LOG114 for differential voltage input

Discussion in 'The Projects Forum' started by skssks, Jul 20, 2011.

  1. skssks

    Thread Starter New Member

    Apr 6, 2009
    Hi all,

    I have just been introduced to LOG114[http://focus.ti.com/lit/ds/symlink/log114.pdf] and I am building a bioelectric signal amplifier. I am thinking of using the LOG114's A1,A2 and A3 as an instrumentation amplifier and the auxiliary op-amps A4 and A5 for filtering. But when I tried to modify the design for the above operation I am facing a lot of issues like frequency dependency over amplification and log conformity over change in frequency etc.

    Has anyone tried using the LOG114 for such a use instead of the reference current input design ?

    Thank you,


    Last edited: Jul 20, 2011
  2. #12


    Nov 30, 2010
    Perhaps you could clarify your request. What I see is: Hi, I just met a new chip and I want to use it outside its specifications. Without telling you how far outside its specs, can anybody give me advice?

    ps, specsheet attached
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
    Aren't most bioelectric signals bipolar in nature, i.e., swinging both above and below ground? The LOG114 can only accept currents which are into the input pins.