Let's see how were the calculations, hereOriginally posted by oracle_dfx@Feb 23 2005, 08:14 PM
Hi, Would anyone know why the output signal of the common emitter amplifier is out of phase by 180º? If available, pls include the computations that mathematically prove the inversing of the signal.. Thanks!
thanx a lot for the answer, this precisely was my question.It's all very well to go through the rigorous analysis, but it's also important to have a good conceptual understanding of this phase inversion. The CE transistor gets its collector bias from Vcc through a load resistor. The collector side of the resistor is the output. When the transistor is turned on harder (through an increase in base potential) more current flows into the collector through the load resistor, increasing the voltage drop across the resistor. Since the top of the resistor is at a fixed voltage (Vcc), the collector side has nowhere to go but down. Hence a rise in base potential causes a fall in collector potential (all with respect to ground, of course).
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