Calculate Slew Rate, Full Power Bandwidth, or Peak Voltage
Minimum Slew Rate Required
Maximum Frequency (Bandwidth)
Maximum Peak Voltage
Hz
kHz
MHz
Volts
V/µs
Result
0
function updateFormVisibility() {
var type = document.getElementById('calculationType').value;
var groupFreq = document.getElementById('group-freq');
var groupVolt = document.getElementById('group-volt');
var groupSlew = document.getElementById('group-slew');
var resultBox = document.getElementById('resultBox');
// Reset display
groupFreq.style.display = 'block';
groupVolt.style.display = 'block';
groupSlew.style.display = 'block';
resultBox.style.display = 'none';
// Hide the one we are calculating
if (type === 'slew') {
groupSlew.style.display = 'none';
} else if (type === 'freq') {
groupFreq.style.display = 'none';
} else if (type === 'voltage') {
groupVolt.style.display = 'none';
}
}
function calculateSlewLogic() {
var type = document.getElementById('calculationType').value;
var freqInput = document.getElementById('frequency').value;
var freqUnit = document.getElementById('freqUnit').value;
var voltInput = document.getElementById('voltage').value;
var slewInput = document.getElementById('slewRate').value;
var resultBox = document.getElementById('resultBox');
var resultValue = document.getElementById('resultValue');
var resultLabel = document.getElementById('resultLabel');
var resultExplanation = document.getElementById('resultExplanation');
// Constants
var pi = Math.PI;
// Parse Inputs
var freqBase = parseFloat(freqInput) * parseFloat(freqUnit); // Convert to Hz
var voltage = parseFloat(voltInput); // Volts
var slewRate = parseFloat(slewInput); // V/µs
var result = 0;
if (type === 'slew') {
// Calculate Slew Rate
// Formula: SR = 2 * pi * f * Vp
// Result comes out in V/s, need to convert to V/µs (divide by 1,000,000)
if (isNaN(freqBase) || isNaN(voltage) || freqBase <= 0 || voltage <= 0) {
alert("Please enter valid positive values for Frequency and Voltage.");
return;
}
var srVoltsPerSecond = 2 * pi * freqBase * voltage;
var srVoltsPerMicro = srVoltsPerSecond / 1000000;
resultLabel.innerHTML = "Required Slew Rate";
resultValue.innerHTML = srVoltsPerMicro.toFixed(4) + " V/µs";
resultExplanation.innerHTML = "This represents the minimum speed the Op-Amp output must change to avoid distortion at " + voltage + "V peak.";
}
else if (type === 'freq') {
// Calculate Frequency (Full Power Bandwidth)
// Formula: f = SR / (2 * pi * Vp)
// Slew Rate input is V/µs, convert to V/s first (multiply by 1,000,000)
if (isNaN(slewRate) || isNaN(voltage) || slewRate <= 0 || voltage 1000000) {
displayFreq = maxFreqHz / 1000000;
unit = "MHz";
} else if (maxFreqHz > 1000) {
displayFreq = maxFreqHz / 1000;
unit = "kHz";
}
resultLabel.innerHTML = "Maximum Frequency (Bandwidth)";
resultValue.innerHTML = displayFreq.toFixed(2) + " " + unit;
resultExplanation.innerHTML = "Above this frequency, the Op-Amp will be slew-rate limited and the output will distort into a triangle wave.";
}
else if (type === 'voltage') {
// Calculate Max Voltage
// Formula: Vp = SR / (2 * pi * f)
if (isNaN(slewRate) || isNaN(freqBase) || slewRate <= 0 || freqBase <= 0) {
alert("Please enter valid positive values for Slew Rate and Frequency.");
return;
}
var srVoltsPerSecond = slewRate * 1000000;
var maxVolt = srVoltsPerSecond / (2 * pi * freqBase);
resultLabel.innerHTML = "Maximum Peak Voltage";
resultValue.innerHTML = maxVolt.toFixed(2) + " V";
resultExplanation.innerHTML = "The maximum peak amplitude the Op-Amp can output at this frequency without slew-induced distortion.";
}
resultBox.style.display = 'block';
}
// Initialize visibility on load
updateFormVisibility();
What is Slew Rate?
In electronics, the Slew Rate (SR) of an operational amplifier (op-amp) is defined as the maximum rate of change of the output voltage per unit of time. It acts as a "speed limit" for the op-amp. If the input signal demands the output voltage to change faster than the slew rate allows, the output signal will undergo distortion.
Slew rate is typically measured in Volts per microsecond (V/µs). It is a critical parameter when working with high-frequency signals or large amplitude signals.
Slew Rate Formula
For a sinusoidal signal, the slew rate required to reproduce the signal without distortion is determined by the signal's frequency and its peak voltage amplitude. The relationship is governed by the following equation:
SR = 2 · π · f · Vp
Where:
SR: Slew Rate (measured in Volts per second, usually converted to V/µs).
f: Frequency of the sine wave in Hertz (Hz).
Vp: Peak Voltage of the sine wave (Volts).
Note: If you are using peak-to-peak voltage (Vpp), remember that Vp = Vpp / 2.
Why Does Slew Rate Matter?
If an op-amp tries to output a sine wave with a frequency and amplitude that requires a slope steeper than its Slew Rate specification, the output will not look like a sine wave. Instead, it will look triangular. This is known as slew-induced distortion.
This calculator helps engineers determine:
Required Slew Rate: What spec op-amp do you need for a specific signal?
Full Power Bandwidth: What is the maximum frequency a specific op-amp can handle at a given voltage?
Max Amplitude: How large can the signal be at a specific frequency before distorting?
Example Calculation
Suppose you need to amplify a signal with a frequency of 20 kHz and a peak amplitude of 10 Volts.
Convert frequency to Hz: 20 kHz = 20,000 Hz.
Apply the formula: SR = 2 * 3.14159 * 20,000 * 10.
SR = 1,256,637 Volts/second.
Convert to V/µs: 1,256,637 / 1,000,000 = 1.26 V/µs.
Therefore, you would need an op-amp with a slew rate of at least 1.26 V/µs to avoid distortion.