They are relevant when a high input impedance buffer is used making it
easier to add series/shunt overload protection. Protecting against
400 volts and higher is feasible this way.
Adding overload protection to a 50 ohm input is an interesting
challenge but it can be done. Precede the 50 ohm ter
David wrote:
If the 10pA specification is guaranteed by design, then wouldn't they
have to be testing the 1pA "A" parts?
That assumes the parts are produced by exactly the same process, which
is very often not a safe assumption. One of them may undergo extra
process steps, for example, or o
Hi
If you go back in the thread, it started out as a “general purpose front end”
design. One of the
suggested parameters on that design was a high impedance input capability in
the 1mega ohm range.
Noise on a hi-z input is always an issue and input protection just makes it
worse.
About the
David wrote:
I ended up qualifying 2N3904s based on manufacturer and lot and I
think we ended up using ones from Motorola. I wish detailed process
information like National had was available from every manufacturer.
It is, if you ask the process engineers for it. (From the Big Boys,
that is
David wrote:
I ended up qualifying 2N3904s based on manufacturer and lot and I
think we ended up using ones from Motorola. I wish detailed process
information like National had was available from every manufacturer.
It is, if you ask the process engineers for it. (From the Big Boys,
that is
I have a really naive question: how can picoamp leakage parts be relevant in
low impedance input pulse conditioning to an interval counter?
Tim N3QE
> On Apr 11, 2017, at 7:46 AM, Bob kb8tq wrote:
>
> Hi
>
>
>> On Apr 11, 2017, at 7:05 AM, Charles Steinmetz wrote:
>>
>> David wrote:
>>
>>
Hi
Testing can mean a lot of different things. Did they test every single part
they shipped for every parameter?
Did they just do a sample of parts and decide the lot was good? Did they test a
sample of parts for a sub-set
of the specs and decide they were good? Did they test them after packagin
Hi
> On Apr 11, 2017, at 7:05 AM, Charles Steinmetz wrote:
>
> David wrote:
>
>> I ended up qualifying 2N3904s based on manufacturer and lot and I
>> think we ended up using ones from Motorola. I wish detailed process
>> information like National had was available from every manufacturer.
>
L
9000 in "2001: A Space Odyssey."
Bill Hawkins
-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
kb8tq
Sent: Sunday, April 09, 2017 1:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] TAPR TICC boxed (
ngerprint
>> made a huge difference. The carbon filled black paint was practically a
>> short.
>> Maybe an overcoat with silicone or some other type of low leakage sealant,
>> then the black paint?
>>
>> Tom
>>
>>> From: David
>>> T
On Sat, 8 Apr 2017 16:30:38 -0400, you wrote:
>David wrote:
>
>> I mentioned this in connection with some manufacturers using gold
>> doping in transistors which would not normally be expected to have
>> gold doping. So you end up with a bunch of lessor named 2N3904s which
>> meet the 2N3904 spec
On Sat, 8 Apr 2017 21:43:31 +0200, you wrote:
>Am 08.04.2017 um 17:52 schrieb David:
>>
>> If they are not being tested, then where is the maximum specified
>> leakage number coming from? For a small signal bipolar transistor it
>> will typically be 25nA, 50nA, or 100nA, but the InterFET datashee
aint?
>
>Tom
>
>> From: David
>> To: Discussion of precise time and frequency measurement
>>
>> Sent: Saturday, April 8, 2017 10:00 AM
>> Subject: Re: [time-nuts] TAPR TICC boxed (input protection)
>>
>>On Fri, 7 Apr 2017 01:06:17 -0400, y
David wrote:
I mentioned this in connection with some manufacturers using gold
doping in transistors which would not normally be expected to have
gold doping. So you end up with a bunch of lessor named 2N3904s which
meet the 2N3904 specifications but are useless if you were looking for
low leak
David wrote:
So gold doping does work with PNP devices. Previously when I brought
it up, I was told gold doping only applied to NPN devices leading to
my confusion.
