Clock Driver Design
I am working on a small clock distributor and wanted to get some ideas
on what works best for 10MHz and 1PPS driver circuits. I remember
sifting through the archives a year or so ago and tripped on some
discussion of this but I can't find it anymore.
Tom
Hi
Standard high speed CMOS logic works pretty well. How crazy are you trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some ideas on what works best for 10MHz and 1PPS driver circuits. I remember sifting through the archives a year or so ago and tripped on some discussion of this but I can't find it anymore.
Tom
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.
I am looking into various degrees of craziness. The source is CMOS and
there are plenty of 1 in to N out parts designed to drive clocks on a
PCB but not much is said about driving clocks on to a random length of
coax to another piece of equipment and what additional precautions that
might warrant. I am also considering making a sine wave output and
maybe other frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some ideas on what works best for 10MHz and 1PPS driver circuits. I remember sifting through the archives a year or so ago and tripped on some discussion of this but I can't find it anymore.
Tom
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.
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.
For low phase noise output at lower frequencies you should consider a
lambda divider feeding a low pass filter.
Although wideband opamps are convenient a discrete buffer amp can
produce a higher level output with lower additive phase noisee.
Bruce
Tom Minnis wrote:
I am looking into various degrees of craziness. The source is CMOS
and there are plenty of 1 in to N out parts designed to drive clocks
on a PCB but not much is said about driving clocks on to a random
length of coax to another piece of equipment and what additional
precautions that might warrant. I am also considering making a sine
wave output and maybe other frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you
trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some
ideas on what works best for 10MHz and 1PPS driver circuits. I
remember sifting through the archives a year or so ago and tripped
on some discussion of this but I can't find it anymore.
Tom
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.
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.
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.
Would an analog video distribution amplifier work?
These are available cheap.
TV stations used these eight or so in a frame.
The frame had a power supply and the BNC i/o connectors.
Each da would drive 6 or 8 outputs.
73
Glenn
WB4UIV
Retired TV CE.
At 01:28 PM 9/26/2013, you wrote:
I am looking into various degrees of craziness. The source is CMOS
and there are plenty of 1 in to N out parts designed to drive clocks
on a PCB but not much is said about driving clocks on to a random
length of coax to another piece of equipment and what additional
precautions that might warrant. I am also considering making a sine
wave output and maybe other frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you
trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some
ideas on what works best for 10MHz and 1PPS driver circuits. I
remember sifting through the archives a year or so ago and tripped
on some discussion of this but I can't find it anymore.
Tom
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.
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.
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.
TV video distribution amps work very nicely. Even better if you open them
up and change the matching from 75ohm to 50. :)
Bob
On Thu, Sep 26, 2013 at 3:19 PM, Glenn Little WB4UIV <
glennmaillist@bellsouth.net> wrote:
Would an analog video distribution amplifier work?
These are available cheap.
TV stations used these eight or so in a frame.
The frame had a power supply and the BNC i/o connectors.
Each da would drive 6 or 8 outputs.
73
Glenn
WB4UIV
Retired TV CE.
At 01:28 PM 9/26/2013, you wrote:
I am looking into various degrees of craziness. The source is CMOS and
there are plenty of 1 in to N out parts designed to drive clocks on a PCB
but not much is said about driving clocks on to a random length of coax to
another piece of equipment and what additional precautions that might
warrant. I am also considering making a sine wave output and maybe other
frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you
trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some ideas
on what works best for 10MHz and 1PPS driver circuits. I remember sifting
through the archives a year or so ago and tripped on some discussion of
this but I can't find it anymore.
Tom
_____________**
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/**
mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_____________**
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/**
mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_____________**
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/**
mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_____________**
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/**
mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Tom,
If you are building your own board - I have used this part:
SN74LVC1G125 - Single Bus Buffer Gate with 3-State Output
and it is suitable for the job. I have measured the performance of the
logic family - and what I observed follows what is in the spec sheets from
TI. I did not officially record
my measurements as I didn't do the testing on precision, calibrated
equipment. But I did do all testing at 10MHz and I did also look at the
1PPS signal of course.
I have used other parts in this logic family from TI and have had good
results at these frequencies.
73's,
John
AJ6BC
On Thu, Sep 26, 2013 at 1:22 PM, Bob Bownes bownes@gmail.com wrote:
TV video distribution amps work very nicely. Even better if you open them
up and change the matching from 75ohm to 50. :)
Bob
On Thu, Sep 26, 2013 at 3:19 PM, Glenn Little WB4UIV <
glennmaillist@bellsouth.net> wrote:
Would an analog video distribution amplifier work?
These are available cheap.
TV stations used these eight or so in a frame.
The frame had a power supply and the BNC i/o connectors.
Each da would drive 6 or 8 outputs.
73
Glenn
WB4UIV
Retired TV CE.
At 01:28 PM 9/26/2013, you wrote:
I am looking into various degrees of craziness. The source is CMOS and
there are plenty of 1 in to N out parts designed to drive clocks on a
PCB
but not much is said about driving clocks on to a random length of coax
to
another piece of equipment and what additional precautions that might
warrant. I am also considering making a sine wave output and maybe
other
frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you
trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some ideas
on what works best for 10MHz and 1PPS driver circuits. I remember
sifting
through the archives a year or so ago and tripped on some discussion
of
this but I can't find it anymore.
