Advertisements
Advertisements
प्रश्न
Explain the working of the PNP transistor?
Advertisements
उत्तर
Working of p-n-p transistor:
- The majority of charge carriers in the emitter of the p-n-p transistor are holes.
- A typical biasing of a transistor is shown in figure (a). In this, the emitter-base junction is forward biased while the collector-base junction is reverse biased.
Figure (a) - At the instant when the EB junction is forward biased, holes in the emitter region have not entered the base region as shown in figure (b).
Figure (b) - When the biasing voltage VBE is greater than the barrier potential (0.6 – 0.7 V for Si transistors), many holes enter the base region and form the emitter current IE as shown in figure (c).
Figure (c) - These holes can either flow through the base circuit and constitute the base current (IB), or they can also flow through the collector circuit and contribute towards the collector current (IC).
- The base is thin and lightly doped, the base current is only 5% of IE.
- Holes injected from the emitter into the base diffuse into the collector-base depletion region due to the thin base region. When the holes enter the collector-base depletion region, they are pushed into the collector region by the electric field at the collector-base depletion region. The collector current (IC) flows through the external circuit as shown in figure (d). The collector's current IC is about 95% of IE.
Figure (d)
From the figure, we can conclude that IE = IB + IC Since the base current IB is very small we can write IC ≈ IE.
APPEARS IN
संबंधित प्रश्न
Why is the base of a transistor made thin and is lightly doped?
Why are the emitter, the base, and the collector of a BJT doped differently?
Which method of biasing is used for operating a transistor as an amplifier?
In a common base configuration, the transistor has an emitter current of 10 mA and a collector current of 9.8 mA. The value of base current is ______
Draw the circuit symbol for NPN and PNP transistors. What is the difference in the Emitter, Base, and Collector regions of a transistor?
Draw the circuit diagram to study the characteristic of the transistor in common emitter mode. Draw the input and output characteristics.
Assuming VCEsat = 0.2 V and β = 50, find the minimum base current (IB) required to drive the transistor given in the figure to saturation.
A transistor has a voltage gain A. If the amount βA of its output is applied to the input of the transistor, then the transistor becomes oscillator, when ______.
The condition to convert an amplified signal into an oscillating signal is ______
A transistor having α = 0.8 is connected in common emitter configuration. When the base current changes by 6 mA, then the change in collector current is ______.
In switching circuit, transistor is in ON state. Values of IC and IB are 5.2 mA and 10 µA respectively and value of RC is 1 k`Omega`. If Vcc is at 5.5 V, then VCE is ______.
ln switching circuit, transistor is in ON state and values of IC and IB are 4.2 mA and 5 µA respectively and RC= l k`Omega` and RB= 300 k`Omega`. If VBE = 0.5 V, find the value of VBB.
In case of npn transistors, the collector current is always less than the emitter current because ______.
For a common emitter configuration, if 'α' and 'β' have their usual meanings, the correct relationship between 'α' and 'β' is ______.
In a transistor, the thickness of the base region ____________.
In common emitter mode of transistor, the d.c. current gain is 20, the emitter current is 7 mA. The collector current is ______.
For an ideal diode, the current in the following arrangement is ______.
In common emitter amplifier, a change of 0.2 mA in the base current causes a change of 5 mA in the collector current. If input resistance is 2K `Omega` and voltage gain is 75, the load resistance used in the circuit is ______.
In a study of transistor as an amplifier, the ratio of collector current to emitter current is 0.98. The collector current is 3mA, then base current will be approximately ______.
A transistor having α = 0.8 is connected in a common emitter configuration. When the base current changes by 6 mA, the change in collector current is ______
A conducting wire has length 'L1' and diameter 'd1'. After stretching the same wire length becomes 'L2' and diameter 'd2' The ratio of resistances before and after stretching is ______.
In a p-n-p transistor circuit, the collector current is 10 mA. If 90% of the holes emitted from the emitter reach the collector, ______.
The transfer ratio of a transistor is 50. The input resistance of the transistor when used in the CE configuration is 1K Ω. The peak value for an AC input voltage of 0.01 V of collector current is ______.
Explain the working of the n-p-n transistor in a common base configuration.
How is a transistor biased for operating it as amplifier?
