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Tool/software: TINA-TI or Spice Models
Hello;
I have a 1 photodiode and 1 Avalanche photodiode.
I have tried OPA857 before but I need to design new pcb for my application.
First I want to build TIA and second stage amplifier for 0-200Mhz signal
For the Photodiode(FGA01-Thorlabs) I am unable to choose even though I almost memorize the Opamp specs.
First of all I am in between OPA656-OPA843-OPA847- Opa381(I prefer msop package) and for second stage THS4504 Seems fine to me but I am not sure. After the second Stage I will use Microcontroller for Signal processing.
For the Avalanche Photodiode(G8931-10 Hamamatsu)
I though I can use same opamps but Still I am not sure. The bandwith is the same as photodiode. I also used Opa857 before for this application.
But I am open to any suggestion about my design.
The light I am trying to detect has really low illumination.
Thanks in advance.
Best regards
Hello Ali,
So in summary, if you constrain your min Cf to 0.2pF the OPA847 and OPA855 give about the same noise but the OPA855 is being underworked with both designed for 5kohm. If you can deliver lower Cf, then the OPA855 becomes more attractive. The LMH6629 is less attractive due to its higher input C increasing the peaking part of the noise contributions.
See attached.
Some APD front end amps for an APD application.docx
We have been presenting this transimpedance design flow for many years, shows where the equations come from - and why the simplified noise expression might be enough.
Hello Mr. Micheal Steffes;
I am trying to design as you suggested I will try Opa855 but I will also try to Opa847, For a second stage, I will try to integrate LMH6554.
Do I need to integrate additional filtering because of my frequency bandwidth?
Thanks for your all answers I am reading, again and again, all of them.
Best regards.
Hello Ali,
I got a little ways into TINA sims on this, and I don't think the full model of the OPA847 has quite enough for what you need. I was going to go on to the OPA855 for a bit this morning. Also, I have abandoned the LMH6554 in favor of the LMH5401.
This is going to be pretty noisy due to how wideband it is, some passive filtering will be required out of the last stage to control the integrated noise - is this DC coupled? If not, what min max band do you want? And is this heading to and ADC, need to set up Vcm on that as well and include input C in filter design - which ADC?
Ok Ali,
I worked through quite a few issues to get to a final proposal - this should get you going for now - will undoubtedly need to be tweaked but I have to step off to other things for now. This is pretty fun stuff though for me.
The word file steps through the stages, with the final full circuit below that - can only attach one TINA file at a time.
Hello Mr. Micheal Steffes;
I have just looked at the design file and analysis You have sent me. I am really grateful for Your concern.
No words can express my gratitude to You.
Thank You over and over again.
I have learned at least 3 month worth of research knowledge. And the design is on another level for me and just examining them unbelievably fun for me cause it has a lot of good touch
In our culture When a person teaches you to some stuff, It means the world to us. Thank you again.
I am a research assistant in Turkey. If you ever visit Turkey I would want to show my gratitude. Please contact me.
Best regards.
Hello Mr. Michale Steffes;
Thank You again and again.
I am trying to explore the design further. And I am also enjoying.
It is a tough one but I believe I can do it with your help now.
Thanks in advance.
Best regards.