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slide 1010! v @7 E* \2 l! A' t
5 A3 ^6 G( Q/ y* t. x" S! oFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
# {+ W! F" Q8 \, v) f& L+ W) \The signal bandwidth is determined by RF and not by the circuit gain. c8 G% r/ ~3 ~8 [; f, C4 E" W
The circuit gain is independently set with RS.) p. Z' L: |/ t: n+ N F
The signal bandwidth remains stable for all gain settings .
# E5 y1 l( c& p8 X* Y5 s( AEven for unity-gain operation, an RF resistor is required.( f v% }3 S" `3 \4 a0 g3 }" O1 \
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.! Q, C' S1 g \9 ^! e
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