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how to measure current in the TIA

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timedate

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For example, I have two feedback TIAs (with photodiode connected). I want choose the one with large input current signal, and the shunt down the other.

So, I have to measure the average current through the TIA, by means of measure the received optical power.

Does anybody know how to perform this function ? put a ADC connected to the TIA?

Thanks in advance.
 

erikl

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Most simulators can measure the current through any component. If not, you could insert a 0Ω-resistor or a 0V-vdc which by default measure and show the current through them.
 

D.A.(Tony)Stewart

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timedate

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Thanks, but I mean the real circuit, not the simulation. Any hints?
 

KlausST

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Hi,

you want to know the current through the diode?

It is output_voltage / feedback_resistor.
The feedback resistor should be known, the output voltage too, so it is simple math.

Or I misunderstood....?

Klaus
 

crutschow

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Below is the LTspice simulation of a simple two op amp Analog Max. Value circuit, which should have a smaller output glitch when the output goes from one input to the other as compared to a comparator/analog switch circuit.
It's output is the maximum of the two inputs.

What is the maximum frequency of the inputs?

Max Value Ckt.GIF
 

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