Improved Howland current source

Discussion in 'General Electronics Chat' started by Majjik, Oct 17, 2013.

  1. Majjik

    Thread Starter New Member

    Oct 17, 2013
    1
    0
    Hi guys,
    I need your help a little bit :) Is here anybody who could help me with design - improved howland current source? I need constant current approximately 500uA with 50kHz and the input signal will be 0.5V. I created some source but the problem is that when I use OP177 and I change kHz or R_load the output current have changed, but when I use OPA277 nothing happen and the I(rms) is 491uA.

    Why OP177 does not want to work?

    Thank you very much
     
  2. WBahn

    Moderator

    Mar 31, 2012
    17,788
    4,808
    What's your gain-bandwidth product look like?
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    Both of those op amps should work but you may have problems at 50kHz due to their low gain-bandwidth. Does the OPA277 work with a low frequency or DC input?
     
  4. gootee

    Senior Member

    Apr 24, 2007
    447
    50
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