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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.
- q& \* E" m8 i. fThe signal bandwidth is determined by RF and not by the circuit gain.# B% }, ]# e1 J6 V% [- N4 f
The circuit gain is independently set with RS.) r2 k- j9 c- n/ l
The signal bandwidth remains stable for all gain settings .
$ J% {/ N9 b# U8 K y, LEven for unity-gain operation, an RF resistor is required.
7 G q( D7 t6 p/ tThe 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.& }* w V7 T2 {$ T4 l
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