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slide 1010 K4 V, n# `8 L7 e
! v; F4 B9 l6 a: i& m, o {* LFor a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. # H9 I' F/ N- c
The signal bandwidth is determined by RF and not by the circuit gain.% v2 C- k+ |2 E
The circuit gain is independently set with RS.+ d: s& k% g8 y
The signal bandwidth remains stable for all gain settings .
1 r" X, Q0 v# y! A- \6 H) NEven for unity-gain operation, an RF resistor is required.
" i: e6 p: ?% Z/ E0 c, {9 {' WThe 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.; a) b4 I# f0 d+ O% ~3 ^- P& k
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