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slide 10105 f3 ^6 ^$ o9 w
, y- p; z4 q9 G9 M$ p7 wFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. ; L' }9 Y l2 y% ?, t, I
The signal bandwidth is determined by RF and not by the circuit gain.1 E0 Y2 V M! |! W, u, m# {
The circuit gain is independently set with RS.
; [, f& D+ e. Z( m6 ]/ h% cThe signal bandwidth remains stable for all gain settings .
6 L1 v: [4 q3 K8 \( @' A" Y+ }. ]Even for unity-gain operation, an RF resistor is required.
# ^# T( A& \0 c+ a- }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.& A2 Z9 G I( h" _
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