STILL NOISE IN THE SECOND COLUMN (GOOD)

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Anonymous
Not applicable

Thanks about the Enoa parameter. The datasheets states:       

   

ENOA Noise at 1 kHz (Power = Medium, Opamp Bias = High) – 100 – nV/rt-Hz       

   

But anyway, I introduce  a sinusoid into a PGA follower  (Gain=1) and apart  I monitories the input and output in the First column and I get the image 1, obtaining the expected.       

   

Input=Output (Port 0_3)       

   

(Vsin input= 500Hz 1Vpp and 1Voffset)       

   

When I did the same in the second row I got a noisy sinusoid  output.  The output is equal to the input but the noise is much higher than the specifications told in the datasheet, so I still thinking my part is damaged.       

   

Image 3 shows the add noise is around 800KHz and 1MHz.

   

       

What do you think about it?       

   

Is damaged my part?

   

       

        By the way, I have a RC filter in my Port 0_5  board outout.       

   

Could it produce the noise?

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MR_41
Employee
Employee
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Do you have a capacitor directly tied to the output pin and the AGND?  Or if the R in the RC filter is too low, the capacitance on the pin will make the analog output buffer to behave like an oscillator.  Remove the capacitance on the pin and that will solve the problem.

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Anonymous
Not applicable

Was your problem resolved?

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