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INA149: Distribution Data for CMRR

Sadanori Kato
Guru 36540 points
Part Number: INA149

Hi,

Could you please provide the distribution data for the common-mode rejection ratio within the lots and between the lots to me ?

Best regards,
Kato

  • 0
    TI__Mastermind 23050 points
    Hi Kato-san,

    Could you please elaborate on what you need this data for? I ask because lot-to-lot data is not something that we generally share, and to share this with customers we usually require that an NDA is in place.
  • 0 in reply to Zak Kaye
    Guru 36540 points

    Hi Zak-san,

    Thank you for your prompt reply.

    Our customer is considering that it is to grasp the range of offset variation between devices.
    Then, I will confirm whether NDA has already been concluded and get back to you.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 140200 points
    Hi Sadanori,

    hhm, I agree with Zak. The specifications of minimum CMRR and typical CMRR are such similar, that there should be no need for distribution data. Just take the minimum specification and you are still having a chip with fantastic CMRR. :-)

    Kai
  • 0 in reply to kai klaas69
    Guru 36540 points

    Hi Kai-san,

    Thank you for your reply.

    Our customer would need the distribution data to decide whether adopting INA149.
    Please give me your advice if you have useful information as the high precision would be required for customer's application.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru 67601 points

    Kato,

    Since CMRR in the difference amplifier is determined by the resistor matching, which is trimmed in INA149, there is no difference in CMRR distribution between the wafer lots.  The actual CMRR distribution as well as typical variation of CMRR with temperature is already included in the datasheet - see below:

  • 0 in reply to Marek Lis
    Guru 36540 points

    Hi Marek-san,

    Thank you for your explanation.

    I have one more question, so could you please tell me what "CMRR (uV/V)" means in these graph ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru 67601 points

    Kato,

    A basic definition of the input Common-Mode Rejection Ratio, CMRR, describes how Vos changes as a result of the change in the input common-mode voltage, Vcm: CMRR = ΔVos/ΔVcm
    Thus, if Vos changes by 100uV in response to 10V change of Vcm, then
    CMRR = 100uV/10V = 10uV/V , which may also be expressed in terms of decibels [dB]
    CMRR=20*log[10uV/V] = 20*log[(10^(-5)] = -100dB

  • 0 in reply to Marek Lis
    Guru 36540 points

    Hi Marek-san,

    Thank you for the explanation.

    I understood and will inform this information to our customer.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru 67601 points
    No problem. Good luck.
  • 0 in reply to Marek Lis
    Guru 36540 points

    Hi Zak-san & Marek-san,

    I confirmed NDA has already been concluded with TI, but I will discuss with our customer about the information which you provided to me.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi Marek-san,

    Today, I discussed this topic with our customer, so I will need to provide the more detailed information as he cannot estimate the average value and standard deviation from figure 30.
    I have already sent a friend request to you, then could you please provide the raw data of more than 100 samples for "CMRR vs TEMPERATURE " such as figure 30 via a private message on e2e ?
    If impossible, could you please provide the distribution data of average value and standard deviation after the statistical processing instead of the raw data ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru 67601 points

    Kato,

    We do not have raw data of INA149 CMRR vs Temperature distribution of 100 parts to share with customer and that is the reason why INA149 specification shows only typical 100dB (10uV/V) value - see below.  But since our typical value represent mean+one standard deviation, with a mean being around zero, this means that sigma of CMRR over temp is approximetely 10uV/V.

    What this means is:

    99.7% of all units will have CMRR over temp within +/-30uV/V limit (+/-3 sigma)

    99.99% of all units will have CMRR over temp within +/-40uV/V limit (+/-4 sigma)

    99.9999% of all units will have CMRR over temp within +/-50uV/V limit (+/-5 sigma) 

    Please see Normal Gaussian statistics below:

  • 0 in reply to Marek Lis
    Guru 36540 points

    Hi Marek-san,

    Thank you for your continuous support.

    For CMRR, the minimum value is defined in the following condition, so I am convinced that its distribution data exists.
    In addition, could you please provide the raw data shown in figure 30 since our customer is considering to grasp the distribution data based on the measured data ?

    Best regards,
    Kato

  • 0
    TI__Guru 67601 points
    Kato,
    I have located some original CMRR over temperature characterization data for INA149 but cannot post it on this external forum.
    Please contact local TI FAE, Taketo Sato <taketo@ti.com>, to forward it to you.
  • 0 in reply to Marek Lis
    Guru 36540 points

    Hi Marek-san,

    Thank you for your strong support.

    I understood and will contact Sato-san.

    Best regards,
    Kato