Input Bias Current & Offset Voltage measurement of an op amp

Discussion in 'Homework Help' started by E&C Genius, Apr 25, 2011.

  1. E&C Genius

    E&C Genius Thread Starter New Member

    Joined:
    Dec 9, 2009
    Messages:
    10
    Location:
    Jeddah, Saudi Arabia
    Hello,

    I want to measure the Input Bias Current and the Offset Voltage of an op amp for my electronics lab experiment. I tried to design a circuit for that purpose but it didn't work on (Multisim software), so obviously I didn't build it.

    I've found this PDF online; and as you can see on page 4 it suggest a way to measure them. But I couldn't understand how exactly can I do it?

    Please help me with a suitable circuit or an explanation for the one in the PDF.

    Thank you.

    Attached Files:

  2. beenthere

    beenthere AAC Fanatic!

    Joined:
    Apr 20, 2004
    Messages:
    15,815
    Location:
    Missouri, USA (GMT -6)
    Figures 4 & 5 in the article describe how to measure the input bias current. It looks as if all you need to do is to duplicate the setups given in the file. really nothing to design.

    Can you be specific about what is causing you difficulty?
  3. wmodavis

    wmodavis Active Member

    Joined:
    Oct 23, 2010
    Messages:
    609
    Location:
    Colorado, USA
    The basic problem of measuring input bias current is:
    Because these bias currents are so miniscule they defy direct measurement. You cannot simply insert an ammeter in series and get the measurement you want because the currents are virtually zero compared to those we usually measure. Just try to find a femto-ammeter. Therefore it must be measured indirectly and determined by calculation. Accuracy of the determination is dependent on many factors which must be carefully and accurately measured and controlled.

    Good luck.
Similar Threads
Forum Title Date
Homework Help BJT input voltage definition Today at 4:43 AM
Homework Help Simple 3 inputs AND Circuit Aug 18, 2014
Homework Help Multi-stage BJT Amplifiers Input Resistance Aug 16, 2014
Homework Help What does 50ohm input/output resistance mean on a oscilloscope? Jul 18, 2014
Homework Help Understanding Integrators and Input Offset Voltage Jul 8, 2014

Related Site Pages

Section Title

Share This Page