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slide 10105 O# h9 T6 l- X% U8 }
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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. . ^- M6 g5 c; E* K" m+ v& Z
The signal bandwidth is determined by RF and not by the circuit gain.# r' D% }$ \, R- ?6 l) _/ }* [- h
The circuit gain is independently set with RS.+ q8 f, ~; e% {6 v! o- c; s. h
The signal bandwidth remains stable for all gain settings .
- ~$ H0 E# R6 R( ~; {0 q0 hEven for unity-gain operation, an RF resistor is required.
9 ~ o* d) c& T* G6 e 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.% i" W) r% ]- ~( r M* E+ h7 j
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