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For a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
2 g0 U: S1 A: ]1 sThe signal bandwidth is determined by RF and not by the circuit gain.4 L1 ~9 N( T/ e1 w! ~) O; ?* F
The circuit gain is independently set with RS.
3 }8 {# T8 e6 A$ j7 v1 iThe signal bandwidth remains stable for all gain settings . j a& L, m8 _1 i! r
Even for unity-gain operation, an RF resistor is required.
6 p5 d [% Y0 k( ^2 b, w, AThe 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.
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