It still has a current gain significantly high though the voltage gain is close to unity.
A: Because the output is the emitter which will follow the base.
The question does not quite make sense. It sounds like you are asking why does changing the emitter resistor in a class C common collector amplifier not affect the output voltage? If so, the answer is that the common collector is an emitter follower, meaning that the emitter will follow the base, less the base-emitter junction voltage, within the limits of hFe. The resistor is simply there to ensure output biasing when the base voltage goes low.
what is common collector
emitter follwer
current gain
The output of a common emitter stage is inverted, it is not out of phase.
Common collector amplifier can be used as a voltage buffer and in impedance matching
No voltage gain
the common collector can use as voltage buffer
Current gain. At the cost of no voltage gain.
The question does not quite make sense. It sounds like you are asking why does changing the emitter resistor in a class C common collector amplifier not affect the output voltage? If so, the answer is that the common collector is an emitter follower, meaning that the emitter will follow the base, less the base-emitter junction voltage, within the limits of hFe. The resistor is simply there to ensure output biasing when the base voltage goes low.
Common-emitter gives more voltage gain because a common-collector amplifier has a voltage gain of 1. But a common-collector can have a power gain because the input impedance is much more than the output impedance.
what is common collector
We bias the common emitter amplifier to have a collector-emitter voltage of one half of Vcc in order to set the operating point halfway between the two extremes.
In the common emitter configuration, a class A amplifier, an increase in base voltage (the input) leads to an increase in base-emitter current which leads to a proportionately larger increase in base collector current. That pulls the collector towards the emitter, which decreases the collector voltage. Since the collector is the output, this configuration is an inverting amplifier.
In the common emitter amplifier, an increase of base-emitter current causes a larger increase of collector emitter current. This means that, as the base voltage increases, the collector voltage decreases. This is a 180 degree phase shift.
as voltage amplifiercurrent followeri am yoges
An amplifier amplifies voltage or current. The most basic amplifier consists of a transistor where a signal is fed into the base and is output to the emitter or collector. For simple, low frequency applications (not RF), it may be simpler to use an operational amplifier (op amp) than designing your own amplifier. Also, the data sheets provide very helpful schematics for creating an amplifier. A very common one is the 741; these are also fairly cheap.