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Reply-To: "fred bartoli"
From: "fred bartoli"
References: <3DACB831.F814C3D6@webaccess.net> <3DAD0481.A4004E95@NOSPAM.univ-lille1.fr> <3DAD0A0A.1F7BF2DD@webaccess.net> <firstname.lastname@example.org> <3DAD665D.41787E1A@webaccess.net>
Subject: Re: Photodiodes in photovoltaic mode, speed considerations.
Date: Wed, 16 Oct 2002 15:34:04 +0200
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Chuck Simmons a écrit dans le message :
fred bartoli wrote:
> Chuck Simmons a écrit dans le message :
> > "s.d." wrote:
> > >
> > --
>> What is your laser power (current) ?
>> If it's low enough, you could simply sightly offset the laser &
>> pair form the ground by inserting one diode (or two) in the lower branch.
>> Then you'll have 0.7V (1.4V) room for a transimpedance amplifier with say
>> about 0.5V (1.2V) full scale output.
>I thought about it but the manufacturers of the optical units connect
>the laser cathode to power ground. I don't control the circuits on the
>optical units. I live with them. This means that I definitely have a
>photovoltaic diode referenced to system ground. The question is
>predicting the speed of the diode given inadequate data and not one of
>redesigning some other company's circuits. I want to select a clock
>frequency for the power controller for each type of laser rather than
>design additional circuits.
Do you really want to calculate this ?
Is your pb a case by case pb on production runs, a lot by lot, or doing this
once for each device ref ?
You could simply measure the photodiode response to a light step.
Drive the laser to a safe level, or if you can't drive the photodiode with
an external light source.
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