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slide 1010+ V* k1 Z2 y. {- w% ^ F
) F+ K2 \6 r7 E# R8 JFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
) i+ l- y: ~. o$ L' vThe signal bandwidth is determined by RF and not by the circuit gain.: h/ m# b7 h4 o) I/ c& h+ i! l9 }+ V4 G
The circuit gain is independently set with RS.
1 K8 C4 b4 o1 g0 {. k, T+ c3 I$ u! {5 yThe signal bandwidth remains stable for all gain settings .
% H0 f9 s0 [8 R) Z- FEven for unity-gain operation, an RF resistor is required.0 {+ A- Q. _) W" e% e
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.! p8 ^' }1 q' ^
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