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fast edges

  • Thread starter Gerhard Hoffmann
  • Start date
G

Gerhard Hoffmann

Jan 1, 1970
0
from usenet:

A these speeds you are mostly talking about integrated versus
discrete circuits. Do any of the most recent fpga's meet your needs?
They are in 28nm which is blazingly fast but I'm not sure if the i/o
would keep up

I'm after the fastest possible pulses to drive an electro-optic
modulator, with
a goal of making light pulses in the 10-100 ps range.

We are using the SERDES blocks of an Altera part to make fast LVDS
edges, but
the edges are quantized to the SERDES PLL clock, currently 1 GHz. The
fastest
stuff that I've seen coming out of an FPGA is around 60 ps rise/fall,
low level
LVDS. Delay temperature coefficients are terrible in FPGAs, so even if
you can
make fast edges, they drift all over the place.

This is interesting, if expensive.

http://www.hittite.com/content/documents/data_sheet/hmc841lc4b.pdf




auch interessant:
http://www.furaxa.com/PulserSamplerCore.htm



schönes Wochenende, Gerhard
 
G

Gerhard Hoffmann

Jan 1, 1970
0
Am 09.02.2013 21:51, schrieb John Larkin:Ooohps, this one went wrong...

was meant as a email pointer to a colleague until we meet on Monday :)
Thunderbird is !x%$'!!! aargh!

BTW I'll play this weekend with your ramp generator (the one with the
AD8009 bootstrap). I have a new Altium Designer installation and
choose it as an exercise.

Altium - Camtastic - pdf - offset film from nearby print shop -
empty board (self etched & drilled) in a long afternoon.

regards, Gerhard
 
G

Gerhard Hoffmann

Jan 1, 1970
0
Am 09.02.2013 21:51, schrieb John Larkin:
,
The clock-to-output prop delay is 10 ps typ. That's mind boggling. Light travels
across the width of the chip in more time than that.
And the rise/fall time to the decision point would be 6 ps of this.
That means, the "intent" to produce a different output level must travel
in 4 ps.

Looks weird. But interesting, nevertheless.

Gerhard
 
S

Spehro Pefhany

Jan 1, 1970
0
If you fudge the threshold definitions a little, you can claim negative prop
delay.

Resublimated thiotimoline semiconductors?


Best regards,
Spehro Pefhany
 
G

Gerhard Hoffmann

Jan 1, 1970
0
Am 10.02.2013 02:08, schrieb John Larkin:
Or some imperfectly matched cables.

or a missing 0 in the tpd spec.
8 risetimes through a master-slave FF seems ok.
 
G

Gerhard Hoffmann

Jan 1, 1970
0
Am 10.02.2013 01:34, schrieb John Larkin:
That seems to be a hazard of using the same program for mail and newsgroups.

Why is the button for "create new" (verfassen in my German version) on
the top left and "answer newsgroup", forward, Archive on the right side
under the list of articles... I want my Agent back. But I won't return
to Windows for it.
What's the application? Fast ramps are fun; fast ramps at 10-12 bit linearity
are even more fun.

This one is just to fathom how far I can go; I did something similar
with a switched current source in a time stretcher. We talked about that
last year.
It was for measuring the time of flight of just a few photons
(interpolation between clock edges)

<
http://www.google.de/url?sa=t&rct=j...=KO_mO3OuJETmIxdZAofhSQ&bvm=bv.42080656,d.Yms
page 33

The inductance of the ramp cap can be an issue if the discharge switch turns off
too fast. Sometimes I use a couple of caps in parallel, or slow down the turnoff
drive somehow. 1 ns speeds are interesting, but 100 ps is sort of a Chuck Yeager
style "wall in the sky."

This time I'd like to avoid the dual slope conversion and go
directly ramp to digital with a LTC2165. Avoids at least the
second switching, no droop in the slow part of the cycle,
no comparator bias current etc. And instead of a few hundred
stretch cycles per second I can get 20Meg at least.

At some point I got tired of ferric chloride stains on my person. I just
breadboard on copperclad, or order a board and do something else until it
arrives.

I use Ammoniumpersulfat and presensitized 0.5mm FR4 made by Bungard.
6 mil traces and gaps are easy with offset film.
Strictly single sided plus GND layer, stamp-sized and dense.

With the Altium snippet feature I can recycle the circuit diagram and
the layout as a macro for the real design.
I now have quite a lot of pre-characterized stamps that I can use to
click a board together (regulators, VCXOs, filters, frequency
multipliers, phase comparators...)

regards, Gerhard
 
N

Nico Coesel

Jan 1, 1970
0
Phil Hobbs said:
Which sort of suggests that there may be a bit of specsmanship at work.

Maybe they specced the unpackaged die.
 
J

Joerg

Jan 1, 1970
0
John said:
Why does everybody put the little buttons for reducing/deleting windows right
next to one another, when there's lots of room to spread them out? Why does the
Windows right-click list put Delete right next to Rename?

Hint: In Thinderbird you can customize the buttons. Just right-click the
tool bar where you aren't happy with stuff.

For example, I added a "Next" button because I find that rather useful
in newsgroups.

[...]
 
J

Jasen Betts

Jan 1, 1970
0
I run Agent in wine. Works pretty well without any fuss to install and
get it running. Help doesn't work properly though.

hve you installed "xchm" or is help broken in lyspice+wine too?
 
J

josephkk

Jan 1, 1970
0
hve you installed "xchm" or is help broken in lyspice+wine too?

I have tried installing xchm and both are still broken. It is very
possible i did something wrong though.

?-)
 
J

Jasen Betts

Jan 1, 1970
0
I have tried installing xchm and both are still broken. It is very
possible i did something wrong though.

?-)

from your descriptions it sounds kind of messed up.

you could try a fresh install by temporarily moving your ~/.wine
directory and reinstalling ltspice, if help and works in the new
install it's probablly something messed up in your wine install.

also test www with help -> about -> linear-tech-website
 
F

Fred Abse

Jan 1, 1970
0
I have tried installing xchm and both are still broken. It is very
possible i did something wrong though.


I used chm2pdf to convert the LTspice help into a nice indexed PDF.

Better, in fact than LT's own PDF offering.

Xchm doesn't always work with some later editions, beyond the first page.
 
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