MOS Field Effect Transistors (MOSFETs) topics include: The basics of MOSFET, device structure, physical and small signal operation of MOSFET, basics of MOSFET configurations and circuit biasing, body effect and discrete MOSFET circuits. Metal-oxide-semiconductor field-effect transistors (MOSFETs) are electronic devices that are used to control or amplify voltages in circuits. They are the most common type of transistor today.  MOSFETs are typically three-terminal devices with gate (G), drain (D), and source (S) terminals. They are voltage-controlled devices that use an insulated gate to... Show more

MOS Field Effect Transistors (MOSFETs) topics include: The basics of MOSFET, device structure, physical and small signal operation of MOSFET, basics of MOSFET configurations and circuit biasing, body effect and discrete MOSFET circuits.

Metal-oxide-semiconductor field-effect transistors (MOSFETs) are electronic devices that are used to control or amplify voltages in circuits. They are the most common type of transistor today. 

MOSFETs are typically three-terminal devices with gate (G), drain (D), and source (S) terminals. They are voltage-controlled devices that use an insulated gate to determine the conductivity of the device. The amount of voltage applied to the gate terminal controls the conductivity, or how much electricity can flow, between the source and drain terminals. 

MOSFETs are made up of three layers:
Silicon semiconductor
Silicon oxide insulator
Catalytic metal 
The catalytic metal is usually palladium, platinum, iridium, or rhodium, and is also called the gate. 

MOSFETs have many properties, including:
High input impedance
Small reverse transfer capacitance
Wide safe operating region
Low gate power consumption
Easy driving 

MOSFETs are used in many applications, including:
Boost converters
Switching transistors
Knowing the current value and voltage values 

Related Test: Electronic Devices and Circuits Practice Test: Transistor Characteristics

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Electronic Devices and Circuits Practice Test: MOS Field Effect Transistors (MOSFETs)

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25 Questions

1. Which of the following is true for the saturation region?

VSD <| VOV|VDG < |Vtp|VSD ≤| VOV|VDG ≤ |Vtp|

2. Which of the following is the fastest switching device?

MOSFETJEFTBJTTriode

3. Consider the amplifier below for the case V_DD = 5 V, R_D = 24 kΩ, (W/L) = 1 mA/V², and V_t = 1 V. For the input signal of 1.5V what is the value of the gain value obtained?

-12.64 V/V-12.84 V/V-12.44 V/V-12.24 V/V

4. As the voltage on the drain is increased, a value is reached at which the pn junction between the drain region and substrate suffers avalanche breakdown known as

Weak stormWeak avalanchePunch-throughStrong avalanche

5. An n-channel MOSFET operating with V_OV=0.5V exhibits a linear resistance = 1 kΩ when V_DS is very small. What is the value of the device transconductance parameter k_n?

0.2 A/V22 mA/V220 mA/V22 A/V2

6. The circuit below is the characterization for the amplifier as a functional block. Which is true for the value of A_vo for common source (Represented by A₁) and common source with a source resistance (represented by A₂).

|A1| < |A2|A1 < A2A1 = A2A1 > 2

7. For each of the circuits shown find the labeled voltages. For all transistors, k_n(W/L) = 1 mA/V2, V_t = 2V, and λ = 0. Find V₁ and V₂

2V and 4V-2V and -4V-2V and 4V2V and -4V

8. In the saturation region of the MOSFET the saturation current is?

Independent of the voltage difference between the source and the drainDepends directly on the voltage difference between the source and the drainDepends directly on the overdriving voltageDepends directly on the voltage supplied to the gate terminal

9. With the potential difference between the source and the drain kept small (V_DS is small), the MOSFET behaves as a resistance whose value varies __________ with the overdrive voltage

LogarithmicallyExponentiallyLinearlyInversely

10. For each of the circuits shown find the labeled voltages. For all transistors, k_n(W/L) = 1 mA/V2, V_t = 2V, and λ = 0. Find V₄ and V₅

4V and 5V respectively-4V and -5V respectively-4V and 5V respectively4V and -5V respectively

11. The PMOS transistor in the circuit shown has V_t = −0.7 V, μ_pC_ox = 60 μA/V², L = 0.8 μm, and λ = 0. Find the value of R in order to establish a drain current of 0.115 mA and a voltage V_D of 3.5 V.

