# The FET Small-Signal Model MCQ’s

This set of Electronic Devices & Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The FET Small-Signal Model”.

1. For a FET, graph is drawn by taking voltage VGS in X axis and drain current in Y axis, if the value of X changes from 10 to 20 results in change in value of Y axis from 2 to 3. What is the value of trans conductance?
a) 1
b) 2
c) 0.1
d) 0.01

2. The slope obtained in VGS vs ID was 0.002. What is the value ofgm?
a) 1
b) 2
c) 0.002
d) 0

3. What is trans-conductance?
a) Ratio of change in drain current to change in collector current
b) Ratio of change in drain current to change in gate to source voltage
c) Ratio of change in collector current to change in drain current
d) Ratio of change in collector current to change in gate to source voltage

4. Which of the following is an expression for gm0?
a) gm0 = IDSS/Vp
b) gm0 = 2IDSS/|Vp|
c) gm0 = IDSS/5Vp
d) gm0 = IDSS/2Vp

5. Find the value of gm for FET with IDSS=8mA, Vp=4V, VGS=-0.5V?
a) 1mS
b) 2mS
c) 3mS
d) 3.5mS

6. Determine the value of output impedance for JFET, if the value of gm =1mS?
a) 1Kohm
b) 0
c) 100Kohm
d) 5Kohm

7. Find the maximum value of gm for FET with IDSS=10mA, Vp=-2V, VGS=5V?
a) 10mS
b) 20mS
c) 1mS
d) 0

8. A FET has IDSS=4ID and gm0 = 10mS then gm = _________________________
a) 10mS
b) 20mS
c) 5mS
d) 14mS

9. In a small signal equivalent model of an FET, What does gm VGS stand for?
a) A pure resistor
b) Voltage controlled current source
c) Current controlled current source
d) Voltage controlled voltage source

10. Given yfs = 3.6mS and yos = 0.02mS, determine r0?
a) 100Kohm
b) 50Mohm
c) 50Kohm
d) 20Kohm