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slide 10103 E7 G5 v2 v" e& W3 e+ r
2 z1 j+ I) o8 N4 O* {6 TFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF.
. M' \# w' s. t& | i5 g2 CThe signal bandwidth is determined by RF and not by the circuit gain.- \* V! `2 |+ m" I' e3 Z* q; x
The circuit gain is independently set with RS.8 W' N9 c' q$ L, D2 m# c1 }
The signal bandwidth remains stable for all gain settings .
2 \$ ~ I% H* S' x, v! [3 b$ JEven for unity-gain operation, an RF resistor is required./ h9 \ B+ i7 R0 T4 z- P
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.9 F% C8 I9 X" J. B' d6 K+ s5 B8 z. s
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