The XOR phase comparator is without feed-back and that simply means no
dead-zone. This is consistent with literature on XOR PDs.
It will of course have non-linearity which is improving with speed of
the process technology. A 74HC4046 will be better than a CD4046.
BUT the low-frequency noise is inversely proportional to channel-length
of the used MOSFETs. So for time-nuts interests a slower CD4046 can be
better.
The other 4046 phase comparators are made of flip-flops where the
dead-zone is proportional to gate-delay.
For ultimate performance one have to use a classical DRM.
- Henry
Brian Justin schrieb:
Not yet, but I guess I will now!
Thanks!
-Brian
----- Original Message ----
From: Orin Eman <orin.e...@gmail.com>
To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Sent: Wed, January 4, 2012 12:59:12 PM
Subject: Re: [time-nuts] crunching numbers from XOR phase detector
Have you tried the 74HCT9046? They claim no dead zone. Note - seems to be
HCT only.
Orin.
On Wed, Jan 4, 2012 at 9:32 AM, Brian Justin <wa1...@att.net> wrote:
Be very careful of the FPD in the 4046. It has a dead-zone when the phase
error
is at or very close to zero. Some versions of the chip claim to have
"improved"
that dead-zone. But it's still there to some degree, at least in all the
versions I have tried.
-Brian, WA1ZMS
--
ehydra.dyndns.info
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
