hi p,
In post #36, Rsh is shown as 1E9, in your posted asc file it is now 2E9.
Is there a reason for that change.?
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View attachment 232785View attachment 232786

Hi, no, I was testing here and I made a mistake. Thank you for your complete accuracy.

 

hi pooya,
This is one example showing how to reduce the falling edge of the amplified pulse.
Control the Vbias On/Off time and polarity, you will need a fast OPA to create the pulse.
Modify it to suit your project.
Image shows the original version and the modified Vbias for comparison.

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View attachment 232805

Thank you very much

 

hi pooya,
This is one example showing how to reduce the falling edge of the amplified pulse.
Control the Vbias On/Off time and polarity, you will need a fast OPA to create the pulse.
Modify it to suit your project.
Image shows the original version and the modified Vbias for comparison.

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View attachment 232805

hi
Do you think this circuit is suitable for my work?
I saw the circuit you sent, I think you misunderstood what I meant. I do not want to just have a whole square wave. The way you said it was great.
I have more to have accurate waveforms. That means I need to have exactly the right waveform.

 

Do you think this circuit is suitable for my work?

hi p,
It is not possible for me to say if that is suitable, I do not know the exact specification of the pulse you require.?
I would need more details of the project design specification.

I understood from your earlier posts you just required a fast Off time for the pulse.
What was the purpose of posting that circuit from Analog Devices.?
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hi p,
It is not possible for me to say if that is suitable, I do not know the exact specification of the pulse you require.?
I would need more details of the project design specification.

I understood from your earlier posts you just required a fast Off time for the pulse.
What was the purpose of posting that circuit from Analog Devices.?
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It is better to say that I do not need a quick shutdown.
In that example, it was clear that the photodide did not have the correct shutdown time and would turn off very slowly.
I want the photodiode to give me a real time pulse and event.
Most of my work is on measuring life time phosphorescence. If the photodiode has a lot of fall time, I can not do exactly this test.

 

hi p,
I have read thru the THORLABS documentation regarding the PDA10A2.
As you say they are photo detectors, but they have a built in amplifier, so the signal that you can scope is not the actual response of the PD detector, but an amplified version of the signal, so it is not a 'real' time pulse event.

I will look over the circuit in post #43

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https://www.thorlabs.us/NewGroupPage9_PF.cfm?Guide=10&Category_ID=220&ObjectGroup_ID=3257

 

hi pooya,
Are you aware of this device.?

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hi pooya,
Are you aware of this device.?

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Hello
Yes, I know my major is physics and I have read little about detectors.
But in this work, I need photodiodes and I want to use this piece that is available in my country.

 

hi pooya,
Are you aware of this device.?

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Hello, I had a question?
If the input of my amplifiers is 10 picamperes and my photodiode has an output of 510 nm, will there be a problem for the amplifiers?

 

hi pooya,
The response curves of these two devices are longer than the values you are requiring [ based on your original images]

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hi pooya,
The response curves of these two devices are longer than the values you are requiring [ based on your original images]

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What parameters do you think I should consider to choose a suitable amplifier for my work?

Some datasheets do not say photodiode for use. Is this type of amplifier suitable or not?

Please help me find a suitable amplifier.

 

hi pooya,
The response curves of these two devices are longer than the values you are requiring [ based on your original images]

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Hello
Please, if you can tell me what parameters are suitable for my photodiode that I should pay attention to when choosing an amplifier.
I have already realized that I have to use transimpedance amplifiers.
Please help me choose the frequency and bias current.

 

hi p,
Check these links and PDF.
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https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=285

https://www.digikey.com/en/product-...4300-and-tefd4300f-high-speed-pin-photodiodes

 

hi p,
Check these links and PDF.
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https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=285

https://www.digikey.com/en/product-...4300-and-tefd4300f-high-speed-pin-photodiodes

Hello, I appreciate your help.
Currently, I am away for a few days. I will test it afterward and let you know the result. I have a question for you : Do you think it is better to use OTA or TIA amplifier? I have got seperate suggestions to use both of them but I can not make a decission which one is suitable.
I am sending you names of some amplifiers that I have in access. Please let me know which is more suitable for SFH 2704 photodiode.

 

hi p,
The 'best' from those 4 OPA's is the OPA354, even that one will not meet your pulse rise and fall time requirement.

I would choose a Trans Impedance design

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Update: added PDF

 

hi
I also want to use a second amplifier and increase the output of the first amplifier so that I can have an output of about 2 volts. Do you think I can use AD 8042 friends?
Here I put the simulation for you.