Question

Which of the following signals are generated by Wien-bridge oscillators?

• A. Square wave
• B. Sine wave
• C. Triangular wave
• D. Pulse wave

Hint:

RC feedback oscillators (like Wien-bridge and Phase-Shift oscillators) are classic linear circuits designed to generate pure sine waves.
Square, triangular, and pulse waves are generated by non-linear astable multivibrators or function generators.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks for the waveform shape of the electrical signal produced by a Wien-bridge oscillator.

Step 2: Detailed Explanation:

• A Wien-bridge oscillator is a type of RC feedback oscillator.

• It uses a lead-lag RC network (Wien bridge) in its positive feedback path to select a specific oscillation frequency, and negative feedback to stabilize the output amplitude.

• Because of its highly selective bandpass filtering characteristics at the resonant frequency $f = \frac{1}{2\pi RC}$, it filters out all higher-order harmonics.

• As a result, the circuit generates a very clean, low-distortion, stable sinusoidal output waveform.

• It is widely used as a standard audio-frequency signal generator ($10\text{ Hz to }1\text{ MHz}$) to produce high-quality sine waves.

Step 3: Final Answer:
Wien-bridge oscillators generate sine waves.