What makes an emitter follower a common collector?

What makes an emitter follower a common collector?

The emitter follower or common collector circuit configuration provides a high input impedance and a low output impedance. This means that the emitter follower circuit provides an ideal buffer stage,…

How does an emitter follower transistor amplifier work?

The emitter follower transistor amplifier has a very straightforward circuit. The base is connected to the previous stage, and often this may be directly connected as this can save on additional bias resistors which lower the input impedance and hence increase the loading to the previous stage.

When is an emitter-follower used in a BJT circuit?

In a BJT configuration when the emitter terminal is used as the output, the network is called an emitter-follower. In this configuration the output voltage is always a shade lower than the input base signal due to the inherent base to emitter drop. In simple terms, in this type of transistor circuit the emitter seems to be following

Why is the output VO called an emitter follower?

As understood earlier, the output Vo appears to be “following” the input signals levels Vi, through an in-phase relationship, and this represents its name emitter follower. The emitter-follower configuration is mainly used for impedance-matching applications, due to its high impedance characteristics at the input and a low impedance at the output.

What kind of transistor has an emitter follower?

An emitter follower is one of the standard transistor configurations which is also referred to as common collector transistor configuration. Let’s try to first understand what’s an emitter follower transisto r and why it’s called a common collector transistor circuit.

How did the emitter follower amplifier get its name?

This name is derived from the fact that the emitter voltage “follows” that of the base circuit – the circuit has unit voltage gain. The emitter follower transistor amplifier has a very straightforward circuit.

How is the resistance of an emitter follower calculated?

As it is normally used as a buffer amplifier, this is the key parameter. The input resistance can easily be calculated for a circuit because it is β times the resistor R1, where β is the forward current gain of the transistor. The simplest way of connecting an emitter follower is to directly couple the input as shown below.

How did the common collector circuit get its name?

The common collector transistor circuit configuration gains its name from the fact that the collector circuit is common to both input and output circuits, the base being associated with only the input, then the emitter with the output only. The other name for the common collector is emitter follower.