The GATE Grind

GATE 2025 EE – Question 16

Analog and Digital Electronics · Amplifiers: biasing, equivalent circuit and frequency response · 1 mark · Multiple choice

Which one of the following statements is true about the small signal voltage gain of a MOSFET based single stage amplifier?

  1. Common source and common gate amplifiers are both inverting amplifiers
  2. Common source and common gate amplifiers are both non-inverting amplifiers
  3. Common source amplifier is inverting and common gate amplifier is non-inverting
  4. Common source amplifier is non-inverting and common gate amplifier is inverting

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) Common source amplifier is inverting and common gate amplifier is non-inverting

Explanation

In a common-source stage the output is at the drain and the input at the gate, giving a gain of $-g_mR_D$ (inverting). In a common-gate stage the input is at the source, and the gain is $+g_mR_D$ (non-inverting).