A pole at DC is called a true integrator. A zero may also be called a differentiator. However, since you can't buy a zero without buying a pole, there are no true differentiators. Those of you who have taken calculus can appreciate this. 2 Complex poles.
Impedance increases away from resonance.
2 Complex Poles. Impedance decreases away from resonance. We will defer discussion of complex poles and zeros to a future article. Consider an R-C coupling mechanism from plate of one stage to grid of the next stage. For inductively coupled circuits, you must also consider the winding resistance of the inductor.