Advertisements
Advertisements
प्रश्न
Explain the working of the n-p-n transistor in a common base configuration.
Advertisements
उत्तर
The common base configuration for n-p-n transistor
In a Common Emitter configuration, the emitter of the transistor is common to both the input and the output.
Working:
Biasing of n-p-n transistor
- The majority of charge carriers in the emitter of the n-p-n transistor are electrons.
- In the above figure, the emitter-base junction is forward-biased while the collector-base junction is reverse-biased.
- At the instant when the EB junction is forward biased, electrons in the emitter region have not entered the base region as shown in the below figure.
Injection of majority carriers into base - These electrons 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.
- Electrons injected from the emitter into the base diffuse into the collector-base depletion region due to the thin base region. When the electrons enter the collector-base depletion regions, they are pushed into the collector region by the electric field at the collector-base depletion region. collector current (IC) flows through the external circuit as shown in the below figure. The collector's current IC is about 95% of IE.
Electron flow through a transistor - From the above 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?
In a common-base connection, the emitter current is 6.28 mA and the collector current is 6.20 mA. Determine the common-base DC current gain.
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 ______
In a transistor amplifier, IC = 5.5 mA , IE = 5.6 mA. The current amplification factor β is ______
Draw the circuit symbol of the PNP transistor.
With the help of a neat circuit diagram, explain the transistor as an amplifier?
The light emitted in an LED is due to
Give the Barkhausen conditions for sustained oscillations.
Explain the need for a feedback circuit in a transistor oscillator.
What is rectification?
Transistor functions as a switch. Explain.
Least doped region in a transistor ____________.
In the study of transistor as an amplifier, the ratio of collector current to emitter current is 0.98 then the ratio of collector current to base current will be ______.
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 an npn transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector, the emitter current (IE) and base current (IB) are given by ____________.
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 ______.
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 transistor is used as a common emitter amplifier with a load resistance 2 KΩ. The input resistance is 150 Ω. Base current is changed by 20 µA which results in a change in collector current by 1.5 mA. The voltage gain of the amplifier is ______.
The reverse bias in a junction diode is changed from 8V to 13V, then the value of the current changes from 40μA to 60μA. The resistance of junction diode will be ______.
A common emitter amplifier circuit built using an n-p-n transistor is shown in the figure. Its DC current gain is 300, RC = 4 kΩ and VCC = 20 V. What is the minimum base current for VCE to reach saturation?
The current amplification factor for a transistor in its common emitter mode is 50. The current amplification factor in the common base mode of the transistor is ______.
The collector current in a common-emitter transistor amplifier is 4 mA. When the base current is increased by 20 µA, the collector current increases to 6 mA. The current gain is ______.
How is a transistor biased for operating it as amplifier?
In a CE amplifier, the current gain is 80 and the emitter current is 9 mA. The base current is ______.
Define peak value of alternating signal.
Define β
