= Op amp differentiator
{title2=$V_{\rm out}=-RC\,dV_{\rm in}/dt$}
For an <ideal operational amplifier> with grounded non-inverting input, connect an input <capacitor> $C$ to the inverting input and a feedback <resistor> $R$ from output to that input. The <virtual ground> and <Kirchhoff's current law> give $C\dot V_{\rm in}=-V_{\rm out}/R$. The ideal response amplifies high-frequency noise, so practical differentiators restrict its operating band and maintain feedback stability.
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