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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. 1 {$ h0 P! n, s$ C. O8 `* K
The signal bandwidth is determined by RF and not by the circuit gain.4 Y# k( p" v# g4 V) w3 O8 J/ L
The circuit gain is independently set with RS.* `- P7 D" D8 L
The signal bandwidth remains stable for all gain settings .
- c E8 Z4 A z2 G) T5 V2 x! N% KEven for unity-gain operation, an RF resistor is required.
7 @+ c }/ Q6 I3 }# v7 w' L4 }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.* d o: L/ E, Q- Z/ b0 g, z5 z
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