OpAmp as a Differentiator - Operational Amplifiers Types Tutorials Series

Op-amp as a Differentiator

•The two op-amp configurations shown below perform the function of differentiation

–The circuit on the left is the complement of the integrator circuit shown on slide 2-14, simply switching the capacitor and resistor

–The circuit on the right differentiates by replacing the capacitor with an inductor
•For the circuit on the left we can write

–i1 = C(dvIN/dt) = i2 = (0 – vOUT)/R2  or 

  vOUT = - R2C (dvIN/dt)

•Similarly, for the circuit on the right we can obtain

vOUT = - (L/R1) (dvIN/dt)

•By nature a differentiator is more susceptible to noise in the input than an integrator, since the slope of the input signal will vary wildly with the introduction of noise spikes.