I need a differential TIA to remove noise with several Mhz frequency bandwidth.
Can i use ad8138? The parameter seems fine to me.
Does it have any other suggestion or is there any problem with this?
Cross talk on most duals is not too bad, but when you have a high speed circuit and have
very low currents from a photodiode or whatever, you can have leakages across the pc board,
etc. With tiny packages, putting a lot of passives around one dual can give you pc board routing
problems. Plus, you might want to guard ring the inputs, etc. and getting traces between pins
can be tough.
In the attachment, the cap value is 7pf,not 1uf. In this case, with 1pf junction cap of PD, the frequency bandwidth is about 8Mhz.
The input bias current is 7 uA. 100k is too big. You really need to use two classic TIAs and then take the difference.
You are right. With this bias current, the output offset is almost 0.7v with 100k.
So do you have any amplifiers suggestion for the two classic TIAs?
Before i was using op470. But it is too slow for this project.
ADA4817-1. Use two. Don't use the dual.
(cross talk, pc board layout, etc)
Thanks for your suggestion.
But you said don't use the dual, because of the cross talk inside the chip?
Got it. Really appreciate it.
Since you have a single ended source, it may be easier to let the op amp to do the SE-to-differental for you. Check this app note out.
Solutions - Single Ended To Differential Transimpedance Amplifier
You don't need the JFET if noise is not a problem for you.
Thanks. I will check that article.
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