Comments on TIA Frequency Response
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TIA Frequency Response
I am designing a TAI using this tool from Analog devices. The circuit diagram and it's frequency response obtained from the design tool is given below.
Circuit Diagram:
Frequency Response
I simulated the same circuit in LTspice the only change I made is instead of dual supply I used single supply.I did not considered photodiode capacitance here.I will be biasing the photodiode as as shown in the first image.
In my circuit I am getting a bandwidth of only 10Hz!!!. Please find my simulation results below.The simulation file is also attached here.
May I know where I went wrong.
When I kept16nF.The simulation is failing
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The following users marked this post as Works for me:
| User | Comment | Date |
|---|---|---|
| newbie |
Thread: Works for me I changed M to Meg I am getting a bandwidth of 1M. |
May 30, 2025 at 12:39 |
The mistake you made seems quite trivial. LTSpice recognizes your 20M as 20mHz (milihertz). If you want 20MHz, then you need to write "20MEG". That's all.
However, when I ran your schm, I got a bandwidth of about 1MHz, which didn't make sense, as I expected a pole at about 430kHz with a 1st-order roll-off. There seems to be some extraneous zero that cancels this pole and it rolls-off with the op-amps parasitic poles (~-40dB roll-off, so 2nd order).
That's as much as I found out. You probably have to characterize the op-amps in LTspice and in Analog's website to see who's wrong. But by the looks of it, I'd tend to trust the Analog's website one.
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