Why we obtain inverting signal (180 out of phase ) in CE configuration
The inversion can be easily seen intuitively without any complex circuit analysis. If you pull up on the base of the NPN device (increase the voltage), the collector current will increase. As the collector current increases, the voltage across the load resistor will increase and this results in the output voltage dropping. The output voltage decreases in response to an increasing input voltage… thus the inversion… and this can be represented as a 180 degree phase shift.
strongCommon emitter/strong input strongoutput/strong phase relationship. The strongcommon emitter transistor amplifier/strong is the only strongconfiguration/strong that gives an inversion, 180°, between the input and strongoutput/strong signals. The reason for this can be seen from the fact that as the input voltage rises, so the current increases through the base circuit
The negative alternation of an AC strongsignal/strong will cause a decrease in IB this action then causes a corresponding decrease in IE through RL(load). The output strongsignal/strong of astrongcommon- emitter/strong amplifier is therefore strong180/strong degrees strongout of phase/strong with the inputstrongsignal/strong.
As in ce configuration strongbase current is directly proportional to base voltage/strong and it also increases the collector current which create a strongvoltage drop in the resistor across the collector /strongas the output is situated below the collector resistance the output voltage thus decreases as the voltage drop across the collector resistor increases .thus produces a phase shift of 180 degreesbr /and we can verify this by kirchoff's law,strongVcc=Icc+Vout/strong .here when collector current increases output voltage must decrease.