common collector configuration is called as emitter follower.therefore collector should be grounded, why emitter is grounded?how the voltage gain is unity? **broken link removed**
common collector configuration is called as emitter follower.therefore collector should be grounded, why emitter is grounded?how the voltage gain is unity? **broken link removed**
hi sandy,
The collector is not grounded, its connected to the +Vrail, so its a 'common' collector, which is connected to 0V via the Vrail decoupling caps.
Regards the unity gain, consider how much negative feedback the emitter signal generates with respect to the base signal.
In an emitter follower, the collector is indeed connected to the +ve rail (assuming an NPN transistor), but, from a signal point of view the collector is at ground potential.
Not shown in the circuit in the OPs link, Vcc should be decoupled to the "ground" line with a capacitor which has a low reactance at the lowest frequency of interest.
Thus, Vcc is at signal ground potential, hence the collector is grounded at signal frequencies.