Ceramic resonators are cheap,narrowband filters used in inexpensive FM radio (etc). If you put one in the feedback path of an op-amp you'll meet the criteria d

Ceramic resonators are cheap,narrowband filters used in inexpensive FM radio (etc). If you put one in the feedback path of an op-amp you'll meet the criteria described by the physics definition but putting that same component on the input of the op-amp may result in an undetectable signal.