Why there is a 180 degree phase shift in output signal of CE amplifier?

 

When the base current of a common-emitter transistor increases then the base voltage increases a little. The collector current also increases. The current in the collector resistor increases which increases the voltage drop across it so the collector voltage decreases which is 180 degrees to the small change in base voltage.

 

When the base current of a common-emitter transistor increases then the base voltage increases a little. The collector current also increases. The current in the collector resistor increases which increases the voltage drop across it so the collector voltage decreases which is 180 degrees to the small change in base voltage.

Thanks for the response.
Can you please elaborate on how the increase in collector resistor voltage drop decreases the collector voltage ? I am a bit confused.....

 

Thanks for the response.
Can you please elaborate on how the increase in collector resistor voltage drop decreases the collector voltage ? I am a bit confused.....

Hi Ramesh:

If you think of the load resistor and the collector circuit as being a VOLTAGE DIVIDER, it's easy to visualize. The sum of the voltage drop across the load resistor and the voltage between collector and ground always have to equal the supply voltage. The load resistor is fixed while the effective resistance of the emitter-to-collector path varies with the input signal.

Hope this helps.

eric

 

Hi Ramesh:

If you think of the load resistor and the collector circuit as being a VOLTAGE DIVIDER, it's easy to visualize. The sum of the voltage drop across the load resistor and the voltage between collector and ground always have to equal the supply voltage. The load resistor is fixed while the effective resistance of the emitter-to-collector path varies with the input signal.

Hope this helps.

eric

thanks .....
I got that