Help with understanding Self-biasing Amplifier

Thread Starter


Joined Jan 26, 2010

I was doing some reading about this type of amplifier and I came across:

The analogue design tools can be used to determine how the circuit performs in real time. One method of doing this is to apply a defined stimulus to the circuit and examine how the output changes with time. As an example, you could apply a pulse input to the circuit and examine how quickly the output voltage responds.

Note that the output signal is inverted compared to the input.

I want to ask why is the output signal inverted?

Thank you


Joined Dec 20, 2007
You forgot to post the schematic so I am just guessing that a self-biased transistor has a single bias resistor from its collector to its base.

Thread Starter


Joined Jan 26, 2010
I did some research and found this

This is because this is an inverting amplifier and it produces an output 180 degrees out of phase with the input signal.

Is that the reason???


Joined Jul 17, 2007
The phase shift is actually not exactly 180° due to propagation delay, but it's close - so close that at audio frequencies, you would be hard-pressed to tell the difference.

If it was a non-inverting amplifier, phase shift would be close to zero degrees.