This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LPV821: Designing with LPV821DBVR

Part Number: LPV821
Other Parts Discussed in Thread: OPA320

Hi Team,
We are designing a trans-impedance amplifier using LPV821DBVR in one of our products.
The same is to detect the ambient lighting in a room
The op-amp will be powered from a 3.3V source.
The output we are expecting is in the range of 0.1V to 3.1V.
The selected photodiode is TEFD4300, it has a photocurrent of 17uA, diode capacitance is about 3.3pF.

The circuit is attached herewith, please correct me if there is something wrong.

  • Hi Shibin,

    I normally do not recommend zero-drift (chopper) amplifier for TIA application. The switching effects in the chopping amplifier tend to introduce noise at the op amp's output, especially with larger feedback resistor in TIA application. The LPV821's BW is only 8kHz and chopping frequency is fairly close to the application 's operating frequency. 

    I recommend to use OPA320 instead per the application. I reduced the -3dB pole from  169kΩ||1.8pF (523kHz) to 169kΩ||1.8nf or approx. 523 Hz.  I do not know the required BW of the light detector and you may change per your application requirements. 

    Enclosed are the simulation above and TIA application note. If you have additional questions, please let us know.

    3463.OPA320 TIA 11122021.TSC