2 O# c- p }/ C' ~For a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. ! c2 Q4 W. t6 P6 s
The signal bandwidth is determined by RF and not by the circuit gain. " f# e! [8 J4 vThe circuit gain is independently set with RS.) n* _) H! ^! C. f, m
The signal bandwidth remains stable for all gain settings . , y* u% @- f' |Even for unity-gain operation, an RF resistor is required. 9 C$ Q! W" P4 M: ~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./ X% G% k' d1 y
slide 1020 . z+ v. u: X4 A2 v" X, ` ) A$ c+ m' }# p1 W. H% s* h, P(1) The closed-loop gain can be modified by changing RS, leaving the closed-loop bandwidth unchanged.% z& { U; Q) `$ u; B; D
(2) For a given RF, frequency compensation can be optimized. 7 c6 ^" y @+ e(3)Suitable for high frequency applications. , v: } H1 G+ ]' {8 ]8 b