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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.
7 ]( _- Y& T9 ~. f- h$ tThe signal bandwidth is determined by RF and not by the circuit gain./ q% r y0 \( s, z+ V: C. Q& r# n
The circuit gain is independently set with RS.
4 X* i! M* \2 a6 HThe signal bandwidth remains stable for all gain settings .: m0 f+ X3 r ]
Even for unity-gain operation, an RF resistor is required.5 p {9 V0 K& q, N1 b, I
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.- `% y$ [8 I1 B4 T
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