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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.
( B1 P/ p1 V& D+ ?, N1 tThe signal bandwidth is determined by RF and not by the circuit gain.2 m2 k, I0 N; h; P' }$ F. y
The circuit gain is independently set with RS.
c: v+ ~ p9 z% l4 V: ?( }The signal bandwidth remains stable for all gain settings .
+ X( m7 Q8 N; Y9 [! I- k7 |; D( AEven for unity-gain operation, an RF resistor is required.: g2 F# h1 O* N( d/ `
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.
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