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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. 2 l( V3 v3 M1 r. ?3 l
The signal bandwidth is determined by RF and not by the circuit gain.
' M$ W& K, G. Q& R3 W8 ~The circuit gain is independently set with RS.$ l( v7 w. Y0 s6 O
The signal bandwidth remains stable for all gain settings .
7 M3 v2 `* t1 }9 k {% kEven for unity-gain operation, an RF resistor is required.
$ L* k& r# b8 E" |, Q' T \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.
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