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slide 10100 E, N( h3 F& S- R+ Z: g
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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. : @, o! j/ k# h; H" ~; k; d
The signal bandwidth is determined by RF and not by the circuit gain.# k" }0 q! N6 B) d" z+ d5 M6 f" W" S% j
The circuit gain is independently set with RS.( V4 E5 ~: `+ q( B
The signal bandwidth remains stable for all gain settings .
# s% N% j4 `( s$ O MEven for unity-gain operation, an RF resistor is required.
1 G! y1 T( V0 g$ I+ v0 LThe 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.) T8 S+ B* H0 N8 r
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