PHYS345 Electricity and Electronics

Answer for P14.9

stabilized differentiator

Ignoring the stabilizing resistor Ri for the time being, the feedback resistor Rf should be selected to be 25k to get the desired outcome with a 0.1 microFarad input capacitor.

From a MathCAD document (with edited graph):

Bode plot for unstabilized differentiator

To set a breakpoint at the intersection of the unstabilized differentiator gain and the op amp roll-off, an input resistor Ri is added so that 2 pi (8 kHz) (RC)i = 1; that is, Ri = 200 ohm.

Last updated Dec. 7, 1998.
Copyright George Watson, Univ. of Delaware, 1998.