Since I posted, I dug through my books and found a few more references
on point:
A couple of textbooks say commercial PNP fas
Am 08.04.2017 um 17:52 schrieb David:
If they are not being tested, then where is the maximum specified
leakage number coming from? For a small signal bipolar transistor it
will typically be 25nA, 50nA, or 100nA, but the InterFET datasheet (1)
shows 10pA maximum and 1pA maximum for the A versio
The Siliconix PAD1 at 1pA and 0.8pF is still available :
http://www.micross.com/pdf/LSM_PAD1_TO-72.pdf
On Sat, Apr 8, 2017 at 4:52 PM, David wrote:
> On Thu, 6 Apr 2017 22:23:43 -0400, you wrote:
>
> >David wrote:
> >
> >> I know one thing to watch out for if you are looking for low
> >> leaka
and frequency measurement
Sent: Saturday, April 8, 2017 10:00 AM
Subject: Re: [time-nuts] TAPR TICC boxed (input protection)
On Fri, 7 Apr 2017 01:06:17 -0400, you wrote:
controlling the offset voltage.
We ended up painting the diodes black after soldering.
I have also heard of it
On Thu, 6 Apr 2017 22:23:43 -0400, you wrote:
>David wrote:
>
>> I know one thing to watch out for if you are looking for low
>> leakage is gold doping
>
>Anything that increases carrier mobility increases leakage current (all
>else equal -- i.e., for each particular device geometry). This acco
On Fri, 7 Apr 2017 01:06:17 -0400, you wrote:
>Another thing to watch out for if you need very low leakage, is if the
>package is transparent. All junctions are photodiodes.
>
>Maybe it's less of a problem now with SMTs, than it was with glass body
>diodes or translucent transistor packages.
>
>A
On Fri, 7 Apr 2017 04:09:38 -0400, you wrote:
>David wrote:
>
>>> what doping is used for PNP RF transistors and saturated switches
>>> if it is not gold? Does it also increase leakage?
>
>I replied:
>
>> Gold doping doesn't affect the speed of BJTs in the active region very
>> much -- its purpos
David wrote:
what doping is used for PNP RF transistors and saturated switches
if it is not gold? Does it also increase leakage?
I replied:
Gold doping doesn't affect the speed of BJTs in the active region very
much -- its purpose is to reduce minority carrier lifetime and, thereby,
to redu
Another thing to watch out for if you need very low leakage, is if the
package is transparent. All junctions are photodiodes.
Maybe it's less of a problem now with SMTs, than it was with glass body
diodes or translucent transistor packages.
Andy
___
ti
David wrote:
I know one thing to watch out for if you are looking for low
leakage is gold doping
Anything that increases carrier mobility increases leakage current (all
else equal -- i.e., for each particular device geometry). This accounts
for the much higher leakage of Schottky and germa
On Wed, 5 Apr 2017 02:40:13 -0400, you wrote:
>David wrote:
>
>> So collector-base junctions make good low leakage high voltage diodes
>> although they are slow
>
>I guess it depends on what one means by "slow" and "fast."
I was referring to within the same transistor; emitter-base junctions
are
David wrote:
So collector-base junctions make good low leakage high voltage diodes
although they are slow
I guess it depends on what one means by "slow" and "fast."
The B-C junction of an MPSH10/MMBTH10 or 2N/PN/MMBT5179 switches on in
<1nS and off in <2nS, which is comparable with Schottky
The gold standard is a random pulse source.
Using something like a SPAD as the source of random pulses is popular as the
average rate can be easily adjusted by changing the light level. It also avoids
using radioactive sources.
Bruce
> On 03 April 2017 at 15:05 Bruce Griffiths wrote:
>
>
> Fo
On Wed, 5 Apr 2017 09:13:34 +1200 (NZST), you wrote:
>A protection diode needs to also have a fast turn on with little or no
>overshoot of the forward voltage.
That would be ideal but forward turn on time is rarely specified and
usually assumed to be fast and some fast diodes have appallingly sl
A protection diode needs to also have a fast turn on with little or no
overshoot of the forward voltage.
