PLL Digital Loop Filter
I'm trying to understand how to design and analyze the loop filters in a
digital PLL. Specifically, because of digital processing delays, the phase
offset measured at time t will only produce a change on the VCXO input at
time t+T, where T is the sampling period of the digital loop.
I've found plenty of texts describing analog loop filters. Are there any
recommendations for digital loop filter PLL design?
Thanks,
James
In message CA+XcqA7UgGn2Qq8b+f+fK3qSiDM3bADWtYQSyO3=sbXUJw5bkw@mail.gmail.com
, James Peroulas writes:
I've found plenty of texts describing analog loop filters. Are there any
recommendations for digital loop filter PLL design?
This may help:
http://phk.freebsd.dk/time/20141018.html
--
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phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
On Mon, 20 Mar 2017 21:32:28 -0700
James Peroulas james@peroulas.com wrote:
I'm trying to understand how to design and analyze the loop filters in a
digital PLL. Specifically, because of digital processing delays, the phase
offset measured at time t will only produce a change on the VCXO input at
time t+T, where T is the sampling period of the digital loop.
You have the same delays in analog filters as well. As a rule of thumb
you can assume that the delays are in the same order of magnitude as
with the equivalent analog filters, not accounting for the delays due to
pre- and post-processing of the signal.
The analysis of digital PLLs works the same as with analog ones, you
just exchange the Laplace transform with the Z-transform. You can add
arbitrary delays due to pre/post-processing as a simple multiplication
by 1/z for each clock cycle of delay.
I've found plenty of texts describing analog loop filters. Are there any
recommendations for digital loop filter PLL design?
The PLL book by Best contains two chapters on how to design digital PLLs.
I can also recommend "Understanding digital signal processing" by Lyons,
which is a very hands-on description how to do filters and perform other
signal processing tasks.
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
Have to say a search for PLL book by Best generates lots of stuff. None of
it about PLLs. Better hint please? I think Lyons may be a bit better.
Regards
Paul
WB8TSL
On Tue, Mar 21, 2017 at 7:39 AM, Attila Kinali attila@kinali.ch wrote:
On Mon, 20 Mar 2017 21:32:28 -0700
James Peroulas james@peroulas.com wrote:
I'm trying to understand how to design and analyze the loop filters in a
digital PLL. Specifically, because of digital processing delays, the
phase
offset measured at time t will only produce a change on the VCXO input at
time t+T, where T is the sampling period of the digital loop.
You have the same delays in analog filters as well. As a rule of thumb
you can assume that the delays are in the same order of magnitude as
with the equivalent analog filters, not accounting for the delays due to
pre- and post-processing of the signal.
The analysis of digital PLLs works the same as with analog ones, you
just exchange the Laplace transform with the Z-transform. You can add
arbitrary delays due to pre/post-processing as a simple multiplication
by 1/z for each clock cycle of delay.
I've found plenty of texts describing analog loop filters. Are there any
recommendations for digital loop filter PLL design?
The PLL book by Best contains two chapters on how to design digital PLLs.
I can also recommend "Understanding digital signal processing" by Lyons,
which is a very hands-on description how to do filters and perform other
signal processing tasks.
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
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and follow the instructions there.
it is tempting to use digital loop filter for PLL if a very low
bandwidth is required, but with the large time constant is a problem ;
the VCO will change it's frequency despite the tuning voltage remains
constant and that is not so simple to model.
73
KJ6UHN
Alex
On 3/21/2017 4:39 AM, Attila Kinali wrote:
On Mon, 20 Mar 2017 21:32:28 -0700
James Peroulas james@peroulas.com wrote:
I'm trying to understand how to design and analyze the loop filters in a
digital PLL. Specifically, because of digital processing delays, the phase
offset measured at time t will only produce a change on the VCXO input at
time t+T, where T is the sampling period of the digital loop.
You have the same delays in analog filters as well. As a rule of thumb
you can assume that the delays are in the same order of magnitude as
with the equivalent analog filters, not accounting for the delays due to
pre- and post-processing of the signal.
The analysis of digital PLLs works the same as with analog ones, you
just exchange the Laplace transform with the Z-transform. You can add
arbitrary delays due to pre/post-processing as a simple multiplication
by 1/z for each clock cycle of delay.
I've found plenty of texts describing analog loop filters. Are there any
recommendations for digital loop filter PLL design?
The PLL book by Best contains two chapters on how to design digital PLLs.
I can also recommend "Understanding digital signal processing" by Lyons,
which is a very hands-on description how to do filters and perform other
signal processing tasks.
Attila Kinali
On Tue, 21 Mar 2017 11:19:22 -0400
paul swed paulswedb@gmail.com wrote:
Have to say a search for PLL book by Best generates lots of stuff. None of
it about PLLs. Better hint please? I think Lyons may be a bit better.
https://www.amazon.com/Phase-Locked-Loops-Simulation-Applications/dp/0071493751
I think that's the current edition...
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
Roland Best, "Phase Locked Loops". I see from Amazon that it is up the
6th edition. I think I have the 3rd edition.
I took a PLL class at StorageTek a while back; an earlier revision of
this book was used and I found it to be a good text.
DaveD
On 3/21/2017 9:19 AM, paul swed wrote:
Have to say a search for PLL book by Best generates lots of stuff. None of
it about PLLs. Better hint please? I think Lyons may be a bit better.
Regards
Paul
WB8TSL
On Tue, Mar 21, 2017 at 7:39 AM, Attila Kinali attila@kinali.ch wrote:
On Mon, 20 Mar 2017 21:32:28 -0700
James Peroulas james@peroulas.com wrote:
I'm trying to understand how to design and analyze the loop filters in a
digital PLL. Specifically, because of digital processing delays, the
phase
offset measured at time t will only produce a change on the VCXO input at
time t+T, where T is the sampling period of the digital loop.
You have the same delays in analog filters as well. As a rule of thumb
you can assume that the delays are in the same order of magnitude as
with the equivalent analog filters, not accounting for the delays due to
pre- and post-processing of the signal.
The analysis of digital PLLs works the same as with analog ones, you
just exchange the Laplace transform with the Z-transform. You can add
arbitrary delays due to pre/post-processing as a simple multiplication
by 1/z for each clock cycle of delay.
I've found plenty of texts describing analog loop filters. Are there any
recommendations for digital loop filter PLL design?
The PLL book by Best contains two chapters on how to design digital PLLs.
I can also recommend "Understanding digital signal processing" by Lyons,
which is a very hands-on description how to do filters and perform other
signal processing tasks.
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
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.
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