Enter your Resistor Value, Capacitor Value, Frequency, and Pulse Time into the Differentiator Circuit Calculator, then hit Calculate to get your Time Constant (τ), Cutoff Frequency, Period, and the critical Pulse Time / Time Constant ratio that tells you how well your circuit actually differentiates the signal.
Calculated Value
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Time Constant (τ)
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Cutoff Frequency
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Period
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Pulse Time / Time Constant
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A differentiator circuit produces an output voltage proportional to the rate of change of the input voltage. It's used for edge detection, converting sine waves to cosine waves, and changing triangle waves into square waves.
The RC differentiator uses a capacitor in series with the input and a resistor to ground. The capacitor blocks DC and passes changing voltages, while the resistor provides the output path. The output is proportional to the derivative of the input.
The time constant (τ) equals R × C and determines the circuit's response speed. For optimal differentiation, the pulse time should be much longer than the time constant (typically 5τ or more).
Differentiators amplify high-frequency noise because they have increasing gain with frequency. This makes them susceptible to instability and noise, often requiring additional components for stabilization.
RC differentiators are passive circuits with limited gain and loading effects. Op-amp differentiators provide active amplification, better isolation, and adjustable gain but are more complex and prone to instability.
Choose values so the time constant (RC) is much smaller than the input signal period for good differentiation. Typical values range from 1kΩ-100kΩ for resistors and 1nF-1µF for capacitors.
If the pulse time is less than 5 times the time constant, the circuit won't fully differentiate the signal, resulting in poor pulse shaping and reduced performance.
Yes, differentiators are excellent for square wave inputs, producing sharp spikes at the rising and falling edges. This is commonly used for edge detection and trigger generation.