# Explain the working of CE configuration of a BJT and draw its input, output characteristics.

Explain the working of CE configuration of a BJT and draw its input, output characteristics.

Output characteristics:-

Cut off, Active and saturation regions of a transistor:

1.Transistor Biasing:- The application of suitable dc voltages across the transistor terminals is called biasing. Each junction of a transistor may be forward biased or reverse biased independently. These are following three different ways of biasing a transistor, which is also known as modes of transistor operation.

2.Forward active:- Emitter-Base junction is forward biased Collector- base junction is reverse biased.

3.Saturation Region:- Emitter-Base junction is forward biased Collector- base junction is forward biased In this mode transistor has a very large value of current. The transistor is operated in this mode, when it is used as a closed switch. Here, there is a large change in the collector current IC with a small change in VCE.

4.Cut- off Region:- Emitter-Base junction is reverse biased Collector- base junction is reverse biased In this region both the junctions are Reverse Biased. In this mode transistor has zero current. The transistor is operated in this mode, when it is used as an open switch. Since the collector base junction is reversed biased, the current due to majority carriers flows from collector to emitter which is represented by ICEO Output characteristics of Common Emitter Transistor

Output resistance: ro=ΔVceΔIc

IB = constant

Current gain = βdc=IcIb

VCE =constant

βac=Ic/Ib

VCE =constant

Modes of transistor action: Input characteristics:- It is the graph of input current Ib v/s input voltage Vbe at a constant output voltage Vce. It resembles the characteristics of a forward-biased diode. The input current Ib increases as the input voltage Vbe increases for a fixed value of Vce. As the Reverse-Bias voltage Vce increases, Depletion region in the collector –base junction increases. Hence the width of the base available for conduction decreases. Hence, Ib decreases due to early effect and the graph shifts towards X-axis.

Dynamic input resistance =

Ri=ΔVbe/ΔIb

where VCE = constant Output Characteristics

 The family of output characteristics curves of a bipolar transistor is given below. The curves show the relationship between the collector current (IC) and the collector-emitter voltage (VCE) with the varying of base current (IB).  We know that the transistor is ‘ON’ only when at least a small amount of current and small amount of voltage is applied at its base terminal relative to emitter otherwise the transistor is in ‘OFF’ state. ## Related questions

Explain the working of CB configuration of a BJT and draw its input, output characteristics.
Last Answer : Common Base Configuration   In common base configuration, emitter is the input terminal, collector is the output terminal and base terminal is connected as a common terminal for both input and output. ... For each voltage level of the output voltage (VCB), the output current (IC) is recorded ... Describe the working of a PN junction diode with neat diagrams. Also explain its V-I characteristics.
Last Answer : Working of a PN junction diode:   if an external potential is applied to the terminals of PN junction, it will alter the potential between the P and N-regions. This ... circuit. When the reverse bias input voltage has reached the breakdown voltage, reverse current increases spectacularly.  ... Draw the circuit diagram for half-wave rectifier and explain its working.
Last Answer : Rectifier is an electronic device which converts the alternating current to unidirectional current, in other words rectifier converts the AC voltage to DC voltage. We use rectifier in almost all the ... but this current is almost negligible. And voltage across the load resistance is also zero. ... Explain the working of Zener diode and mention its applications.
Last Answer : Symbol of Zener Diode    We can identify the terminals of zener diode by observing a black color ring at cathode terminal (refer the first figure in this post). If it ... for voltage regulation, as reference elements, surge suppressors, and in switching applications and clipper circuits.  ...  