Suppose I have a circuit with two ports. One port is considered the input, and the second port is considered the output.
Assume it's described via
$$V_{out} = \frac{V_{in}}{2}$$
Now assume there's no voltage applied to the input terminals.
Supply the output port with 5 V. If I measure the terminals of the input port, will I see 10 V?
In general, the answer is no, of course, as a voltage divider will show.
What do you call circuits that do satisfy the behavior where you measure 10 V at the input port given a supplied 5 V source at the output port? I'm asking for a general term, but using an example to illustrate what I mean.
Best Answer
In the specific case where \$V_\text{out}\$ and \$V_\text{in}\$ take on only two possible levels, the device is known as a bidirectional (logic) level translator/converter/shifter.
In the specific case where \$V_\text{out} = V_\text{in}\$, it is of course a wire or transmission line.
In the specific case where the device can be switched between \$V_\text{out} = V_\text{in}\$ and no connection, it is a switch — or, if implemented in semiconductors rather than mechanically, specifically an analog switch or transmission gate.
I do not expect there is a formal term for the general case of this behavior because it's not a realistic "found" behavior in a circuit except in special cases that are best considered on their own. That said, “bidirectional” would be a reasonable word to use — just don't expect it to automatically imply everything you've described here.