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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 m* G- c+ y" n( n/ G& @
The signal bandwidth is determined by RF and not by the circuit gain.
. n) [- k4 n, E# H2 I9 aThe circuit gain is independently set with RS.' T: X# I* L8 ?- c R
The signal bandwidth remains stable for all gain settings .
8 ~$ M6 n9 \# C" N7 s* F z$ FEven for unity-gain operation, an RF resistor is required.
2 i( ?# b' W: v4 k: x, cThe 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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