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: n5 x( ]- X* a% l0 HFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. t W s9 m' }- Z
The signal bandwidth is determined by RF and not by the circuit gain.
+ @% N# r5 c5 Y5 z" qThe circuit gain is independently set with RS.
) z' c# i6 a% \" G3 {) gThe signal bandwidth remains stable for all gain settings .9 b! X, @2 m. M, a/ [! x* ~0 a
Even for unity-gain operation, an RF resistor is required.
3 m. `- c+ D- A* {7 qThe 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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