Re: Op amp newbie

Mac wrote:

> On Wed, 29 Jun 2005 06:29:12 -0700, Yvan wrote:
>
> > Hi,
> >
> > I have a very simple question to ask. Say my required Gain-bandwidth
> > product is 1kHz * 1 = 1k, what is the minimum gain-bandwidth product of
> > the op amp in order to assume an infinite gain?
> >
> > In the book "sensors and signal conditioning", they gave an example of
> > an application that had a GBW of 30 Khz. It mentioned that a opamp GBW
> > of 5 Mhz was large enough to assume infinite gain. 5 Mhz/30khz=167
> > times. Is there a rule of thumb would help in figuring if a given
> > opamp is suitable for my application in terms of GBW?
> >
> > Thank you,
> >
> > Yvan
>
> It depends somewhat on what you are doing.
>
> 10 or even less might be good in some cases. I imagine that 1000 would be
> good enough all the time.
>
> The problem is that as you get closer and closer to the limit, then there
> will be less and less feedback available to linearize the circuit at
> higher frequencies and you will have more and more distortion. If the
> op-amp is followed by an aggressive low-pass filter, the distortion might
> be tolerable, since the filter will knock it down quite a bit.

Filter ?

What filter ?

Graham

.

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