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Op-Amp Slew Rate & Full-Power Bandwidth

Calculate op-amp full-power bandwidth from slew rate and signal amplitude, and verify the op-amp can handle your signal without slew-rate distortion.

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Formula

FPBW=SR/(2π×Vpeak)FPBW = SR / (2π × V_peak)
SR— Slew rate (V/μs)
V_peak— Peak output voltage (V)

How It Works

Op-amp slew rate calculator computes the full-power bandwidth (FPBW) and minimum slew rate requirements — essential for audio amplifier design, video circuits, and high-frequency signal processing. Analog designers, audio engineers, and RF front-end designers use this to prevent slew-induced distortion in large-signal applications. Per Horowitz & Hill 'Art of Electronics' (3rd ed., p.239), slew rate (SR) is the maximum dV/dt the output can achieve, typically 0.5-100 V/μs for general-purpose op-amps. The relationship SR_min = 2πfV_peak (V/μs when f is in MHz and V in volts) determines whether an op-amp can reproduce a full-amplitude sine wave without distortion. Exceeding the slew rate limit causes triangular waveform distortion, adding odd harmonics that sound harsh in audio applications.

Worked Example

Verify NE5532 (SR = 9 V/μs) suitability for professional audio with ±15V supplies and 20kHz bandwidth. Maximum undistorted output: V_peak = 13.5V (90% of rail). Calculate SR_min = 2π × 20kHz × 13.5V / 10⁶ = 1.70 V/μs. Margin = 9/1.70 = 5.3× (adequate for audio transients). Calculate FPBW = SR/(2π × V_peak) = 9×10⁶/(2π × 13.5) = 106kHz. The NE5532 can reproduce full-amplitude signals up to 106kHz without slew limiting. For comparison, LM358 (SR = 0.5 V/μs) has FPBW = 5.9kHz at 13.5V — unsuitable for high-fidelity audio above moderate volumes.

Practical Tips

  • ✓For audio (20kHz, ±12V): SR > 2V/μs minimum; SR > 5V/μs recommended. NE5532 (9V/μs), OPA2134 (20V/μs), and LME49720 (20V/μs) are proven choices per Texas Instruments audio guide
  • ✓Video op-amps (AD8061, OPA695) provide SR > 300V/μs for high-speed applications — required for 1Vpp at frequencies above 50MHz
  • ✓Slew-rate distortion sounds distinctly harsh compared to soft clipping — measure with oscilloscope at 20kHz if distortion sounds 'grainy' at high volumes

Common Mistakes

  • ✗Confusing slew rate with gain-bandwidth — GBW limits small-signal bandwidth; SR limits large-signal bandwidth. An op-amp can have high GBW but low SR (e.g., LM358: 1MHz GBW, 0.5V/μs SR)
  • ✗Ignoring output swing requirements — SR requirement scales linearly with peak voltage; 10V swing requires 2× the SR of 5V swing at the same frequency
  • ✗Selecting op-amp with SR exactly at SR_min — transients and harmonics require instantaneous slew rates exceeding the fundamental; design for SR > 3× SR_min

Frequently Asked Questions

SR_min = 2π × 20kHz × 12V / 10⁶ = 1.51 V/μs. With 2× safety margin: SR > 3V/μs. Most modern audio op-amps (NE5532: 9V/μs, TL072: 13V/μs, OPA2134: 20V/μs) exceed this by 3-10×, providing headroom for transients.
Yes — reconstruction filter output may have fast transients requiring SR > 10V/μs even for audio frequencies. NE5532 (9V/μs) is marginal; OPA2134 (20V/μs) or LME49720 (20V/μs) are preferred for DAC I/V conversion per ESS Technology application notes.
Below slew limit: THD is set by open-loop distortion (~0.001% for quality op-amps). Near slew limit: 'soft' slew limiting increases THD to 0.1-1%. Above slew limit: severe triangular clipping causes THD > 10%. For THD < 0.01% at 20kHz, design for SR > 5× SR_min.
FPBW = SR/(2π × V_peak). An op-amp with SR = 10V/μs and 10V peak output has FPBW = 10×10⁶/(2π × 10) = 159kHz. This is the maximum frequency for undistorted full-amplitude sine waves. At lower amplitudes, usable bandwidth extends higher: half amplitude doubles FPBW.

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