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slide 10102 l9 K4 T& h! U# w5 G
; ?) m* m( C( Z4 \6 @8 |3 kFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. 0 ^4 j; ]5 ]$ h
The signal bandwidth is determined by RF and not by the circuit gain.
6 R: Q6 O# I1 hThe circuit gain is independently set with RS.
3 b3 k" W. U" fThe signal bandwidth remains stable for all gain settings .
% y$ r, [5 Q5 j/ T2 ~Even for unity-gain operation, an RF resistor is required.
$ N2 E k7 d- ^, |3 PThe 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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