Currently, I am using the photodiode in a transimpedance amplifier (TIA) operating in photovoltaic mode. However, I am observing a delayed response from the TIA.
I also tried applying a +9 V reverse-bias voltage to operate the photodiode in photoconductive mode, but the TIA did not respond to the LED signal, which has a frequency of 360 Hz and a 1% duty cycle.
As I am not an expert in photodetection circuits, I would appreciate your guidance and suggestions on how to configure and use the photodiode in photoconductive mode.
Hi Hasham
As in the previous thread on the same subject you are providing minimum information. The latest schematic (circuit diagram) would be a big help)
Is the current circuit working OK except for that delay???
What makes you think that changing the diode operating mode is going to cure this delay.
How long is the delay.
All circuits have SOME delay. It is because of a funny trait in physics. It is impossible for anything or any state to be in 2 different places at the same time. That is it is impossible for a node in an electronic device to be high and low or anything else for that matter at the same time. So there must be some delay which in the case of a device with lots of processing will vary depending on the device.
I once worked on a synthesiser which as part of a VCO control it had 2 ICs in a “Pulse Swallower” circuit. To operate correctly the “Propagation Delay” had to be as close as possible to the same so these 2 ICs (the same type) had to be selected as a pair. Indeed if it was required to replace either one they had to be changed in selected pairs.
So I think that it is quite possible that the actual amplifier is the reason for the delay and not the diode operation mode.
Cheers Bob
Hi Hasham
This sort of thing might interest you. It seems to be a complete transimpedance amplifier with a photodiode and amplifier all in the one package.
TI product
Cheers Bob
