## PHYS345 Electricity and Electronics

**Answer for P14.9**

Ignoring the stabilizing resistor R_{i} for the time being,
the feedback resistor R_{f} 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):

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

"http://www.physics.udel.edu/~watson/phys345/protected/exercises/answers/P14-9.html"

Last updated Dec. 7, 1998.

Copyright George Watson, Univ. of Delaware, 1998.