The Wien-bridge oscillator is a unique circuit because it generates an oscillatory output signal without having a sinusoidal input source. Instead, it uses capacitors with initial voltages to create the output. This circuit can be especially useful if connected to a voltage follower to de-couple the load from the source. ANS; A Wien bridge o
scillator produces sine waves. In order for the sine waves to maintain a steady amplitude, a positive feedback system is used with some sort of control to limit gain. In order for the positive feedback system to work, the waves being "fed back" to the amplifier have to be in phase with the waves being generated. Thus, you need a phase shift network to ensure that the phases of the waves match, which in the case of a positive feedback system means that the generated waves need to go through a 360o phase shift during the feedback process.