Calculate the minimum required slew rate to avoid distortion for a sinusoidal signal.
Hz
kHz
MHz
Volts
Enter the peak amplitude (not peak-to-peak or RMS).
Please enter valid positive numbers for both fields.
Minimum Required Slew Rate
0.00 V/µs
or 0 Volts/second
How to Calculate Slew Rate of Op Amp
The Slew Rate (SR) of an operational amplifier is a critical specification that defines the maximum rate at which the output voltage can change per unit of time. Unlike bandwidth, which is a small-signal phenomenon, slew rate is a large-signal limitation. If your op amp cannot change its output voltage fast enough to keep up with the input signal, the output will become distorted, turning sine waves into triangular waves.
The Slew Rate Formula
While slew rate is defined in the time domain as ΔV/Δt, engineers most often need to calculate the slew rate required to reproduce a specific sinusoidal frequency without distortion. The formula for the minimum required slew rate for a sine wave is:
SR = 2 · π · f · Vpeak
Where:
SR: Slew Rate (typically measured in Volts per second, then converted to V/µs).
π (Pi): Approximately 3.14159.
f: The maximum frequency of the signal (in Hertz).
Vpeak: The peak voltage amplitude of the output signal (in Volts).
Step-by-Step Calculation Example
Let's calculate the slew rate required for an audio application. Suppose you need an op amp to output a signal with a maximum frequency of 20 kHz (the upper limit of human hearing) and a peak voltage of 10 Volts.
Identify the variables: Frequency (f) = 20,000 Hz
Peak Voltage (Vp) = 10 V
Apply the formula: SR = 2 × 3.14159 × 20,000 × 10
Calculate the result in Volts/second: SR = 1,256,637 V/s
Convert to Volts/microsecond (V/µs): Since specification sheets usually list SR in V/µs, divide the result by 1,000,000.
1,256,637 / 1,000,000 = 1.26 V/µs
In this example, you would need to select an operational amplifier with a slew rate specification of at least 1.26 V/µs to ensure the output remains undistorted at full power.
Why Slew Rate Matters
If you use an op amp with a slew rate lower than calculated, the device enters "slew rate limiting." The output slope becomes fixed at the device's maximum speed, failing to track the steeper parts of the sine wave. This results in significant non-linear distortion, known as Slew Induced Distortion (SID), and limits the Full Power Bandwidth of the amplifier.
function calculateSlewRate() {
// 1. Get Input Elements by ID
var freqInput = document.getElementById("inputFrequency");
var freqUnit = document.getElementById("selectFreqUnit");
var voltInput = document.getElementById("inputPeakVoltage");
var resultBox = document.getElementById("resultBox");
var resultDisplay = document.getElementById("resultValue");
var resultRaw = document.getElementById("resultRaw");
var errorDisplay = document.getElementById("errorDisplay");
// 2. Parse values
var f = parseFloat(freqInput.value);
var unitMultiplier = parseFloat(freqUnit.value);
var v = parseFloat(voltInput.value);
// 3. Validation Logic
if (isNaN(f) || isNaN(v) || f < 0 || v < 0) {
errorDisplay.style.display = "block";
resultBox.style.display = "none";
return;
}
// Hide error if valid
errorDisplay.style.display = "none";
// 4. Calculate Frequency in Hz
var frequencyHz = f * unitMultiplier;
// 5. Calculate Slew Rate (Volts per Second)
// Formula: SR = 2 * PI * f * Vpeak
var srVoltsPerSec = 2 * Math.PI * frequencyHz * v;
// 6. Convert to Volts per Microsecond (V/µs)
// 1 second = 1,000,000 microseconds
var srVoltsPerMicro = srVoltsPerSec / 1000000;
// 7. Format results
// Use meaningful formatting (2 decimal places for V/us)
var formattedResult = srVoltsPerMicro.toFixed(3) + " V/µs";
// Format raw number with commas for readability
var formattedRaw = Math.round(srVoltsPerSec).toLocaleString();
// 8. Update DOM
resultDisplay.innerHTML = formattedResult;
resultRaw.innerHTML = formattedRaw;
resultBox.style.display = "block";
}