Tom
_____________**
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.
_____________**
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.
_____________**
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.
_____________**
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.
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.
Hi
How clean is your clock source? If you have something that is -150 dbc at 1 Hz, then you probably need some fancy analog gizmos. If you can make do with "only" -110 to -120 dbc/Hz at 1 Hz, then properly driven LVC CMOS will do just fine. That's true for a square or a sine output. Since you pretty much can't find an OCXO better than -120 at 1 Hz, I'd bet you'll be ok. 5 volt logic will be a little more quiet than 3.3V. More or less faster is quieter as long as you stay with saturated silicon CMOS. Change materials and all bets are off.
For square wave cable drive you can parallel up a couple of the '125 or '126 gates to get how ever much power you want to put into the cable. You can source or load terminate (or both). If you source and load terminate, your logic levels will be 1/2 the output. With either source only or load only termination you can get full swing logic levels. More drive will always be required with load termination (you are putting current into 50 ohms).
Logic IC's are cheap, easy to use, and simple to find. A low voltage single supply drives them and they aren't current hogs unless heavily loaded. What's not to like?
Bob
On Sep 26, 2013, at 1:28 PM, Tom Minnis Tom_minnis@att.net wrote:
I am looking into various degrees of craziness. The source is CMOS and there are plenty of 1 in to N out parts designed to drive clocks on a PCB but not much is said about driving clocks on to a random length of coax to another piece of equipment and what additional precautions that might warrant. I am also considering making a sine wave output and maybe other frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some ideas on what works best for 10MHz and 1PPS driver circuits. I remember sifting through the archives a year or so ago and tripped on some discussion of this but I can't find it anymore.
Tom
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.
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.
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.
Bob,
Totally agree.
24mA of drive at 3.3V is pretty nice in a small footprint for the parts we
are discussing. Of course as you have pointed out you can drive them at 5V
too.
Mini-circuits is a good place to look too - especially for us hobbyists:
http://www.minicircuits.com/products/DesignerKits.shtml
73's,
John
AJ6BC
On Thu, Sep 26, 2013 at 3:05 PM, Bob Camp lists@rtty.us wrote:
Hi
How clean is your clock source? If you have something that is -150 dbc at
1 Hz, then you probably need some fancy analog gizmos. If you can make do
with "only" -110 to -120 dbc/Hz at 1 Hz, then properly driven LVC CMOS will
do just fine. That's true for a square or a sine output. Since you pretty
much can't find an OCXO better than -120 at 1 Hz, I'd bet you'll be ok. 5
volt logic will be a little more quiet than 3.3V. More or less faster is
quieter as long as you stay with saturated silicon CMOS. Change materials
and all bets are off.
For square wave cable drive you can parallel up a couple of the '125 or
'126 gates to get how ever much power you want to put into the cable. You
can source or load terminate (or both). If you source and load terminate,
your logic levels will be 1/2 the output. With either source only or load
only termination you can get full swing logic levels. More drive will
always be required with load termination (you are putting current into 50
ohms).
Logic IC's are cheap, easy to use, and simple to find. A low voltage
single supply drives them and they aren't current hogs unless heavily
loaded. What's not to like?
Bob
On Sep 26, 2013, at 1:28 PM, Tom Minnis Tom_minnis@att.net wrote:
I am looking into various degrees of craziness. The source is CMOS and
there are plenty of 1 in to N out parts designed to drive clocks on a PCB
but not much is said about driving clocks on to a random length of coax to
another piece of equipment and what additional precautions that might
warrant. I am also considering making a sine wave output and maybe other
frequencies.
Tom
On 9/26/2013 4:34 AM, Bob Camp wrote:
Hi
Standard high speed CMOS logic works pretty well. How crazy are you
trying to get?
Bob
On Sep 26, 2013, at 1:48 AM, Tom Minnis Tom_minnis@att.net wrote:
I am working on a small clock distributor and wanted to get some ideas
on what works best for 10MHz and 1PPS driver circuits. I remember sifting
through the archives a year or so ago and tripped on some discussion of
this but I can't find it anymore.
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
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.
Hi
Ok, the SN74LVC1G125 is 35 cents each at Mouser if you buy at least 10 pieces. That's going to be $3.50. LM78L05 is 26.5 cents if you buy 10 pcs. You will need some bypass caps and resistors, I'd assume you already have them.
Say you want 10 channels, that's 11 logic id's. At one IC per output that's almost $4 plus the 27 cent regulator. Still under $5 for all the parts. It's roughly $10 if you double up on all the output channels.
Do a quickie PCB from any of the usual outfits for $10 or so on a small run / one day turn basis.
Total cost without connectors or case < $20 in very small quantities.
Bob
On Sep 26, 2013, at 5:05 PM, "John C. Westmoreland, P.E." john@westmorelandengineering.com wrote:
SN74LVC1G125