Wien Bridge Oscillator with AGC and PLL

Gregory explains the circuit of a Wien Bridge Oscillator, that uses automatic gain control and a PLL architecture for amplitude and frequency stability.

The Wien bridge oscillator works by positive feedback excitation over a linear amplifier. Very high harmonic purity is accomplished by the passive feedback network and the linear operation.

Automatic gain control is need to sustain oscillation at a constant amplitude, preventing saturation or suppression of the signal.

The frequency stability of a normal Wien bridge oscillator is defined by the phase-slope of the feedback network. For this design, the desired output phase-noise improvement was accomplished by locking the linear oscillator in a PLL architecture.

Watch the video showing the circuit working:
   • THD - Total Harmonic Distortion  

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