Reverse recovery time can be an issue if one is relying on the clamp for
protection against a periodic overload such as when an input is overdriven by a
sinewave input and one wishes to mak
Low current measurements take a lot of time on the automatic test
equipment and time in this case is measured in seconds. The same
applies to low frequency noise.
For an example, take a look at the National (now TI) LMC6001 and
LMC6081:
https://goo.gl/LCY2vR
Unlike National, TI does not care ab
http://www.spacetechexpo.eu/assets/files/2015/Recent-Developments-in-Phase-Stable-Cables.pdf
is a more readily accessible source of data on coax cable delay tempco et.
Bruce
>
> On 04 April 2017 at 00:13 Bruce Griffiths
> wrote:
>
> Copper jacketed low density PTFE insulated coax cab
2017 3:05 AM
To: Mark Sims; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] TAPR TICC boxed
For even more fun you could try to detect the PTFE phase change at around 20C
using a cable with PTFE dielectric.
A pulse source with somewhat more pulse to pulse jitter m
Copper jacketed low density PTFE insulated coax cables typically exhibit a net
phase change of over 1000ppm during the PTFE phase transition. See figure 2 p14
of the Cables and connectors supplement to March 2017 microwave journal. Solid
PTFE insulated cables exhibit an even greater (2 -3x) phas
Hi
You could simply immerse all the cables in a swimming pool full of mercury … :)
(bonus points for a link to the prior discussion of that topic ..).
Bob
> On Apr 2, 2017, at 11:05 PM, Bruce Griffiths
> wrote:
>
> For even more fun you could try to detect the PTFE phase change at around
>
On Mon, 3 Apr 2017 15:05:55 +1200 (NZST)
Bruce Griffiths wrote:
> For even more fun you could try to detect the PTFE phase change at around
> 20C using a cable with PTFE dielectric.
This will require several 100 meters of cable to be measureable with
the TICC. Modern cables are all <500ppm/K,
For even more fun you could try to detect the PTFE phase change at around 20C
using a cable with PTFE dielectric.
A pulse source with somewhat more pulse to pulse jitter may be more useful in
that averaging will occur over a wider range of fine interpolator codes.
Bruce
>
> On 03 April 2
The autotune cable delay nulling feature works by putting the TICC into debug
mode which outputs time stamps (and other info) of both channels. Since each
channel is being fed by the same signal, the stamps of each channel should be
the same. Heather calculates the average chA-chB difference
I implemented the channel offset compensation feature specifically to make
measuring cable delays more accurate. I wanted to measure my TDR calibration
cable and another very precision delay line. I used Heather to null out the
channel/connector delays and then replaced one of the "T" cables w
The FJH1100 is specified for reverse leakage of 10pA at 15v (which is
also the absolute maximum working voltage), and 3pA reverse leakage at
5v. Junction capacitance is 2pF. They cost $8.90 each at Mouser.
The B-C junction of an MPSH10 or MMBTH10 (SMT version) has only half as
much reverse l
Hi
One interesting “feature” of leakage specs:
They often reflect the measurement limit rather than the actual device
performance. If they
are guaranteed by test, the limit may be orders of magnitude above the actual
performance.
That’s on top of the likely “rated at max temperature” part th
Hi
If need it, indeed coming up with individual delays is a bit of a pain. One of
the most basic decisions is to establish a reference plane. More or less - the
signal at “this point” is zero. Everything else is going to be off by
nanoseconds from that point (with meter long cables involved). I
Its usually not possible to uniquely assign individual channel delays in this
way, however swapping cables allows the cable delay mismatch to be eliminated
from the measurement of the differential delay between channels.
Eliminating the effect of cable delay mismatch can be useful when adjusting
The new TICC support in Lady Heather has an "autotune" function that can null
out the cable and channel delays. You connect a signal (like 1PPS) to both
channels through matched cables (like via a T adapter) and it averages the
difference and sets the "FUDGE" factor for one of the channels to n
Hi
The whole delay difference thing does get into a “do you care?” sort of
category. The
testing process you are doing may well calibrate out (or ignore) an offset of
this nature.
