Op-amp oscillators
Op-amp oscillators with circuit equations and operating-limit checks.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Wien bridge: f0 = 1/(2πRC); amplifier gain threshold = 3
Unbuffered three-section RC phase shift: f0 = 1/(2πRC√6); amplifier gain magnitude ≥ 29
Relaxation oscillator: f = 1/[2RC ln((1+β)/(1−β))]
Assumptions
- Wien model uses equal R/C bridge arms. Phase-shift model is the classic unbuffered equal-component three-section ladder with the standard ideal loading assumption. Startup requires excess loop gain; a separate amplitude-control mechanism is needed for low-distortion sine oscillation. Relaxation model assumes symmetric instantaneous output switching and negligible comparator delay.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Oscillator
- wien
- Timing resistor
- 10000 Ω
- Timing capacitor
- 1e-8 F
- Relaxation feedback fraction
- 0.333333
- Symmetric output swing
- 10 V
Results
- Oscillation frequency
- 1591.55 Hz
- Ideal gain threshold
- 3
- Period
- 0.000628319 s
- Relaxation threshold magnitude
- Not applicable V