Op Amp Slew Rate Calculator

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Op Amp Slew Rate Calculator

Hz kHz MHz

Calculation Results:

Required Slew Rate: 0 V/µs

To avoid distortion, choose an Op Amp with a Slew Rate higher than this value.

What is Op Amp Slew Rate?

The slew rate is a critical parameter in operational amplifiers (Op Amps) that defines the maximum rate of change of the output voltage per unit of time. It is typically expressed in Volts per microsecond (V/µs). If the input signal changes faster than the Op Amp's slew rate can handle, the output becomes distorted, often turning a smooth sine wave into a triangular shape.

The Slew Rate Formula

To calculate the minimum required slew rate for a sine wave signal without distortion, we use the following formula derived from the derivative of a sine function:

SR = 2 × π × f × Vp / 1,000,000

  • SR: Slew Rate in V/µs
  • f: Frequency of the signal in Hertz (Hz)
  • Vp: Peak output voltage (the maximum amplitude from zero)
  • π: Approximately 3.14159

Why Does Slew Rate Matter?

In high-frequency applications or high-voltage swing scenarios, the internal compensation capacitors of the Op Amp limit how fast the output stage can slew. If you exceed this limit:

  1. Signal Distortion: Sine waves appear clipped or "triangulated."
  2. Reduced Bandwidth: The "Full Power Bandwidth" is directly limited by the slew rate.
  3. Phase Errors: Significant phase shifts can occur, potentially destabilizing feedback loops.

Example Calculation

Suppose you have an audio signal with a peak voltage of 10V and a maximum frequency of 20 kHz. To ensure the signal remains clean, the required slew rate would be:

SR = 2 × 3.14159 × 20,000 Hz × 10V = 1,256,637 V/s
Divide by 1,000,000 to get V/µs = 1.26 V/µs.

In this case, an Op Amp like the classic LM741 (0.5 V/µs) would fail, while a TL081 (13 V/µs) would easily handle the signal.

function calculateSlewRate() { var peakV = document.getElementById("peakVoltage").value; var freq = document.getElementById("frequency").value; var unit = document.getElementById("freqUnit").value; var resultDiv = document.getElementById("sr-result"); var displaySR = document.getElementById("val-sr"); if (peakV === "" || freq === "" || peakV <= 0 || freq <= 0) { alert("Please enter valid positive numbers for both voltage and frequency."); return; } var f_hz = parseFloat(freq) * parseFloat(unit); var v_p = parseFloat(peakV); // Formula: SR = 2 * pi * f * Vp // To get V/µs, we divide the V/s result by 1,000,000 var slewRate = (2 * Math.PI * f_hz * v_p) / 1000000; displaySR.innerText = slewRate.toFixed(4); resultDiv.style.display = "block"; // Scroll to result smoothly resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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