Due to the non-linearity of the active device characteristic, harmonics of the fundamental are created which are fed back and gets mixed to create IMP that introduce phase distortion at the oscillation frequency (say 2*wo-wo=wo falls at the original fundamental at altered phase) that results in frequency shift. Frequency stability problems like these dont get diluted by buffer stages (though they prevent phase distortion from transient load changes or non-linear load capacitances).
But won't the harmonics be filtered out the by the crystal which in itself acts like a narrow band filter?
Due to the non-linearity of the active device characteristic, harmonics of the fundamental are created which are fed back and gets mixed to create IMP that introduce phase distortion at the oscillation frequency (say 2*wo-wo=wo falls at the original fundamental at altered phase) that results in frequency shift. Frequency stability problems like these dont get diluted by buffer stages (though they prevent phase distortion from transient load changes or non-linear load capacitances).
Vittoz cites this as one of the major reasons to go for amplitude regulation. With amplitude regulation these effects can be reduced greatly.
To ensure that this happens, you can run PSS on the oscillator without AGC (allow harmonics->near square wave output) and with AGC (sine-wave output) and compare their phase noise performance
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?