Confused over PLL lock range, pull out range, pull in range.

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Bryan79

Joined: 17 Oct 2004
Posts: 15

02 Feb 2006 16:00 pll lock range

I am a bit confused over these PLL terminologies.

This is what I get.

Lock range: Maximum initial frequency offset which PLL acquire lock without cycle slips (in a single beat between reference signal and feedback signal)

Pull in range: Maximum initial frequency offset which PLL eventually acquire lock but with cycle slips. It is the largest value of offset for which the loop can still lock/pull-in, even with many cycle slips. If offset greater than pull in range, then the loop cannot acquire lock.

Pull out range: The pull-out range is that frequency step which causes a PLL to fall out lock if applied to the reference input of the PLL. The PLL may acquire lock again through a slow pull-in process.

Hold range: When PLL is phase-locked, it is the maximum frequency range in which frequency of the input reference signal can slowly be pulled away from the free running frequency of VCO but PLL still maintain phase-locked condition. It is static stability limit.

lock range < pull out range < pull in range < hold range

Question:

1. What happens if the reference signal offset frequency exceed lock range, but smaller than pull out range?

2. Any idea how to simulate the above terms, given I have formulas to calculate each of them?

Thanks.

Added after 5 hours 31 minutes:

I think I have found a very good document that explains these 4 terms (at pg 7, Cool