Question

What is an amplifier? Draw the simple circuit of the transistor in CE mode.

Answer 1

Hint: The amplifier is a circuit that can amplify the given input signals and hence make the signal suitable for transmission and processing. The transistor amplifiers can be classified as common emitter, common base, and common collector The common emitter amplifier is the one with the emitter connected to ground.

Complete step-by-step answer:
An amplifier is a generic term used to describe a circuit that produces an increased version of its input signal or we can say that the circuit or device which can amplify the given input signal.
What is the need for the amplifier? We have many signals from nature which we sense using the sensors. But these signals are very low in strength when we cannot directly use them for analysis and transmission. So we need to amplify the signal transmission and processing. For this process, we need the amplifiers to amplify or to increase the strength of the signals.

However, not all amplifier circuits are the same as they are classified according to their circuit configurations and modes of operation.
In “Electronics”, small-signal amplifiers are commonly used devices as they can amplify a relatively small input signal, for example from a Sensor such as a photo-device, into a much larger output signal to drive a relay, lamp or loudspeaker for example.
There are many forms of electronic circuits classed as amplifiers, from Operational Amplifiers and Small Signal Amplifiers up to Large Signal and Power Amplifiers. The classification of an amplifier depends upon the size of the signal, large or small, its physical configuration, and how it processes the input signal, which is the relationship between the input signal and the current flowing in the load.
The Transistor amplifiers can be classified as Common emitter and common base end common collector.

The common emitter amplifier can be drawn as :

Note: The common emitter amplifier is the transistor amplifier with the emitter of the transistor connected to the ground. Similarly, when the base of the transistor is connected to the ground, we call it a common base amplifier and if the collector the transistor is connected to the ground the configuration is called the common collector amplifier .