AD7124-4 rms noise

Hi

I have a question regarding noise values are tabulated in the data sheet.

For example in the case of Sinc3 filter (Full power), the noise value is reported as 0.23 (µV) and 0.023 (µV) respectively Gain=1 and Gain= 64.

From best of my knowledge the noise voltage will be increased through the amplification. Therefore, I expected the noise value to be higher for higher Gain.

It would be very nice if you can help me with the answer.

With the best regards.

  • +1
    •  Analog Employees 
    on Feb 16, 2021 3:39 AM

    Hi, 

    I think that is one of the key benefit of AD7124, we designed PGA so that signals of small amplitude can be gained within the AD7124 and still maintain excellent noise performance. 

    At gain=1 the two PGAs are bypassed so you are expecting that the noise at Gain=1 is higher but the consumption is much lower as compared to higher gains. I cannot really explain in details how the part do it as it is protected by our design. But the datasheet provide all of the specifications  needed across different gains.  

    Thanks,

    Jellenie