What is the formula for Wien Bridge Gain Resistor?

The Wien Bridge Gain Resistor formula is Rf = 2 × Rg (so Av = 1 + Rf/Rg = 3), where Rf—Feedback resistor (Ω); Rg—Resistor from inverting input to ground (Ω).

Wien Bridge Gain Resistor

Q: How do you calculate Wien Bridge Gain Resistor?

Use the formula Rf = 2 × Rg (so Av = 1 + Rf/Rg = 3). A Wien bridge oscillator’s amplifier must provide a voltage gain of exactly 3 to overcome the network’s 1/3 attenuation. Enter the values you know in the calculator above and it solves for the remaining variable.

Rf = 2 · Rg (for Av = 3)

Calculator

Feedback Resistor

Ground Resistor

Result

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Formula

Rf = 2 × Rg (so Av = 1 + Rf/Rg = 3)

Description

A Wien bridge oscillator’s amplifier must provide a voltage gain of exactly 3 to overcome the network’s 1/3 attenuation. For a non-inverting amplifier (Av = 1 + Rf/Rg), this means the feedback resistor must be twice the grounded resistor. In practice the gain is set slightly above 3 and an amplitude-limiting element pulls it back to 3 for stable oscillation.

Variables

Rf — Feedback resistor (Ω)
Rg — Resistor from inverting input to ground (Ω)

Practical Notes

Set Rf just over 2·Rg and add a nonlinear element (lamp/JFET/diode limiter) so the effective gain settles at 3, giving stable low-distortion output.

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