For example if the we give 10V signal with 1k ohm source impedance to the 1M input ohm which is connected to the input of the transistor or other electronic peripheral then the input impedance will be In the transistor amplifier the input impedance should be high because it will stop the loading of the circuit. Input impedance: The voltage source which is connected to the impedance, which is connected to the input, is called input impedance. The specifications are input impedance, efficiency, bandwidth, gain, slew rate, linearity, stability, etc. We need to consider the following specifications before choosing the transistor amplifier. Note: Most of amplification circuits uses CE configuration because it has high gain and high input impedance. Common Emitter configuration (CE): in this configuration emitter is connected to ground and we will have input impedance will be high, output impedance will be medium and gain will be high.Common Collector configuration (CC): in this configuration collector is connected to ground, we have low output impedance for high input impedance and gain for this configuration is very good when compared to CB configuration.Gain for this configuration will be very low. Common Base configuration (CB): in the CB configuration we will connect base of the transistor to ground, which has very low input impedance which will give very low output impedance with very low amplification.Transistor can be used as amplifier in the following three configurations. We will discuss more about this topic in later session. If transistor wants to works as an amplifier we should make the transistor to work in active region which lies between the saturation and cutoff region. Transistor will get completely on at saturation region and completely get off at cutoff region. Here we will concentrate how transistor is used as amplifier. Applications of amplifier are of wide range, they are mainly used in communications, controllers, audio and video instruments etc. The input signal may be a current signal, voltage signal or a power signal amplifier will amplify the signal without changing its characteristics. Amplification is a process of increasing the signal strength by increasing the amplitude of a given signal with out changing its characteristics.

Transistor amplifire