BillH
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Posts: 7
San Diego
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Depending on what specs you are trying to meet the loop bandwidth is either set to insure stability, minimize reference spurs, minimize integrated phase noise, or minimize contribution of Delta-Sigma Modulation noise.
In my experience, mostly working on PLL's in communication systems, the loop bandwidth is usually set to optimize integrated phase noise. This bandwidth usually tends to be close the offset frequency for which the contribution from the PLL noise sources (ref, PFD, CP, divider, loop filter) which tend to be flat wrt offset frequency is equal to the VCO noise contribution (which tends to be dropping 20dB/dec wrt offset frequency).
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