High slew rate is needed for many systems like waveform generation, driver circuits, and more. Insufficient slew rate may result in distortion of the output, namely long rise times or nonlinearity. It is important to know that the slew rate performance of your amplifier can be significantly reduced depending on the application circuit. This is especially true for voltage feedback amplifiers with no internal slew boosting circuitry. The slew rate of a voltage feedback op-amp is dependent on the voltage across its inputs, so a small input step could result in a fraction of the data sheet’s slew rate value. The slew-rate dependency on input voltage means that high gain applications will often suffer from significantly reduced slew rate performance.

However, current feedback amplifiers do not have the same constraint. Current feedback architecture provides not only a higher slew rate, but also one that is relatively constant across different input steps. This document demonstrates the difference in performance slew-rate performance at high gain between the voltage-feedback OPA690 and current feedback OPA695.