Slew rate or bandwidth?

[steadyj]

slew rate bandwidth

Hi,
When considering speed of OPAMP, there are two parameters of slew rate and bandwidth. My gut feel is bandwidth is a very clear concept, because it is based on the solid Fourier theory. But I have no sense of slew rate. Is there inherent relation between them? Which one is more effective in a certain context?

Thanks,
Steadyj

 

[flatulent]

increase slew rate

Slew rate is dependent on the current available at an internal stage to charge and discharge a capacitance. It will set the large signal frequency response.

 

[steadyj]

slew rate vs bandwidth

So for large signal, the transition speed of OPAMP is limited due to slew rate rather than bandwidth? In other word, slew rate is a lower limit than bandwidth for large signal?

 

[eecs4ever]

slew rate and bandwidth

yes

 

[watersky]

slew rate and banbwidth

slew rate is large signal, bandwidth is small signal

 

[Audioguru]

how to increase slew rate

The lousy old 741 opamp has an output of 28Vp-p up to 9kHz. Higher frequencies are distorted into triangle-waves with reduced peak voltages.

But it still has plenty of gain up to about 100kHz where its max undistorted output is only 3.5V p-p.

 

[desperado1]

slew rate bandwidth calculation

Is there a way to increase the slew rate...........i mean to nullify the effect of slew rate ??

 

[LvW]

slew rate bandwidth

Is there a way to increase the slew rate...........i mean to nullify the effect of slew rate ??

No, you can´t "nullify" the slew rate.
The value of SR is determined by the compensating capacitor within the opamp.
If you need higher SR values, use opamps with external frequency compensation capability and compensate only as large as necessary for the corresponding gain - or use current feedback amplifiers.

 

[PaloAlto]

increasing slew rate

Is there a way to increase the slew rate...........i mean to nullify the effect of slew rate ??

No, you can´t "nullify" the slew rate.
The value of SR is determined by the compensating capacitor within the opamp.
If you need higher SR values, use opamps with external frequency compensation capability and compensate only as large as necessary for the corresponding gain - or use current feedback amplifiers.

We have already had this conversation two months ago. There are ways to increase Slew-rate beyond the recommendations that LvW gives. you can read the converstion here:

 

[LvW]

slew rate vs. bandwidth

...................
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We have already had this conversation two months ago. There are ways to increase Slew-rate beyond the recommendations that LvW gives. you can read the converstion here:

Hey, PaloAlto !
Of course, you are right. However, I think we have to distinguish between two cases:
1.) Determining the slew rate SR by modifying the internal structure of the opamp
2.) Change of the SR for a commercial opamp from the stock.

The reference mentioned by you refers to case 1) whereby, most probably, the question from steadyj belongs to case 2.) .

 

[PaloAlto]

bandwidth vs slew rate

You are probably right, I tend to think in terms of IC design

 

[xulfee]

slew rate effect

slew rate simply means how much ur output is following ur input,bcoz ur output doesn't follow input for high frequency bcoz of circuit complexity