Do OpAmps manufactured on same si wafer (in same IC package) have similar V Offsets?

Discussion in 'General Electronics Chat' started by InsaneBrain, May 1, 2013.

  1. InsaneBrain

    Thread Starter New Member

    May 1, 2013
    1
    0
    Hi all,

    I am an electronics student attempting to design an EEG system that will be able to capture signals in the 100-500 nV range with a bandpass around 0.5-400Hz. A huge issue though is that, since the differential signal is very small, and the Common mode signals are very large, tiny voltage offsets (Vos) on my Preamps show up in the gain stage of my instrumentation amplifier.

    Now, from my understanding, the Vos of opamps are the result of imperfections in the silicon wafers used in the IC production, so I thought if I run the signals from both electrodes into one IC with two amps, even if the Vos is larger than the signal, they would be equal, and rejected as common mode signal. So my question is:

    "Are the Voltage Offsets of amplifiers made on the same silicon wafer (two opamps in one IC package) equal?"

    Thanks for answering my first post to AAC!
    InsaneBrain
     
  2. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    No, not equal. Product datasheets give you the maximum offset voltage for the opamps. Best you can expect is they are all within the maximum VOS.
     
  3. #12

    Expert

    Nov 30, 2010
    16,346
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    Last edited: May 1, 2013
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