This is quite true in a number of TimeNut sort of tests.
Bob
> On Apr 1, 2017, at 4:02 AM, Bruce Griffiths
>
Hi
There are low(fish) leakage / low capacitance / high speed transient suppressor
diodes out there.
The aren’t going to do anything good in a 1 megohm environment. They are quite
useful in lower impedance circuits.
Bob
> On Apr 1, 2017, at 1:49 AM, Scott Stobbe wrote:
>
> Also interesting
The common mode propagation delay dispersion is also likely to be significant
unless one uses an SiGe ECL/CML comparator.
Calibrating this or actually the differential dispersion between channels is an
interesting but not insoluble issue.
Bruce
>
> On 01 April 2017 at 18:49 Scott Stobbe
Also interesting the LTC6752 is rail-rail input. Any rail-rail input opamp
I've used ends up with an ugly bump in input offset voltage transitioning
from the nmos or npn diff pair to the pmos or nmos. I'm not sure how good
or bad a rail-rail comparator may behave when common-mode biased in that
reg
Attempting sub nanosecond timing with an actual 1Mohm source is an exercise in
futility. There are very few cases where one would want to attempt precision
timing measurements with such a high impedance source. The 1M pulldown on the
TICC input is merely intended to maintain a valid logic input
Also for interest the 53131a schematic is available at
http://bee.mif.pg.gda.pl/ciasteczkowypotwor/HP/53131.pdf
HP used a low input bias current bjt opamp, the Lt1008 to bias/dc servo a
custom JFET buffer driving an AD96687 comparator.
On Fri, Mar 31, 2017 at 10:34 PM Scott Stobbe
wrote:
> Fwiw
Mark wrote:
I thought about using the clamp diodes as protection but was a bit worried
about power supply noise leaking through the diodes and adding some jitter to
the input signals...
It is a definite worry even with a low-noise, 50 ohm input, and a
potential disaster with a 1Mohm input.
Fwiw, for a precision comparator you'll probably want a bipolar front end
for a lower flicker corner and better offset stability over cmos. For
high-speeds the diffpair is going to be biased fairly rich for bandwidth.
So you will more than likey have input bias currents of 100's of nA to uA
on your
FJH1100
Ultra Low Leakage Diode
Alex
On 3/31/2017 6:00 PM, Charles Steinmetz wrote:
Mark wrote:
I thought about using the clamp diodes as protection but was a bit
worried about power supply noise leaking through the diodes and
adding some jitter to the input signals...
It is a definite wo
I thought about using the clamp diodes as protection but was a bit worried
about power supply noise leaking through the diodes and adding some jitter to
the input signals... I'm probably just being paranoid. The TICC doesn't have
the resolution for it to matter or justify a HP5370 or better qu
(this might be a duplicate post... the last time I sent this, the message
bounced)
What did you do for input protection?
I want to build an input system for the TICC that incorporates some input
protection, switchable terminator, possibly settable threshold and edge
selects, and a switchabl
.@febo.com
A "time-nuts@febo.com" time-nuts@febo.com
Cc
Data Thu, 30 Mar 2017 20:15:09 +0000
Oggetto [time-nuts] TAPR TICC boxed
What did you do for input protection?
I want to build an input system for the TICC that incorporates some input
protection, switchable terminato
A single or dual supply CMOS output comparator should suffice together with
some diode clamps.
Since the TICC only resolves a few tens of picosec the choice of comparator etc
isnt critical.
LTC6752 (~$US2) or similar perhaps?
A single supply comparator should suffice unless you want to measur
What did you do for input protection?
I want to build an input system for the TICC that incorporates some input
protection, switchable terminator, possibly settable threshold and edge
selects, and a switchable PICDIV divider like the TADD-2 Mini. That would
allow inputs of <1 .. 100 (or mayb
57 matches
Mail list logo
