Re: Photodiode Dark Current Measurement
- From: redbelly <redbelly98@xxxxxxxxx>
- Date: Fri, 28 Sep 2007 23:08:11 -0000
On Sep 28, 7:09 am, GraemeC <graeme.cunning...@xxxxxxxxxxxxxx> wrote:
I am trying to measure the dark current of a photodiode
I have Chathode of the PD connected to 1Meg ohm resistor which is
connected to +2V
The annode is connected to 0V
I obtain the following measurements
Voltage accross Resistor: 1.39V
Voltage accross Photodiode : 0.82V
I have assumed that the Dark Current (or indeed any current value) is
(2 - (1.39+0.82)) / 1Meg
=> I obtain a dark current of 210nA. This figrue however is less by
more than an order of magnitude than that I am expecting.
Is my understaning wrong?
Please don't ask why I have this set up am not using Op-Amp circuity!
Many Thanks
Graeme
Your measured dark current, if we neglect the effect of the
voltmeter(s?) on your circuit, is 1.39 uA as John P. said. At least
that's closer to the >2 uA you were expecting (*). Perhaps your >2 uA
figure is a "max/worst case" value, or is the spec at a considerably
higher bias voltage than the 0.6 to 0.8V you had.
You might redo the measurement using a 100k resistor, and see if you
get close to the same current (i.e., 0.14V across the 100k resistor).
Also, I have some questions about your setup ...
1. What is the voltage of your "2V" supply, to the nearest 0.01V? The
diode and resistor voltages should add up to the supply voltage.
2. Did you measure the resistor and diode voltages at different times
with the same meter, or simultaneously with two separate meters?
Regards,
Mark
(*) GraemeC wrote:
=> I obtain a dark current of 210nA. This figrue however is less
by more than an order of magnitude than that I am expecting.
.
- References:
- Photodiode Dark Current Measurement
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- Photodiode Dark Current Measurement
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