I am trying to operate the OPA657 as a trans-impedance amplifier, but I am not able to get it to work. any help
What specifically is not working? If you upload your schematic we can take a better look at the problem.
There are also a couple app notes that might help you get started:
Regards,Luke LapointeHigh Speed Amplifiers
Regards,Luke LaPointeHigh Speed Data Converters
In reply to Luke LaPointe:
Please refer to page 11 figure 3 in the datasheet of the OPA380. I am using the same schematic. I couldn't get it to work properly. I replace many of it, but every one gives different random and strange results. one of them gave 5V DC output modulated by my square wave light signal.
In reply to Khaled M. Dadesh:
Did you mean figure 3 of the OPA657 datasheet?
If so, the compensation capacitance could be an issue here. The feedback capacitor was chosen based on the input diode having a 50pF of capacitance. If this value changes, you will have to recalculate the value of the feedback capacitor again.
What is the capacitance value of your input diode?
Try cleaning PSB with alcogol (CH2 H5 OH). On PSB may suffisient stray resistanse with dirt.
In reply to Georgy:
Thank you for your advice. I was able to get it to work now, and it looks that there was soldering issues.
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