Slew rate refers to how quickly the output voltage of an operational amplifier (op amp) can change.
Understanding Slew Rate
Based on the provided information, slew rate is specifically defined as:
- The maximum rate of change of an op amp's output voltage.
This characteristic indicates the speed limit at which an op amp's output can respond to a large, rapid change at its input. It's a fundamental limitation on the op amp's performance, particularly when dealing with high-frequency signals or large signal swings.
Units of Slew Rate
The slew rate is typically expressed in:
- Volts per microsecond (V/µs).
For example, an op amp with a slew rate of 10 V/µs means its output voltage cannot change faster than 10 volts every microsecond, regardless of how fast the input changes.
How Slew Rate is Measured
The measurement process for slew rate involves testing the op amp's response to a significant input change:
- Apply a large signal step: A substantial step voltage, such as 1V, is applied to the op amp's input. This causes the output voltage to ideally change rapidly.
- Measure output change: The rate of change is then measured on the output signal.
- Focus on a specific range: This measurement is specifically taken as the time it takes for the output signal's amplitude to change from 10% to 90% of its final value.
This measurement method captures the op amp's speed limit under large-signal conditions, distinguishing slew rate from the small-signal bandwidth response.
Slew rate is a crucial parameter when selecting op amps for applications requiring fast output voltage changes, such as pulse amplification or high-frequency signal processing.
