If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
hboy007 wrote ...
the diode has 5 .. 6pF when biased with 15V and a rise/fall time of 50 .. 80ns, which sounds promising to me. Dark current is 4..20nA and current noise is 0.4 .. 1 pA / sqrt(Hz) - typical resp. maximum values. I'll be back with the calculations tomorrow. Thank you for your help!
Am looking forward to your lab results -- had never considered that position-senstive detectors could work so fast. Got some of these: Specified risetime is 1.5 us, but that's with 1k load instead of low impedance TIA.
As hboy knows, PSD's are unsurpassed for tracking a fast-moving light in one dimension. Spatial resolution equivalent to tens of thousands of pixels, and ( I see now ) "imaging rate" in the multi MHz. (to be honest, you don't get all of both parameters at once).
Registered Member #1792
Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527
The first two National application notes that come up here talk specifically about using current feedback opamps as photodiode amplifiers:
Hopefully it helps a bit.
edit: While finding information on an unrelated topic (Miller Theorem) I found this good set of notes on high-speed transistor level linear amplifier design. It's not specifically applied to what you're doing but it covers the techniques you would probably need to use if you wanted to do a transistor level design instead of an opamp.
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
I just found this paper about PSD array sensors:
it uses a different approach, placing an array of PSDs on a chip, just like this one here does it:
This definitively seems to be a hot topic in online 3d scanning, maybe we'll be able to see some applications of the type of scanner I had in mind when I started this thread.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
Thoughts which may or may not be in the above references (ok, I haven't looked at them)
I assume that at some point there will be an ADC (or many/multiplexed for a linear array) So I'd expect 'best' performance if the photo-diode-current is integrated (capacitor, dV=dQ/C) during the SAMPLE period and reset (discharged) after the HOLD period.
If a linear array is used then I guess the 'key' will be physical construction so groundplane, smd components and whatever dense packages of cmos switches (S&H), ADC, mux, amplifier, &c. (and a quick look at rf stripline design) are called for.
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
hboy007 wrote ...
the diode has 5 .. 6pF when biased with 15V and a rise/fall time of 50 .. 80ns, which sounds promising to me. Dark current is 4..20nA and current noise is 0.4 .. 1 pA / sqrt(Hz) - typical resp. maximum values. I'll be back with the calculations tomorrow. Thank you for your help!
Let's see the practical results:
and even more interesting, the C/V curve:
the capacitance at 0V is a bit random because there might be residual charges in the structure which dramatically change the actual zero voltage capacitance.
I felt like cooling the PSD down a little to make the leakage current look more promising. -20°C should be no problem with thermoelectric cooling. Coming up next: laser induced transient current measurements
5V bias voltage at -20°C would make for nice operating conditions, right?
ps. I bought 16 pc. of these PSDs to ensure the project will get anywhere soon.
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
EL5167 OPA2683
Do these look suitable to you? Maybe it is the best solution to start with a G=20 .. 100 transimpedance amplifier stage. OPA2683 is available in a dual package so the CFB opamps will be matched to some degree.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
large bandwidth amplifier (help needed)
