SlewRate

Slew rate is the maximum rate at which an output signal can change over time, typically expressed for electronic amplifiers as the maximum dV/dt of the output, measured in volts per microsecond (V/µs). It is a key parameter for large-signal performance and can limit how quickly the device responds to fast inputs or abrupt changes in the input signal.

Slew rate is usually determined by the internal current available to charge or discharge load and compensation capacitors. In many voltage-feedback amplifiers with a Miller-compensation capacitor, the slew rate is roughly proportional to the charging current divided by the compensation capacitance (SR ≈ I/Cc). Different architectures, such as current-feedback amplifiers, use different mechanisms and thus have different SR limits. Factors such as supply voltage, bias currents, temperature, and device geometry also influence the slew rate.

Measurement typically involves applying a fast, large input step and observing the slope of the output during the transition. The region of linear output during the transition defines the slew rate. If the input step exceeds the device’s SR, the output will lag, producing distortion known as slew-induced distortion, extended settling times, and potential clipping or overshoot in some circuits.

Implications of a low or high slew rate depend on the application. High-speed data paths, video processing, and fast DAC/ADC interfaces demand high SR to avoid distortion, while extreme SR can increase power consumption and distortion in some analog stages. Designers balance SR with bandwidth, stability, noise, and power considerations.

Typical op-amp slew rates range from less than 1 V/µs to several hundred V/µs; high-speed devices can reach kilovolts per microsecond in specialized parts. See also bandwidth and settling time.