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ADS1293: Noise specification

Takumi Suzuki1
Mastermind 8680 points

Part Number: ADS1293

Hi,

I would like to ask you a question about Ve-ECG and Ne.

I do not understand the meaning of "Ve-ECG" specification well, datasheet page 6.

Why do you define this specification?

How should I understand the relation between Ve-ECG and Ne?

Would you give me any advice to understand correctly?

Best Regards, 

  • 0
    TI__Mastermind 38745 points
    Hello Takumi-san,

    Ve-ECG is the peak to peak noise measured for the bandwidths shown in the "test conditions".

    Ne is the spectral noise density for those bandwidths. Spectral noise density is defined as the amount of noise power per unit sqrt(Hz). To calculate noise density from noise, take Ve-ECG, which is pk-pk, convert it to RMS by dividing by 6.6, then divide it by sqrt(bandwidth). For example, for Ve-ECG, 0.1 - 215 Hz, high resolution mode: 15 uVpp/(6.6xsqrt(215 Hz)) = 155 nV/sqrt(Hz) which is what is shown for Ne below.

    Brian
  • 0 in reply to Brian Pisani
    Mastermind 8680 points
    Hi Brian-san,

    Thank you very much for your kind reply.
    I understood well.
    But let me confirm again if my understanding is correct as below.

    As Ve-ECG is p-p noise, this value is related with "Noise free bit" and Ne is related with "ENOB", I think.
    Is my idea correct?
    That is to say, for example, "ENOB-ECG" 17.8bit@215Hz is caluculated from Ne value, right?

    Generally speaking, "noise free bit" value is smaller than ENOB value.
    Which index should I consider to design?

    I appreciate your support.
    Best Regards,
  • 0 in reply to Takumi Suzuki1
    TI__Mastermind 38745 points
    Takumi-san,

    ENOB is not related to Ne. Generally Ne is not useful if you know Ve-ECG. Table 8 - Table 11 give the RMS noise for the different data rate configurations. This will be useful to determine the dynamic range and ENOB for different data rates.

    Brian
  • 0 in reply to Brian Pisani
    Mastermind 8680 points

    Brian-san,

    Thank you so much!

    I understood.

    Regards,