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slide 1010
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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.
. q! m# f" t! e; B# j$ n$ @1 q# D. iThe signal bandwidth is determined by RF and not by the circuit gain.* ~' X% x, X, Q4 [2 C
The circuit gain is independently set with RS.2 E( w9 L+ P" q [, M5 O# |. O$ a; F
The signal bandwidth remains stable for all gain settings .) N& N2 k( N4 }% h
Even for unity-gain operation, an RF resistor is required.
" a- V2 \ k0 P H' H$ I6 oThe 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.8 \ x6 V9 f z6 _! J
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