V.
Is the base-emitter junction Je forward or reverse biased?
As mentioned earlier, in every configuration, the base-emitter junction JE is always forward biased and collector-base junction JC is always reverse biased. Therefore, in common base configuration, the base-emitter junction JE is forward biased and collector-base junction JC is reverse biased.
What is the base potential of a collector-base junction?
The input in this case is the base current. In its usual (active) mode of operation, the collector-base junction is kept reverse-biased to suck out the minority carriers that are injected continuously into the base via the emitter. Thus, the base potential is higher than the emitter potential but lower than the collector potential.