Transistor Common Emitter Phase Shift in tamil

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Transistor Common Emitter Amplifier.
The common emitter transistor amplifier circuit is one of the mainstay circuits for use within electronic circuit design offering many advantages.
The common emitter circuit configuration is used in many areas of electronic circuit design: as an audio amplifier, as a basic switch for logic circuits, as a general analogue amplifier and in many other applications.
The common emitter circuit configuration provides voltage gain combined with a moderate current gain, as well as a medium input and a medium output impedance. As such the common emitter configuration is a good all round circuit for use in many applications.
It is also worth noting at this stage that the common emitter transistor amplifier inverts the signal at the input. Therefore if a waveform that is rising enters the input of the common emitter amplifier, it will cause the output voltage to fall. In other words it has a 180° phase change across the circuit.
Dependent upon the actual electronic circuit design itself, the common emitter does not use too many electronic components, sometimes as few as two resistors, although if the bias needs setting for analogue circuits, then four resistors and three capacitors may be used.
Common emitter transistor amplifier basics
Of the three types of transistor configuration used in electronic circuit design, the common emitter is the most widely used because of its key attributes.
The common emitter amplifier has the signal applied to the base and the output is then taken from the collector circuit. However, as the name of this circuit implies, the key attribute is that the emitter circuit is common to both input and output.
The common emitter configuration is equally applicable to both NPN transistor and PNP transistor variants. That said the NPN variety is more commonly used because of the more widespread us of NPN transistors.
Common emitter transistor amplifier characteristics summary
When selecting the transistor configuration to be used within an electronic circuit design, it is necessary to consider the various attributes of the three types: common emitter, common collector and common base, and select the one that is most appropriate.
The table below gives a summary of the major characteristics of the common emitter transistor configuration.
Common emitter amplifier impedance levels
One of the key attributes to be considered when undertaking any electronic circuit design are the impedance levels.
The input impedance is typically around 1kΩ, although this can vary considerably according to the circuit values and conditions. The low input impedance results from the fact that the input is applied across the base and emitter where there is a forward-biased junction,
Also the output impedance can be relatively high. Again this varies considerably upon the electronic component values chosen and current levels permitted. The output impedance may be as high as 10kΩ or possibly more. However if current drain allows higher current levels to be drawn, the output impedance can be reduced considerably. The level of resistance or impedance comes from the fact that the output is taken from the collector where there is a reverse-biased junction.
Common emitter transistor amplifier gain
Another important factor to be considered at the outset of the electronic circuit design is the gain level that can be achieved. There are two forms of gain that can be determined: current gain and voltage gain.
The current gain for the common emitter amplifier circuit is denoted by the Greek symbol β. This is the ratio of collector current to base current. This may be thought of as the ratio of output current to input current. To gain an accurate figure of the gain for a signal, the current gain for small input changes in current is often used. Using this the current gain, β, and the changes in input and output current are relate
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