OpAMP: Inverting or Non-Inverting?

[unkn0wn]

op amp non inverting amplifier

Which configuration has best frequency response Inverting or Non-inverting and why?!

 

[LvW]

inverting unity gain

Which configuration has best frequency response Inverting or Non-inverting and why?!

1.) If in both cases the feedback resistors are identical, the loop gain is identical and, hence, both have the same corner frequency (but the gain differs by "1")
2.) If the gain in both cases is identical, the resistor ratio differs and, hence, the loop gain is smaller by "1" for the inverting configuration. Therefore, the corner frequency is slightly reduced for the inverter.

 

[unkn0wn]

advantage of non inverting

So, Can i Say that both are same?

(the +1 can be neglected)!?

However, on page 93 of Microelectronic Circuits by Sedra Smith 5th edition, it is stated,

"The unity-gain inverting amplifier has a 3-dB frequency of (unity-gainbandwith)/2 as compared to unity-gain bandwidth for the unity-gain non-inverting amplifier (the unity-gain voltage follower)".

What does this mean?

 

[LvW]

inverting gain

"The unity-gain inverting amplifier has a 3-dB frequency of (unity-gainbandwith)/2 as compared to unity-gain bandwidth for the unity-gain non-inverting amplifier (the unity-gain voltage follower)".
What does this mean?

In this special case (unity gain means gain of "1") the "1" I have mentioned (and which you propose to neglect) is identical to the total gain leading to a factor of 2 in bandwidth. That´s the whole secret.

 

[unkn0wn]

unity gain inverting amplifier

In this special case (unity gain means gain of "1") the "1" I have mentioned (and which you propose to neglect) is identical to the total gain leading to a factor of 2 in bandwidth. That´s the whole secret.

Which means, in this particular case, non-inverting is twice better compared to inverting? (Yes/No)

And if i am answering a choose the best, for best frequency response either chose (a) Non-inv* (b) Inverting? (b) Both same/almost same?! What should I answer?!


PS: I understand the reasons your provide, but i am forced to chose one..
Edit: thanks for the help so far, clicked helped me

 

[eem2am]

op amp inverting amplifier

hello,

it does not matter the configuration.....you just find that unity gain bandwidth graph and go by that....the frequency response of op-amp is affected by capacitors inside the op-amp.

find your gain...then get the datsheet and trace that gain to the bandwidth.

 

[LvW]

+opamp +non inverting amplifier

Quote:
Which means, in this particular case, non-inverting is twice better compared to inverting? (Yes/No)
And if i am answering a choose the best, for best frequency response either chose (a) Non-inv* (b) Inverting? (b) Both same/almost same?! What should I answer?!

Yes, its definitely true: For unity gain operation (gain: +1 resp. -1) the noninverting circuit has a bandwidth app. twice as large as the inverting response.

The second question is a bit unclear: What means "best" ? Largest bandwidth ?
Could be. But it could also refer to a smooth gain response in the pole region.
And in this case the inverting circuit could have a small advantage as the gain peaking (which eventually can occur) is a bit lower than for the non-inverting case.

 

[chandra.prakash]

Non inverting amplifier is always better than inverting amplifier for the same gain if the input voltage variation is within opamp input common mode range and if sign of gain is irrelevant. There are several reason for this:

1)for the same gain non-inverting amplifier has higher bandwidth
2)input offset voltage and input reffered noise at opamp input get higger gain (1+R2/R1) than input voltage (-R2/R1) in case of inverting amplifier and hence degrading Signal to noise ratio at output.
3)input impedance of inverting amp is R1 which has to be made larger for higher input impedance whoch in turn requires larger R2 for the same gain. This might saturate the output due to offset current through R2. Also thermal noise associated with high R2 would be higher.