There are two feedback loops in the Wien-bridge oscillator. What is the purpose of each?

The Wien-bridge oscillator is a type of electronic oscillator that generates sine waves. It can generate a large range of frequencies. The oscillator is based on a bridge circuit originally developed by Max Wien in 1891 for the measurement of impedances.

The Wien-bridge oscillator includes two feedback loops: a positive feedback loop and a negative feedback loop.

1. Positive Feedback Loop: The purpose of the positive feedback loop is to sustain oscillations. This is because, in an oscillator, the output is fed back to the input in phase. This means that the feedback signal adds to the input signal, reinforcing it and keeping the oscillation going.

2. Negative Feedback Loop: The purpose of the negative feedback loop is to stabilize the amplitude of the oscillations. This is achieved by feeding back a portion of the output to the input but in an opposite phase. This means that the feedback signal subtracts from the input signal, preventing the amplitude of the oscillation from growing out of control.

In summary, the positive feedback loop ensures that the oscillator continues to oscillate, while the negative feedback loop keeps the amplitude of the oscillations stable.