How to Measure Amplifier Slew Rate

+ Advanced Benchtop Waveform and Function Generator

Separate Stimulus Limits From Amplifier Response

When an amplifier is driven by a fast, large-signal voltage step, its output may not follow the input edge immediately. Instead, the output can transition at a nearly constant maximum slope determined by the amplifier’s slew-rate limit. The measurement challenge is to distinguish this large-signal behavior from edge-rate limitations, loading, probing effects, or insufficient oscilloscope bandwidth in the test setup.

The test requires a square-wave source with a transition faster than the expected amplifier response, a sufficiently fast oscilloscope, and low-capacitance probing at the input and output. A low repetition rate allows each transition to settle before the next edge. Slew rate is calculated from the linear portion of each output transition as change in voltage divided by change in time, with rising and falling edges evaluated separately.

Amplifier Slew Rate Measurement Solution

Perform the test by driving the amplifier with a low-frequency square wave whose measured input transition is faster than the expected output transition, while an oscilloscope captures the input and output simultaneously. Advanced Benchtop Waveform and Function Generators provide a repeatable 30 MHz, two-channel stimulus source with point-by-point arbitrary waveform generation. Configure amplitude, offset, source termination, and repetition rate to place the amplifier in its intended large-signal operating region and allow full settling between edges. Measure the linear portion of each output transition, calculate positive and negative slew rate as ΔV/Δt, and verify that the source edge, probes, and oscilloscope bandwidth do not limit the result.

Get Quote