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OPA551 common mode levels and noise predictions

bgo
Prodigy 10 points
Other Parts Discussed in Thread: OPA551

HI,

I have a design were I am using the OPA551 as an integrator. Positive supply is at 60V and the negative is at 0V.

The inputs are at +2.5V from the negative supply, which is at the low end of the permitted input range.

My concerns are:

1. Does this low input common mode level degrade input noise levels?

2. Can de device sustain low noise levels over temperatures?

BR

bjarke

  • 0
    Guru 21975 points

    Bjarke,

    The input stage of the OPA551 is cascoded, meaning that the input transistors have virtually the same operating voltage conditions at any point within the common-mode range. I don't expect any significant change in noise at your operating point.

    I expect voltage noise to increase somewhat with temperature, perhaps by approximately 25% or so at the high end of temperature range. Current noise will rise more, increasing by about 3x for each 10k rise in temperature.

    Regards, Bruce