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Original question:

OPA192: About Test conditions

OPA192: how to improve the noise level of OPA192?

du zhang
Intellectual 580 points
Part Number: OPA192
Other Parts Discussed in Thread: OPA2192

Dear sir

    l use the opa192 as voltage signal amplifier ,the schematic is as follow ; when I short the opa192 output to ground ,the noise figure is picture 1, when the opa192 work on the system ,the noise figure is picture 2,

can you help to check and give some suggestion to improve the noise level of opa192?

picture 1

picuture 2

  • 0
    TI__Guru 68021 points

    When you short the OPA192 output to ground, the output is in a short-circuit protection mode and thus your noise-gain goes down - this is the reason why you see lower noise level in the picture 1 - however, this is NOT a linear operation.  The output noise can be lowered by lowering its noise gain (lower feedback resistor), filtering it with a feedback cap like C14, or a lower cut-off frequency of low pass filter, R15/C16.  But regardless what you choose to do the noise will always be lowered with the OPA2192 output being grounded but this is not a valid condition.