The GATE Grind

GATE 2017 EC – Question 24

Analog Circuits · BJT and MOSFET Amplifiers · 1 mark · Multiple choice

The Miller effect in the context of a Common Emitter amplifier explains

  1. an increase in the low-frequency cutoff frequency
  2. an increase in the high-frequency cutoff frequency
  3. a decrease in the low-frequency cutoff frequency
  4. a decrease in the high-frequency cutoff frequency

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Correct answer: (D) a decrease in the high-frequency cutoff frequency

Explanation

The Miller effect makes the base-collector capacitance look larger at the input by a factor of $(1 + |A_v|)$. This extra capacitance lowers the upper cutoff frequency, so the high-frequency cutoff falls.