Chapter: Electronic Circuits : Feed Back Amplifiers
Principles of Negative Current Feedback
Principles of Negative Current Feedback
In this method, a fraction of output current is
feedback to the input of the amplifier. In other words, the feedback current
(If) is proportional to the output current (Iout) of the amplifier.
Fig. 1.7 shows the principles of negative current feedback. This circuit is
called current-shunt feedback circuit. A feedback resistor Rf is connected
between input and output of the amplifier. This amplifier has a current gain of
Ai without feedback. It means that a current I1 at the
input terminals of the amplifier will appear as Ai I1 in
the output circuit i.e., Iout = Ai I1.
Now a fraction mi of this output
current is fedback to the input through Rf. The fact that arrowhead shows the
feed current being fed forward is because it is negative feedback.
Note that negative current feedback reduces the
input current to the amplifier and hence its current gain.
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