Re: PLL locking problem

"John Larkin" <[EMAIL PROTECTED]> wrote in
message news:[EMAIL PROTECTED]
> On 2 Dec 2003 06:22:57 -0800, [EMAIL PROTECTED] (cici) wrote:
>
> >John Larkin <[EMAIL PROTECTED]> wrote in
message news:<[EMAIL PROTECTED]>...
> >> On 1 Dec 2003 08:48:36 -0800, [EMAIL PROTECTED] (cici) wrote:
> >>
> >> >My PLL can not lock. I am using an XOR as the PD, cross coupled VCO.
> >> >The control voltage is in the tuning voltage range of VCO. However, it
> >> >is an oscillation the same frequency of the output of the PD. When the
> >> >PLL is locked, the voltage should be a straight line. What can be the
> >> >problem? Thanks!
> >>
> >> Sounds maybe like a loop stability problem. I've built PLLs that were
> >> so unstable that they did all they could to run away from locking. If
> >> you don't know this stuff already, get a good book on PLL dynamics.
> >>
> >> Are you using a lowpass filter after the PD? Got any more details?
> >>
> >> John
> >
> >Yes, I am using a RC low pass filter, followed by a source follower.
>
> Try adding a small R in series with the C... that will damp an
> otherwise very ringy loop dynamic.
>
> John
>

Hmmm.

Excuse me but........ didn't you suggest that DM, or some other, was in the
realms of suck it and see coz you thought you were so ded clev at doing the
job proper?

And then you suggest adding a small R in series with the C to deal with a
ringy loop dynamic.

That is a big fucking schnort......

No offence meant but....... c'mon.

DNA