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INA116 ECG acquisition

Siyavash Asadi
Intellectual 665 points

Other Parts Discussed in Thread: INA116, ADS1298, INA333, INA326, OPA348, OPA333

Hi,

I am interesting to use TI product as well as I can because of very good documents and support.

In my new project I want to acquisition ECG and may be EEG, but I want do it without digital part so I don’t want to use ads1298 I used it in my prior project, I want to have very good ECG so I chose INA116 because it is an ultra low leakage current INA , but after I studied technical documents and INA116’s datasheet I understood input pin of INA116 is very sensitive so I should use guard shield and other protection. but refer to “Analog Fundamentals of the ECG Signal Chain” PPT ,many protection used for example Protection Diodes, resistor and also Low Pass Filter that all of them I think create and increase input noise and we can’t use benefits of guard and shield. I will be glad if you help me how I can have both ultra low current bias feature and also design protection.

and my other problem is how I can use guard when I am using standard Ag/Agcl electrodes? I have to use special electrode same as active electrodes?

best regards,

Siyavash.

  • 0
    Intellectual 665 points

    it is my second post that no body answer to my question.

    please help me as soon as possible,

    best regards,

    Siyavash.

  • 0 in reply to Siyavash Asadi
    TI__Mastermind 25875 points

    Hello Siyavash,

    Please refer to the following post:

    http://e2e.ti.com/support/amplifiers/precision_amplifiers/f/14/p/265739/930235.aspx#930235

    Please be sure to check out this Wiki page:

    http://e2e.ti.com/support/amplifiers/precision_amplifiers/w/design_notes/2437.ecg-heart-signal-acquisition.aspx

    That said, I do not think you require the ultra-low input bias current of the INA116 for ECG, and perhaps even for EEG (even with dry/non-contact electrodes).  I seem to recall reading journal papers to this effect out of UCSD by Mike Chi and Gert Cauwenberghs.

  • 0 in reply to Pete%20Semig
    Intellectual 665 points

    Hi Pete,

    thanks for your good advice, my final project in B.Sc was contact-less electrode and I read all of the paper in this field. but in my new project I have to use passive electrode so input noise is high, I used INA326EA but my result in real test wasn't good. I read INA333 datasheet and I think it's parameter is very near to INA326. my question is, is it possible to offer me better INA.

    and the other question. I saw that for RLD in some AN used OPA348 and in most case used OPA333 but I don't know why? and which one is better for this application and what is benefit of them than the other?

    Sincerely yours,

    Siyavash.