Mirror capacity

In bipolar transistors and field-effect transistors, the phenomenon in which the capacitance between the base and emitter or between the gate and source acts with a multiplier equal to the gain (amplification factor) of the capacitance between the base and collector or between the gate and drain is called the Miller effect, and the input-side capacitance is referred to as the Miller capacitance. If the capacitance between the input and output is C and the amplification factor is A, the Miller capacitance (input capacitance) is expressed by the following formula.

Miller capacitance = C(A+1)

In the Miller effect, a small capacitance between the input and output is amplified into a large Miller capacitance (input capacitance), which affects the frequency characteristics. The name comes from its discoverer and has no relation to “mirror”, despite the similarity in spelling.