Wien Bridge Oscillator Calculator

A Wien Bridge oscillator uses an amplifier with positive and negative feedback networks to generate stable sine waves. The RC bridge network provides frequency-selective positive feedback at the resonant frequency, while negative feedback controls the amplitude and prevents distortion.

The oscillation frequency is f = 1 / (2πRC), where R is the resistance in ohms and C is the capacitance in farads. This formula assumes both resistors and both capacitors in the bridge network are equal.

For sustained oscillation, the Wien Bridge requires an amplifier gain of exactly 3 (or 9.54 dB). This compensates for the 1/3 attenuation of the RC feedback network at the resonant frequency.

Wien Bridge oscillators offer several advantages: they work at lower frequencies, don't require inductors (which are bulky and expensive), have better frequency stability, and produce very low distortion sine waves suitable for audio applications.

Amplitude control is achieved through automatic gain control (AGC) circuits, often using thermistors, FETs, or light bulbs in the negative feedback path. These components adjust their resistance based on the output amplitude to maintain stable oscillation.

Wien Bridge oscillators typically operate from very low frequencies (sub-Hz) up to about 1 MHz. They are most commonly used in audio frequency applications (20 Hz to 20 kHz) due to their excellent sine wave purity and low distortion.

Yes, electronic tuning can be achieved by using voltage-controlled resistors (VCRs) or varactor diodes in place of fixed components. FET-based voltage-controlled resistors are commonly used for this purpose in modern designs.

Distortion occurs when the gain is too high (causing clipping) or when the feedback network becomes non-linear. Proper amplitude limiting and maintaining the correct gain of 3 are essential for producing clean sine waves with minimal harmonic distortion.