1.8 MILLER'S THEOREM
Miller’s theorem states that if an impedance is connected between the input and output nodes in an amplifier, having a reference node N, then this impedance can be replaced by two impedances, one connected between the input and the reference node and the other connected between the output and the reference node.
Consider an amplifier in which N is the reference node and 1 and 2 are the input and output nodes. A resistance R′ is connected between nodes 1 and 2, as shown in Fig. 1.48(a).
Let I1 be the current leaving node1.
where AV = V2/V1 is the voltage gain and
Thus, if R′ is removed and a resistance R1 is connected ...