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oscillator basic

Can anyone give help. here.. I have an elementry question on oscillator theory. The oscillation criterion from a TI journal says the phase shift feedback from the output to the input is 180 but whereas many books tell the total phase shift of the whole circuit should be 0 deg or n360..

i got confused on the subject

The TI journal (talks about Ab = 1 /_ -180deg)

formatting link

Books talks about total phase shift is 360 deg Robert J. Matthys, CRYSTAL OSCILLATOR CIRCUITS, Krieger publishing company, malabar florida

Confused. Em7

Reply to
E Minor 7
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"The 180 degree phase shift criterion applies to negative feedback systems, and 0 (or 360) degree phase shift applies to positive feedback systems."

The inversion at the -ve summer input supplies the other 180 degrees.

Reply to
Andrew Holme

hi when you give a phase shift of 180 the circuit behaves as a amplifier and a 360 gives a oscillator

Reply to
prad

thanks, but why peoples say when ABeta = -180, gives you the divider is

0 and the circuit becomes ocsillate ( unstable)
Reply to
E Minor 7

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