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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. : f+ ~) F/ a8 q( C1 S/ l& ~
The signal bandwidth is determined by RF and not by the circuit gain.1 @& F9 o5 O9 q% [
The circuit gain is independently set with RS.2 g/ B0 F% h; [; g4 E( Q
The signal bandwidth remains stable for all gain settings . ) J$ P# t1 B1 [3 N1 t1 C% j* Q1 {Even for unity-gain operation, an RF resistor is required.: K' X1 _# U2 \
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.( n5 G6 h% [4 x: X
" [# a+ _% S0 ^2 J/ d(1) The closed-loop gain can be modified by changing RS, leaving the closed-loop bandwidth unchanged. 4 d- U( B% i6 N1 W(2) For a given RF, frequency compensation can be optimized.+ c9 [* I# B7 v& C; r
(3)Suitable for high frequency applications.+ l. y* \7 x' {: c: j T