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Hello,
the output of TIA is 300 mv , i am feeding to op amp negative terminal , and Op Amp(LOW POWER) configuration is shown attached ,
but the problem , what ever be the input to Op amp i should get inverted of it, but as strange i got 4.97 v . which should not be the case, what is the reason for that , how to overcome that issue
Thanks
Solved! Go to Solution.
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The Opamp is latched up because you have positive fdbk around it.
Eliminate the fdbk path from NI to Output of ther OpAmp, double click
it, set it to a follower. Run TIA output into NI input of follower. But TIA
is itself buffered, you should not need a OpAmp follower.
If you need to invert the TIA output then use a PGA as an inv amp.
Or reverse TIA input current.
Regards, Dana.
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The Opamp is latched up because you have positive fdbk around it.
Eliminate the fdbk path from NI to Output of ther OpAmp, double click
it, set it to a follower. Run TIA output into NI input of follower. But TIA
is itself buffered, you should not need a OpAmp follower.
If you need to invert the TIA output then use a PGA as an inv amp.
Or reverse TIA input current.
Regards, Dana.
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hello dana,
Used Inverting PGA , this having Maximum OFFSet, which is killing the real signal
Thanks
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What is the input to the TIA ? Schematic if you have one.
Regards, Dana.
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If you are facing Offset issue, try adding a DAC to compensate it.
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The DAC brings its own set of offset and gain problems with it,
do an end to end error analysis to see how this substantively this
will not work.
A classic method of getting rid of offset is to use a S/H to capture the
offset, and subtract it out.
Another very effective method is correlated double sampling -
http://www.cypress.com/?rID=49159
Regards, Dana.