I am trying to count the output of a photodiode. It outputs 2V 20ns pulses. My counter is able to read anything above 3.3V and about 60ns.
I've built a comparator circuit able of amplifying the signal to 4V but the duration of the pulse is still too small.
Therefore I've tried adding an RC filter both to the input and the the output, separately.
For the first two images, the yellow is the input to the comparator and the purple is the output of the comparator. Here I tried to use the RC filter on the input to give the comparator more time to produce the wave, clearly didn't work. VRef is 0.5V.
For the last images this is what you recommended (although on FI4) with the resistor and cap going from FI4 input to ground. It's doing what it should but unfortunately the voltage is significantly lower.
Where do I go from here, is there any nice fix I can do or do I have to add a secondary amp or comparator?
If there is no filter the signal is just a delayed and amplified copy of the input. (with no negative part)
Edit:
Would something like this help (monostable)?
http://cache.national.com/ds/LM/LMC555.pdf
I've built a comparator circuit able of amplifying the signal to 4V but the duration of the pulse is still too small.
Therefore I've tried adding an RC filter both to the input and the the output, separately.
For the first two images, the yellow is the input to the comparator and the purple is the output of the comparator. Here I tried to use the RC filter on the input to give the comparator more time to produce the wave, clearly didn't work. VRef is 0.5V.
For the last images this is what you recommended (although on FI4) with the resistor and cap going from FI4 input to ground. It's doing what it should but unfortunately the voltage is significantly lower.
Where do I go from here, is there any nice fix I can do or do I have to add a secondary amp or comparator?
If there is no filter the signal is just a delayed and amplified copy of the input. (with no negative part)
Edit:
Would something like this help (monostable)?
http://cache.national.com/ds/LM/LMC555.pdf
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