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slide 1010; R" X/ E+ {# ^. a
6 e1 Z' d$ q" `
For a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
4 F' B1 U1 e2 ~7 ^. C; n+ }) mThe signal bandwidth is determined by RF and not by the circuit gain.$ Q/ { l, }: V$ l
The circuit gain is independently set with RS.9 t7 E2 O" ~& I$ m! `6 y
The signal bandwidth remains stable for all gain settings .3 \9 A( J$ {. R: K! j; n) q
Even for unity-gain operation, an RF resistor is required.
6 M3 i* b5 b. p) e" M- f p9 |The best practice when designing with CFB op-amps is to use the RF values given in the datasheet and to adjust the desired gain level through RS.9 d: H3 J5 e, X/ d
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