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slide 1010+ B6 t/ `% T3 i* ~& {) ~ M
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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. / A% L' S, [) o% y1 I
The signal bandwidth is determined by RF and not by the circuit gain.
$ @% t( T. j8 ~5 C0 t$ iThe circuit gain is independently set with RS.
1 D2 [% k8 A" K- V% l. _ nThe signal bandwidth remains stable for all gain settings .% y \+ J8 c5 q! C3 a& S/ s
Even for unity-gain operation, an RF resistor is required.: ]5 f5 Y, o1 Z/ V9 ^. h4 u
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.2 \% v% p. j# Q0 }1 m
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