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/ v8 g* Q! T+ R( p) K! hFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
: ^1 K9 ?$ y* I5 ?+ M6 ~ M9 O {The signal bandwidth is determined by RF and not by the circuit gain.1 J k, B1 x k' i1 o
The circuit gain is independently set with RS.; [' E. `9 a% X
The signal bandwidth remains stable for all gain settings .% [8 C- }' U: B2 _( m# ~
Even for unity-gain operation, an RF resistor is required.
* T: |5 {+ M% s2 o9 y; L8 }" ZThe 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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