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How can i have a non inverting op amp circuit with a gain of

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blindside

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How can i have a non inverting op amp circuit with a gain of 20?
 

Re: How can i have a non inverting op amp circuit with a gai

just take care that the ratio of the feedback resistor by the resistor to ground at the negative terminal is 19....... that is all...
 

Re: How can i have a non inverting op amp circuit with a gai

blindside,
Let Rf be the feedback resistor.
Let Ri be the "input" resistor. This is the resistor that goes from the inverting input to ground.
.
The closed loop gain is 1+(Rf/Ri).
.
Pick a value for Rf.
Solve for Ri:
Ri = Rf/(Acl-1)
Where Acl is the desired closed loop gain. In your case Acl = 20. So Ri =Rf/19.
Regards,
Kral
 

Re: How can i have a non inverting op amp circuit with a gai

See the attachment...
Non Inverting OP AMP gain is:

A=1+R2/R1

and the rest procedure is the same as describe above.
 

is ther a restriction in the value of resisitors.That was one of the fav questions of profs...where in a high gain reqrmnt is given and one is asked to design the amp with restrcn in values of resistors.
The feedback should be lowered by a T divider configuration
 

Re: How can i have a non inverting op amp circuit with a gai

Sure, there are ranges for these resistor values, and the ranges are different from specific opamp model to other model.

Ri and Rf must not be so small that may make the previous stage output overloaded, while must not be so big that make the opamp itself become unstable due to its input leakage current as well as the the leakage current of the PCB.

For example, for the 741 op amp, Ri must not exceed 100kohm, and Rf must not exceed 1Mohm.

Learn well the datasheets and application notes/examples for each type of op amp for the best practical designs.

nguyennam
 

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