Integrator vs Differentiator

Thread Starter

tjones91

Joined May 6, 2020
19
Hello, I am trying to learn more about integrators and Differentiators. I will post both schematics below.
I am seeing things online saying a differentiator has a changing input and provides a steady output and an Integrator circuit does the opposite, but then i see other articles that say otherwise.
Can someone explain in an easy to understand way what is a Differentiator circuit and what is an Integrator circuit, how they are different and what they are used for?
Thanks, P.s ( I do understand some of the basics of electronics and high and Low pass filters)
Differentiator Differrentiator.gif

Integrator
Intergrator.gif
 

Papabravo

Joined Feb 24, 2006
15,084
Without having taken a course in calculus, you have one hand tied behind your back when it comes to understanding. Let me try to simplify it for you.

  1. A differentiator measures the slope of the input waveform. The square wave does not have perfectly vertical edges, they have a slope to them, the capacitor quickly measures that slope and the output pops up to some value. Then the input levels off to a constant value, which means the slope is zero. Unfortunately capacitors can't discharge through a resistor as quickly as they charge without one, so the output decays exponentially back to zero, Now comes the falling edge of the input and the voltage on the capacitor goes negative to indicate the negative slope of the falling edge, and the imperfect exponential rise back to zero.
  2. An integrator measures the area underneath the waveform. The shaded area underneath the words "Input Signal". The voltage on the capacitor increases linearly as long as the squarewave pulse is above ground. Once we get the falling edge, the charge on the capacitor, that represents the area underneath the input waveform, drains away through the resistor back to the signal source.
 

crutschow

Joined Mar 14, 2008
26,405
Those are not true integrators and differentiators, but provide an RC exponential approximation of them.
A much closer to the theoretical ideal operation can be done with an op amp integrator or differentiator circuit.
 

Papabravo

Joined Feb 24, 2006
15,084
In fact, there are no real circuits you will ever see, besides all the ones you won't, that exhibit "ideal" behavior. Everything represents different orders of approximation.
 
Top