Electronic – Confusion between Input/Ouput Impedance and Thévenin’s theorem

impedanceinput-impedancethevenin

I'm bit confused about what Input Impedance or Output Impedance is. I tried to read Wikipedia's page (https://en.wikipedia.org/wiki/Input_impedance) but I find it hard to follow.

Is the Input Impedance of a circuit (defined between two terminals A and B) the same as the equivalent impedance obtained by applying Thévenin's Theorem? What is the Output Impedance instead?

I'm interested in the general theory, an example (with the diagram of a circuit showing input and output Impedance) would be really appreciated

Best Answer

When you speak of a systems input or output impedance, you're implying that it fits with the Thevenin model of a voltage supply in series with an impedance, which may be reactive. Usually an input will be a zero voltage in series with an impedance, but not always.