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slide 1010# ~5 \5 a# m: t# K6 s/ d" r
# s/ z$ X& ^1 V( T8 e1 dFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
2 k% A2 E" }. B, i1 E( X& zThe signal bandwidth is determined by RF and not by the circuit gain.1 Z% v, I* g: a. x L: {
The circuit gain is independently set with RS.6 d* h( x: B) ~. F+ a& M
The signal bandwidth remains stable for all gain settings .2 z3 H; M& h. H0 M! _* ^+ g0 M
Even for unity-gain operation, an RF resistor is required.
9 S) w: U) N9 z: J" \( O; pThe 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.1 O4 {3 i$ k, `9 a* ~6 }; c
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