Wien Bridge Gain Resistor
Rf = 2 · Rg (for Av = 3)
Quick answer
This calculator solves Rf = 2 × Rg (so Av = 1 + Rf/Rg = 3) for Feedback Resistor. With Ground Resistor 22 kΩ, the result is 44 kΩ. It solves in 2 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
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.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| Rf | Feedback Resistor | kΩ | mΩ, Ω, kΩ, MΩ |
| Rg | Ground Resistor | kΩ | mΩ, Ω, kΩ, MΩ |
Step by step
- 1. What you know: Ground Resistor 22 kΩ
- 2. The relation: Rf = 2 × Rg (so Av = 1 + Rf/Rg = 3)
- 3. Substitute: Rg = 22 kΩ
- 4. Result: Feedback Resistor = 44 kΩ
Nearest standard component values
| Series | Nearest value | Error |
|---|---|---|
| E12 | 47 kΩ | 6.8% |
| E24 | 43 kΩ | 2.3% |
Worked examples
Minimum range
Given: Ground Resistor 0.22 kΩ
Result: Feedback Resistor = 0.44 kΩ
Low range
Given: Ground Resistor 2.2 kΩ
Result: Feedback Resistor = 4.4 kΩ
Typical
Given: Ground Resistor 22 kΩ
Result: Feedback Resistor = 44 kΩ
High range
Given: Ground Resistor 0.22 MΩ
Result: Feedback Resistor = 0.44 MΩ
Maximum range
Given: Ground Resistor 2.2 MΩ
Result: Feedback Resistor = 4.4 MΩ
Solving for each variable
Solve for Feedback Resistor
Ground Resistor 0.22 kΩ → 0.44 kΩ
Solve for Ground Resistor
Feedback Resistor 100 Ω → 50 Ω
How Feedback Resistor changes with Ground Resistor
| Ground Resistor (input) | Feedback Resistor (result) |
|---|---|
| 2.2 kΩ | 4.4 kΩ |
| 5.5 kΩ | 11 kΩ |
| 11 kΩ | 22 kΩ |
| 16.5 kΩ | 33 kΩ |
| 22 kΩ | 44 kΩ |
| 33 kΩ | 66 kΩ |
| 44 kΩ | 88 kΩ |
| 88 kΩ | 0.176 MΩ |
| 154 kΩ | 0.308 MΩ |
| 0.22 MΩ | 0.44 MΩ |
The same result in other units
| Unit | Value |
|---|---|
| Ω | 44000 |
| kΩ | 44 |
| MΩ | 0.044 |
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<p><a href="https://vbatpower.com/formulas/wien-bridge-gain-resistor/">Wien Bridge Gain Resistor</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Wien Bridge Gain Resistor?
Use Rf = 2 × Rg (so Av = 1 + Rf/Rg = 3). With Ground Resistor 22 kΩ, Feedback Resistor works out to 44 kΩ.
What is the formula for Wien Bridge Gain Resistor?
The formula is 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.
How do you find Ground Resistor when you know the other values?
Rearrange for Ground Resistor: with Feedback Resistor 100 Ω, Ground Resistor is 50 Ω.
What units does Wien Bridge Gain Resistor use?
Feedback Resistor is shown in Ω, kΩ, MΩ. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
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