Integrator Circuit Calculator

The op-amp integrator uses a capacitor in the feedback loop instead of a resistor. As current flows through the input resistor, it charges the capacitor, creating an output voltage proportional to the integral of the input voltage over time.

The time constant (τ) equals R × C and determines how quickly the circuit responds. It's measured in seconds and represents the time needed for the capacitor to charge to about 63% of its final value.

For optimal integration, the pulse time should be about 5 times the time constant (t1 = 5τ). This ensures the capacitor has enough time to charge properly and produce a good ramp output.

A feedback resistor prevents DC saturation caused by input offset voltage and bias currents. Without it, the integrator may saturate to the supply rails, but it limits the low-frequency integration range.

An ideal integrator has infinite gain at DC and integrates down to 0 Hz. A practical integrator includes a feedback resistor for stability, which limits the low-frequency response and creates a finite DC gain.

Choose the capacitor based on your desired time constant and available resistor values. Smaller capacitors work better at high frequencies, while larger capacitors are better for low-frequency integration and longer time constants.

If τ is too small compared to the input pulse width, the integration will be incomplete, resulting in poor waveform shaping. The output may not reach the expected ramp voltage before the input changes.

Yes, integrators work with AC signals and are commonly used in analog computers, waveform generators, and filter circuits. The output will be the mathematical integral of the input waveform, shifted in phase by 90 degrees.