Jump to content
Electronics-Lab.com Community

How To calculate the feedback resistors in an OpAmp Amplifier?


Recommended Posts

Hi

Imagine that you want to build an Inverting OpAmp Amplifier with the Gain of 30. What is the difference if I choose two resistor as

(Rf=100K, R1=3.3K) or  (Rf=10K, R1=330R). In both cases the Gain is 30, but In what conditions, does it make difference? and what about a Non-Inverting One?

ThanX
Shahriar

Link to comment
Share on other sites


You are changing the input resistance and thus changing the input impedance. The input resistor could also be used as part of the input filtering such as a resistor/capacitor filter. The value would need to be correct for the cut point. In all cases, the input resistor is determining the current (V/R=I). All of the above are the reason that it makes a difference. You should design with all of these items in mind.

MP

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
  • Create New...