slide 1010 f0 W5 S7 l* K' Z% N2 K8 Z* L$ I: V8 ]- A
For a CFB amplifier the open-loop gain is ZT and its feedback factor is 1/RF, making the loop-gain TCFB = ZT/RF. ; ?% x C" z9 L/ T s: D9 F
The signal bandwidth is determined by RF and not by the circuit gain. ; Q( P) P1 n {5 P5 UThe circuit gain is independently set with RS.% S! ^$ H& x5 r3 A! d
The signal bandwidth remains stable for all gain settings .0 o8 W7 D- [$ {9 E; c9 u
Even for unity-gain operation, an RF resistor is required.9 m. P0 `8 s/ @/ `
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. 3 @; g5 B7 q5 d4 F3 r7 E
slide 1020 2 d) S- x; I" I 6 n. z, r( {* x(1) The closed-loop gain can be modified by changing RS, leaving the closed-loop bandwidth unchanged.: i O: \5 S7 p
(2) For a given RF, frequency compensation can be optimized.! ]; E$ `( T+ I* \, q
(3)Suitable for high frequency applications." e: J* _# {" u1 ^9 S+ m$ H