current to voltage converter

Discussion in 'Homework Help' started by Mabunda, Mar 10, 2004.

  1. Mabunda

    Thread Starter New Member

    Mar 9, 2004
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    What must i consider when using current to voltage converter, and what are the op_ amps parameters must i consider or perhaps help me with good transducer
    amolifiers.

    Thank you
    Themba Mabunda : :lol:
     
  2. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    :) hi,

    here's a few things you should consider when you are going to use op-amps,
    1. Vcc
    2. slew rate
    3. frequncy response
    4. closed loop response
    5.output impedance vs. frequency
    6. relative frequency response vs.frequency
    7. low noise or ultra low noise

    many more.......... :)

    whatever op-amp you will use, read very well the datasheet and you will get what the best and worst of the op-amp you are using :blink:
     
  3. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    In addition to what mozikluv has said, have a look at the Transresistance Ampilfier.

    It is essentially a current to voltage convertor which takes an input as a current and produces a voltage output. For all intents purposes its very like an inverting amplifier and considerations should be given as if it were an inverting amplifier.

    If I can find a link to the Transresistance amplifier I will post it up for you to have a look.
     
  4. haditya

    Senior Member

    Jan 19, 2004
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    :huh: someone help me on this what does one mean by a "current to voltage convertor" :unsure:
     
  5. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
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    :) hi mabunda & haditya,

    try this sites about transresistance amplifier

    http://ieeexplore.ieee.org/xpl/abs_free.js...arNumber=658624
    http://www.engin.umd.umich.edu/~fmeral/CIR...t%205/Opamp.pdf
    http://grove.ece.iastate.edu/docs/papers/20000806.pdf

    you will learn a lot about transresistance amplifier.

    have been using these as part of my audio power amp designs. :) however based on your qualification as you have mentioned in one of your post, that topic might be out of your range but it does not mean you won't understand any of them. :)
     
  6. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    A current to voltage convertor is essentially a device which takes a current as an input and provides a voltage as an output.

    Look here about a third of the way down the page to see a basic model for a current to voltage convertor, remember this doesn't necessarily represent what is inside such a device. There also some information on a voltage to current amplifier (or Transconductance Amplifier).
     
  7. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    :) hi mabunda,

    since you are in astage where you want to build your project, your choice of using a current feedback amp. is just right in converting the small output current of a photo-diode transducer to a fast responding voltage.

    what should really concern you what component values should you use on your resistors and capacitors. with a CFA it has an internal buffer at the inverting node of the op amp and internal output impedance (Ro) (this can be seen in the datasheet in whatever CFA you will use). the photo-diode has an output capacitance of about 10 - 200pf which introduces a zero gain at about 1/2piRoCin.

    for you to counteract the effect of zero gain you have to use a feedback capacitor in parallel with Rf. this way you're introducing a low frequency pole as determined by this equation 1/2piRfCf and an inconsequential zero determined by this equation 1/2piRoCf

    if Cin is large enough, say 0.1uf or 0.15uf the closed loop phase shift will be approaching -180 degrees at the cross-over frequency where open loop transimpedance gain will cross the noise gain function.

    at the output put an RC filter

    if i sound greek, just holler, we will just have to try another approach. :)
     
  8. sjoshidce

    New Member

    Sep 18, 2006
    1
    0
    hi,
    plz send me cicrcuit for current to voltage convertor

    thanks
    sunil




     
  9. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
  10. kender

    Senior Member

    Jan 17, 2007
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