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DAC8820EVM Op Amp Upgrade

SSquared
Intellectual 260 points
Other Parts Discussed in Thread: DAC8820EVM, OPA2277, DAC8811, DAC8820

I replaced U5 on the DAC8820EVM from a OPA2277 to a OPA2211. I have installed capacitors on C10 and C6. Both of which are now 10pf. There is a large amount of noise being created. Around 25mV. It is set to the bipolar voltage output at +-10V. Which would have a 0.3mV step for the 16bit application. Is there any way I can get the noise removed and still have a high speed op amp?

  • 0
    TI__Mastermind 46290 points

    SSquared,

    I guess we're still stuck on the DAC8811 problem?

    Ultimately to remove this noise we're going to have to apply some kind of filtering. Filtering is going to reduce the bandwidth of your system, which may eliminate some of the benefits of your high speed amplifier. 

  • 0 in reply to Kevin Duke
    Intellectual 260 points

    Yes, I am still stuck on the DAC8811 problem. I actually switched over the the DAC8820 because I wanted the outputs to happen faster than sending them serially. The process I am doing requires timing to be very critical.

    I am trying to reduce the time of the input signal all the way to the output. Having it operate at 100kHz. The research I am doing has been all in EVMs and bread boarding. Which is proving to be a feat at the 100kHz speed.Why I was trying to upgrade the DAC8820EVM output transistors to be a little more rigorous.