Hi,
I'm currently working on a poject involving modulation of a current through an LED. I'm not really
I need to send a variable luminous waveform to a Device Under Test, but the light should only be emitted when the DUT itself is sending light.
I plan to use a photodiode coupled to a LMV7219 comparator to detect when to send the light.
The DUT output light pulse length is around 50µs. The system must send the light at maximum 5µs after the DUT light pulse starts .
There is a small SAMD11 MCU handling the waveform generation. I'm using a filtered PWM signal as a DAC, that feeds a constant current surce amplifier.
To modulate this waveform, I have thought about 2 options :
A. chop the input of the current source by connecting the input to ground
B. chop the output of the current source by disconnecting the current source from ground.
I created a quick simulation using Falstad to illustrate my ideas (interactive link :
http://tinyurl.com/24ngzoer) :
Are these 2 options viable ? What would be the best one option ?
My analog electronic skills are quite limited, so thanks in advance for your help.
Théo