sine to square wave circuits - performance data?
Wenzel says an HC device tends to work better than an AC device in squarer applications.
My calibrator board has a place for the feedback resistor so that I can implement the second LPRO circuit (or add hysteresis to the squarer gate.
I find it interesting that a simple 74AC04 performs so well (given enough
input power) compared to even an LT1016.
Hi
On Oct 4, 2017, at 11:21 AM, Mark Sims holrum@hotmail.com wrote:
Wenzel says an HC device tends to work better than an AC device in squarer applications.
That’s not the case for broadband phase noise or for close in jitter. The issue with the older
AC parts is the crummy lead frame pinout. Setting them up so they did not oscillate was not
as easy as it should have been. More modern single gate packages no long have those issues.
There is always an … except … If you do a “feedback resistor” bias, forget about any sort of
fast gate. Bias it with two resistors on the input and it should be fine. If the second resistor blows
your budget then yes, it’s a issue.
Bob
My calibrator board has a place for the feedback resistor so that I can implement the second LPRO circuit (or add hysteresis to the squarer gate.
I find it interesting that a simple 74AC04 performs so well (given enough
input power) compared to even an LT1016.
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Just avoid current flowing in the input protection circuitry.
Once the protection circuit is activated the jitter increases significantly.
Bruce
On 05 October 2017 at 04:21 Mark Sims <holrum@hotmail.com> wrote:
Wenzel says an HC device tends to work better than an AC device in squarer applications.
My calibrator board has a place for the feedback resistor so that I can implement the second LPRO circuit (or add hysteresis to the squarer gate.
----------------
I find it interesting that a simple 74AC04 performs so well (given enough
input power) compared to even an LT1016.
_______________________________________________
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On Wed, 4 Oct 2017 15:21:45 +0000
Mark Sims holrum@hotmail.com wrote:
My calibrator board has a place for the feedback resistor so that I can
implement the second LPRO circuit (or add hysteresis to the squarer gate.
I am not sure whether you meant that the feedback resistor adds hysteresis
to the squarer gate, but it does the exact opposite: it reduces hysteresis.
And that's exactly the point: less hysteresis means less jitter.
And as a nice side effect, it acts as a control loop to keep the output
duty cycle close to 50%.
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
On Wed, 4 Oct 2017 16:51:23 -0400
Bob kb8tq kb8tq@n1k.org wrote:
There is always an … except … If you do a “feedback resistor” bias,
forget about any sort of fast gate. Bias it with two resistors on the
input and it should be fine. If the second resistor blows your budget
then yes, it’s a issue.
A relatively easy way around this is to replace the feedback resistor
by an R-C-R filter with a low enough corner frequency.
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
On Thu, 5 Oct 2017 10:11:37 +1300 (NZDT)
Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Just avoid current flowing in the input protection circuitry.
Once the protection circuit is activated the jitter increases significantly.
Do you know what the mechanism is, that increases jitter in this case?
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
Substrate currents biasing on parasitic devices in junction isolated process?
If so, then silicon on insulator CMOS may not exhibit the effect.
Bruce
On 05 October 2017 at 10:18 Attila Kinali attila@kinali.ch wrote:
On Thu, 5 Oct 2017 10:11:37 +1300 (NZDT)
Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Just avoid current flowing in the input protection circuitry.
Once the protection circuit is activated the jitter increases significantly.
Do you know what the mechanism is, that increases jitter in this case?
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
Hi
The other issue could be that no diode ever operates instantaneously ….
Bottom line is indeed that clipping in protection diodes is not a good idea. External
diodes …. who knows ….
Bob
On Oct 4, 2017, at 5:33 PM, Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Substrate currents biasing on parasitic devices in junction isolated process?
If so, then silicon on insulator CMOS may not exhibit the effect.
Bruce
On 05 October 2017 at 10:18 Attila Kinali attila@kinali.ch wrote:
On Thu, 5 Oct 2017 10:11:37 +1300 (NZDT)
Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Just avoid current flowing in the input protection circuitry.
Once the protection circuit is activated the jitter increases significantly.
Do you know what the mechanism is, that increases jitter in this case?
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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Am 05.10.2017 um 00:33 schrieb Bob kb8tq:
Hi
The other issue could be that no diode ever operates instantaneously ….
Bottom line is indeed that clipping in protection diodes is not a good idea. External
diodes …. who knows ….
And when it clips, it provides a low impedance connection
between the input and the power supply. Nobody knows
the recovery time.
Gerhard
Thomas Knox
Sr Test and Measurement Engineer
Ascent Concepts and Technology
4475 Whitney Place
Boulder Colorado 80305
1-303-554-0307
actast@hotmail.com
From: time-nuts time-nuts-bounces@febo.com on behalf of Mark Sims holrum@hotmail.com
Sent: Wednesday, October 4, 2017 9:21 AM
To: time-nuts@febo.com
Subject: [time-nuts] sine to square wave circuits - performance data?
Wenzel says an HC device tends to work better than an AC device in squarer applications.
My calibrator board has a place for the feedback resistor so that I can implement the second LPRO circuit (or add hysteresis to the squarer gate.
I find it interesting that a simple 74AC04 performs so well (given enough
input power) compared to even an LT1016.
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.