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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 O/ F# V% @/ i/ ~" c" W# I& w
The signal bandwidth is determined by RF and not by the circuit gain.
8 ]2 o) g7 N3 F; a6 x( m' nThe circuit gain is independently set with RS.
5 G1 g$ \8 t- }" mThe signal bandwidth remains stable for all gain settings .
- `& \' m* L: G- e8 eEven for unity-gain operation, an RF resistor is required.* ^8 V- [, [2 l" c/ n
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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