Improved Howland current source

Thread Starter


Joined Oct 17, 2013
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



Joined Mar 14, 2008
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?