slide 1010 ( k8 u3 W9 u& U! x) c/ e) S0 N" p: ^, p$ p/ t
For a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. 4 |( G ]0 L& C4 X) }: {4 ^8 T' u
The signal bandwidth is determined by RF and not by the circuit gain. ' {8 H5 h5 K' \; J* z: xThe circuit gain is independently set with RS.- O3 I) ~& o: ], K& q1 V
The signal bandwidth remains stable for all gain settings . $ {# I: Q8 x, {7 Y( q8 cEven for unity-gain operation, an RF resistor is required.) b8 B. e" @5 r) x9 U7 i0 ~1 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.8 i2 W0 z" d: e; ^
. N/ N& \! {7 S* w(1) The closed-loop gain can be modified by changing RS, leaving the closed-loop bandwidth unchanged.2 F; X6 T+ u+ _ P# u% P) }
(2) For a given RF, frequency compensation can be optimized. + h! k- Z, n3 U+ b; p# F, t: Q(3)Suitable for high frequency applications. 1 K9 P1 j1 H: B2 `1 c( c