slide 1010 / D- P0 \( X+ T9 ]/ f( R& g' y1 ^* S( X Q
For a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. . o5 b8 p: T$ H- }The signal bandwidth is determined by RF and not by the circuit gain.' d; _7 ]) c- }: N- T3 b6 t
The circuit gain is independently set with RS.% K1 [4 n4 Y7 h8 O \
The signal bandwidth remains stable for all gain settings .4 h+ T5 M9 v$ u0 s8 A
Even for unity-gain operation, an RF resistor is required. ( u' Q" e3 E( G2 ?+ W2 j! {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.5 _. Q* S0 b' z( }0 g+ {8 f
slide 1020 ; @" r5 Y6 r7 b) f. [% W 5 ~4 L8 o5 ]! ^(1) The closed-loop gain can be modified by changing RS, leaving the closed-loop bandwidth unchanged.) O; n' c( v* ^* Z6 K, t
(2) For a given RF, frequency compensation can be optimized. 0 x/ E! x% t t- p) b+ j' H; t! e(3)Suitable for high frequency applications.3 z2 u g. ?2 N8 T0 {: S* B& g