50 kΩ37.5 kΩ25 kΩ12.5 KΩ

12. The MOSFET circuit below has V_t = 1V, k_nW/L = 0.8 mA/V² and V_A = 40V. If terminal Y is grounded find the voltage gain from X to Z with Z open-circuit.

0.99 V/VNone of these0.66 V/V0.33 V/V

13. The MOSFET transconductance parameter is the product of

Inverse of Process transconductance and inverse of aspect ratioInverse of Process transconductance and aspect ratioProcess transconductance and inverse of aspect ratioProcess transconductance and aspect ratio

14. For a 0.8-μm CMOS fabrication process: V_tn= 0.8 V, V_tp = −0.9 V, μ_nC_ox = 90 μA/V², μ_pC_ox = 30 μA/V², Cox = 1.9 fF/μm2, V_A (n-channel devices) = 8L (μm), and |V_A| (p-channel devices) = 12L (μm). Find the small-signal model parameters (g_m, r_o and g_mb) for a PMOS transistor having W/L = 20 μm/2 μm and operating at I_D = 100 μA and |V_SB| = 1V.

gm= 0.24mA/V, ro=240 kΩ, gmb = 0.048 mA/Vgm= 0.24mA/V, ro= 240 kΩ, gmb = 0.024 mA/Vgm= 0.24mA/V, ro= 120 kΩ, gmb = 0.048 mA/Vgm= 0.12mA/V, ro= 240 kΩ, gmb = 0.048 mA/V

15. A depletion type N channel MOSFEt with k_nW/L = 2 mA/V² and V_t = 3V has its source and gate grounded. For V_d = 0.1V and neglecting channel length modulating effect. Find drain current.

0.89 mA0.3 mA1.18 mA0.59 mA

16. At channel pinch off

The width of the induced channel becomes zero and the current saturatesThe width of the induced channel becomes non linearwidth becomes 1/e times the maximum possible widthThe width of the induced channel becomes very large (resulting in very large resistance and very low, practically zero, current)

17. The MOSFET in the following circuit is in which configuration?

Common Gate (CG)None of theseCommon Source (CS)Common Drain (CD)

18. If in a particular application V_gs is 10 mV, find the minimum overdrive voltage at which the transistor should be operated so that the second-harmonic distortion is kept to less than 1%.

0.75V0.25V0.5V1V

19. For each of the circuits shown find the labeled voltages. For all transistors, k_n(W/L) = 1 mA/V2, V_t = 2V, and λ = 0. Find V₃

4.41V1.41V2.41V3.41V

20. Determine the conditions in which the MOSFET is operating in the saturation region.
i. V_GD > V_t (Threshold voltage)
ii. V_DS > V_OV
iii. I_D ∝ (V_OV)²

i and iii are correcti and ii are correcti, ii, and iii are correctii and iii are correct

21. In which of the following configuration is the input resistance (R_i) not equal to zero ideally?

Common source configurationSource follower configurationCommon gate configurationCommon source configuration with source resistance

22. The MOSFET shown has Vt = 1V, k_n = 100µA/V² and λ = 0. Find the required values of W/L and of R so that when v_I = V_DD = +5 V, r_DS = 50 Ω, and V_O = 50 mV.

W/L = 25 and R = 9.90 kΩW/L = 25 and R = 4.95 kΩW/L = 50 and R = 9.90 kΩW/L = 50 and R = 4.95 kΩ

23. The saturation current of the MOSFET is the value of the current when

The voltage between the drain and drain becomes equal to the threshold voltageThe voltage between the drain and drain becomes equal to the overdrive voltageThe voltage between the drain and drain becomes equal to the voltage applied to the gateThe voltage between the drain and drain becomes equal to difference the overdrive voltage and the threshold voltage

24. Bias point is also referred by the name

All of the mentionedQuiescent PointDC Operating PointNone of these

25. The current i_D is?

Depends inversely on VOV in the triode regionDepends linearly on VOV in the saturation regionNone of theseDepends on the square of VOV in the saturation region