Operational Amplifier Applications Unit 2 – Integration and Differentiation
You can also think of a passive integrator as a voltage divider with the output taken across the
capacitor.
Increasing the frequency of an integrator's input signal causes the output amplitude to decrease.
The top waveform in this group represents an input pulse to a passive integrator.
The remaining waveforms are the resulting output for different relationships of input pulse width
(PW) to the RC time constant.
For the first output, the RC time constant is larger than the pulse width. The input pulse ends
before the capacitor charges completely.
For the second output, the RC time constant approximately equals the pulse width. The slight
rounding at the top of the waveform is due to the exponential nature of the capacitor's charging
action.
For the third output, the RC time constant is much smaller than the pulse width. The capacitor
charges up relatively quickly and has finished charging long before the input pulse ends.
In practice, a common use of the integrator is to produce a linear ramp waveform from a square
wave.