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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. # a, d: M# Q Z- f8 G, P! w
The signal bandwidth is determined by RF and not by the circuit gain.8 T, z0 o7 W2 |
The circuit gain is independently set with RS.8 m7 `0 }, m% @# t$ M) x
The signal bandwidth remains stable for all gain settings .
. }7 s- O" g L$ g; LEven for unity-gain operation, an RF resistor is required.
8 x$ A! ~% g: u7 b, VThe 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.6 e! R# P: |0 l8 [ M# C6 x4 p
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