it can be seen that: when , the circuit acts as a differentiator; when , the circuit acts as a voltage follower or buffer; when , the circuit acts as an integrator. If (say), there occurs one zero at and two poles at . For such a differentiator circuit, the frequency response would be From the above plot, we observe that: when , the circuit acts as a differentiator; when , the circuit acts as an integrator. Applications The differentiator circuit is essentially a high-pass filter. It can generate a square wave from a triangle wave input and produce alternating-direction voltage spikes when a square wave is applied. In ideal cases, a differentiator reverses the effects of an integrator on a waveform, and conversely. Hence, they are most commonly used in wave-shaping circuits to detect high-frequency components in an input signal. Differentiators are an important part of electronic analogue computers and analogue PID controllers. They are also used in frequency modulators as rate-of-change detectors. A passive differentiator circuit is one of the basic electronic circuits, being widely used in circuit analysis based on the equivalent circuit method. See also Integrator Inverting differentiator at op amp applications References Analog circuits