Op-Amp Slew Rate Calculator

Slew rate limiting is a consequence of the internal "Miller" compensation capacitor used in nearly every general-purpose op-amp since Widlar\'s µA741 (1968). The compensation cap stabilizes the feedback loop against high-frequency oscillation, but it must be charged and discharged by the input differential stage\'s tail current. Once the input differential voltage exceeds a few hundred millivolts, the tail current is entirely redirected into charging the cap, and the output rate-of-change saturates at dV/dt = I_tail / C_c — the slew rate.

Early designers assumed op-amps were small-signal linear, which they are — up to the slew limit. Jim Solomon (National Semiconductor) and Bob Widlar developed faster tail-current designs in the 1970s that achieved slew rates of 10–50 V/µs. Decompensated op-amps (LM301 with user-added compensation) let the designer trade stability for speed. Current-feedback op-amps, commercialized by Comlinear and Elantec in the 1980s, bypass the traditional slew mechanism entirely and can exceed 2000 V/µs for video and RF applications.

The full-power bandwidth formula f_max = SR / (2π·V_pk) follows from differentiating the sine wave V(t) = V_pk·sin(2πft), whose maximum dV/dt is 2π·f·V_pk at the zero crossings. Above f_max, the op-amp can\'t keep up with the demanded slope and the output waveform turns from sinusoidal into triangular — easily audible as distortion on audio signals, easily visible on a scope as "cornered" sine peaks.

Enter the op-amp\'s slew rate (from the datasheet, typically in V/µs), the peak output voltage your application needs, and optionally a frequency to check against. The tool returns the full-power bandwidth f_max, the required SR at your input frequency, and whether the op-amp has enough slew headroom.

Slew rate is independent of gain-bandwidth product (GBW): an op-amp can have 10 MHz small-signal BW but only 20 kHz full-power BW if its slew rate is low. For audio (20 kHz full-scale sines), 1 V/µs per volt of peak output is the minimum; video needs 20–30 V/µs; RF and fast transient applications need hundreds to thousands. Everything runs client-side.