The GATE Grind

GATE 2023 EC – Question 21

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

In the circuit shown below, $V_1$ and $V_2$ are bias voltages. Based on input and output impedances, the circuit behaves as a

Diagram for GATE 2023 EC question 21
  1. voltage controlled voltage source.
  2. voltage controlled current source.
  3. current controlled voltage source.
  4. current controlled current source.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (B) voltage controlled current source.

Explanation

The input voltage drives the source of the upper-gate-biased transistor through a resistor, so the input current is set by $v_{in}/(R_1+1/g_m)$: the input side is a voltage-driven, finite-impedance port. The output is taken at the drain of a common-gate stage, which has a very high output impedance and delivers a current proportional to that input current. A voltage-driven input and a high-impedance current output make it a voltage controlled current source.