Q . Why CE Configuration is widely used in amplifier circuit?
The main utility of a transistor lies in its ability to amplify weak signals. The transistor alone cannot perform this function. We have to connect some passive components & a biasing battery. Such a circuit is then called an amplifier. In most of the applications we use a no: of amplifier stages. Such a connection of amplifier stages is known as cascaded amplifier. In such an amplifier,input resistance of the first stage acts as the load resistance to the source. The performance of the first stage is not disturbed when second stage is connected. For this output resistance of the first stage should be low & input resistance of second stage should be high. A good amplifier stage is one which has high input resistance & low output resistance. A transistor in CB configuration has a very low input resistance & very high output resistance. It is the reverse of what we desire. That is why CB configuration is unpopular . Input resistance of CC configuration is very high & output resistance is quite low. But the voltage gain of the CC amplifier is very low. Comparatively, the CE configuration is much better as regards its input& output resistances. Its input resistance is about 1 k? & output resistance is about 10 k? A transistor in the CE configuration makes a much better amplifier. The current gain,voltage gain 7 power gain of CE is much better than those of CB.