I’m trying to create a differentiator op-amp. The input signal is a triangular wave of frequency 100Hz and amplitude 1V. The circuit I have designed features a series resistor (Rin) and capacitor. Through trial and error, I calculated Rin to be 100 but I do not understand why it has to be 100. Please can someone help?

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  • \$\begingroup\$ What is the impedance of the capacitor at that frequency? find that and you will have your answer. \$\endgroup\$ – Reroute Jun 6 at 11:57
  • \$\begingroup\$ @Reroute please can you elaborate \$\endgroup\$ – Simba N Jun 6 at 12:25
  • \$\begingroup\$ If the frequency is know, the capacitor will have an "impedance", in this circuit you can treat that equivilent to resistance, if rf = rin+Zcin you have a gain of 1. \$\endgroup\$ – Reroute Jun 6 at 12:27
  • \$\begingroup\$ @Reroute if I take the magnitude squared of Rf and equate it to the magnitude squared of Rin + Zcin, I get Rin = 1928? Unless I’ve done something wrong \$\endgroup\$ – Simba N Jun 6 at 12:41

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