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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. / d: {# n; |8 D% O2 Z( d. D( wThe signal bandwidth is determined by RF and not by the circuit gain. : S: G& J- M8 m; ]+ z$ lThe circuit gain is independently set with RS.' X2 @& c, X8 G8 ]: u" P
The signal bandwidth remains stable for all gain settings . + H8 [! n E# L- \Even for unity-gain operation, an RF resistor is required. , {0 |# t; T( @5 b4 Y& A5 J; kThe 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. 7 T" l$ I5 y/ L k/ o
e2 m5 y+ W/ V$ V4 F5 A(1) The closed-loop gain can be modified by changing RS, leaving the closed-loop bandwidth unchanged.( P4 l: {% X, X6 I+ s
(2) For a given RF, frequency compensation can be optimized., J( ~1 I! P4 `2 }, [! N' G1 L4 c
(3)Suitable for high frequency applications.2 p: A, k* `; ]) o8 t- K9 S