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Winterstone said:Q3: The term you call "attenuation" is nothing else than (and should be called so) the "feedback factor FB or beta" with FB=Ri/(Rf+Ri)
*For non-inv. opamp amplifiers and signal input directly at the pos. terminal: Gain G=1/FB (idealized opamp properties).
*For inverting opamp amplifiers and signal input at Ri (connected to the inv. terminal); Gain=-FF/FB with FF=Feedforward factor=Rf/(Ri+Rf)
(the incoming signal is reduced before it enters the inv. opamp input). Thus: G=-Rf/Ri.
PG1995,
again you are using the term"concept of attenuation" - is this used in your book? Didn't it use the phrase "concept of negative feedback"? Indeed, this would be more suitable.
The open-loop bandwidth is equal to the ratio (GBW/open-loop gain Aol) which gives approx. 10 Hz only.
Now the calculation:
Assuming a min value GBW= 500,000 and a closed-loop gain of 50 the closed-loop bandwidth is 10 kHz.
This does not fulfill your requirement (gain of 50 for 20 kHz).
For a GBW=1.5 Mhz the closed-loop BW for a gain of 50 is 30 kHz.
Thus, the 741 opamp can fulfiil your requirement only if the GBW value is approx. at its max. value.
By the way: Who is the author of that book?