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OPA862: Question about fully differential inverting amplifier configuration.

Hojoong Kim
Prodigy 10 points
Part Number: OPA862


Tool/software:

I want to use opa862 as a differential adc input driver. My signal is in the range of 0-5V and the ADC input range is 0-2V.

So I conducted a Tina simulation using opa862 as an inverting amplifier.

The results of the simulations are satisfactory; however, they are implemented in real hardware and oscillation occurs in the output pins during the operation of the corresponding circuit.

I wonder if oppa862 doesn't fit my application. 

I'm asking for someone's help with the difference between simulation and actual hardware operation.The symptoms are the same even on bare boards.

  • 0
    TI__Mastermind 18045 points

    Hi Hojoong,

    I was looking over your Tina circuit and was curious if this is how the real-life circuit is implemented? If so, the design is likely not to work as this specific device is meant to be configured somewhat different than your typical FDA configuration which does use two feedback looks like you did in the TINA sim. If you refer to Figure 8-1 in the datasheet you can see that the internals are slightly different than a typical FDA. This device does not require a feedback loop from the negative output to the input only from the positive output to the feedback pin like the figure shows. 

    Best regards,

    Ignacio