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slide 10105 A& C3 Z B/ W/ U2 A' q: g
! o( v/ @0 q7 i: r" wFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. 9 T, D/ p9 L0 ?- k- N2 d
The signal bandwidth is determined by RF and not by the circuit gain.( n, y' [: p) t5 k& B! H
The circuit gain is independently set with RS., F8 A1 {; `4 R; z; `% o+ L9 R1 p
The signal bandwidth remains stable for all gain settings .# N5 x7 m, p; S" c
Even for unity-gain operation, an RF resistor is required.
, {1 }- [- ?* \$ k0 {% s5 O+ {& W8 fThe 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.* d8 G- j5 I C8 D
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