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Discuss the OP-Amp Differentiator

Discuss the OP-Amp Differentiator

Answers

Wilfred
- A differentiator is a circuit that performs differentiation of the input signal. In other words, a differentiator produces an output voltage that is proportional to the rate of change of the input voltage. Its important application is to produce a rectangular output from a ramp input. Fig. 9.17 shows the circuit of OP-amp differentiator. It consists of an OP-amp, an input capacitor C and feedback resistor R. Note how the placement of the capacitor and resistor differs from the integrator. The capacitor is now the input element.
inte71682019248.png

Circuit analysis: Since point A in Fig. 9.17 is at virtual ground, the virtual-ground equivalent circuit of the operational differentiator will be as shown in Fig. 9.18. Because of virtual ground and infinite impedance of OP-amp, all the input current ic flows through the feedback resistor R i.e. ic = iR.
inte7a1682019248.png
- Eq. (i) shows that output is the differentiation of the input with an inversion and scale multiplier of RC. If we examine eq. (i), we see that if the input voltage is constant, dvi/dt is zero and the output voltage is zero. The faster the input voltage changes, the larger the magnitude of the output voltage.
Wilfykil answered the question on August 16, 2019 at 12:21

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