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.

OPA3S2859-EP: Output of the amplifier problem. The voltage is between 100 mV and 600mV max.

Part Number: OPA3S2859-EP


I have a problem with the OPA3S2859-EP (Programmable Gain Transimpedance Amplifier) device.

The configuration used is the one shown in the figure where:
Supply voltage (VS+ - VS-)= 5V - 0V
Output at 50 ohms.
SEL1, SEL0, LATCHA, LATCHB are configurable via pins.
The photodiode used is the Thorlabs FGA01FC.

The output signal without an optical signal is 100mV. I have an offset of 100mV.
The amplifier saturates at about 600mV.
Shouldn't the output signal be between 0 and Vs-0.5? Why the output saturates at 600mV?



  • Hi Nicola,

    you cannot connect the +input and negative supply voltage pin both to signal ground. By this you violate the common-mode input voltage range. In this case you would need to supply the OPAmp by a bipolar supply voltage with the negative supply voltage pin seeing a negative supply voltage and not signal ground.

    Best see the "EVM User's Guide".