# Device Modelling and Performance Estimation in VLSI MCQ Quiz – Objective Question with Answer for Device Modelling and Performance Estimation in VLSI

1. MESFETs are _______ modulation devices.

A. channel area
B. channel voltage
C. channel current
D. channel variation

MESFETs are channel area modulation devices and they depend upon the capacitance of the Schottky barrier.

2. Gallium arsenide has _____ regions of operation.

A. two
B. three
C. four
D. five

Gallium arsenide devices have three regions of operation – cutoff, linear, and saturation.

3. Drain to source current is due to

A. flow of majority carriers from drain to source
B. flow of minority carriers from drain to source
C. flow of majority carriers from source to drain
D. flow of majority carriers from drain to source

The current Ids results due to the flow of electrons, the majority carrier from source to drain. Ids can be given as the ratio of charge induced in the channel to electron transit time.

4. Transit time can be given as the ratio of

A. channel length to velocity
B. electron distance to velocity
C. source length to velocity
D. drain length to velocity

The transit time is given as the ratio of channel length to velocity and the carrier velocity can be further given as the product of electric field and electron mobility.

5. The average potential is given as

A. Vgs – Vt
B. 0.5(Vgs – Vt)
C. 0.25(Vgs – Vt)
D. 2(Vgs – Vt)

The average potential difference between the gate and the channel (VgB. owing to the shape of the depletion layer can be given as 0.5(Vgs-Vt).

6. Average electric field is _______ to implant depth.

A. directly proportional
B. indirectly proportional
C. does not depend
D. exponentially dependent

The average electric field is indirectly proportional to implant depth and this electric field can be given as (Vgs-Vt)/a.

7. The range of kp in MESFET is

A. 0.1 to 1 mA/V2
B. 1 to 5 mA/V2
C. 0.1 to 0.5 mA/V2
D. 0 to 1 mA/V2

β is a common parameter used in MESFET and it is denoted by kp. Kp is in the order of 0.1 to 0.5 mA/V2.

8. The hyperbolic tangent function is used to describe the

A. channel conductance
B. channel length
C. channel strength
D. channel depth

The hyperbolic tangent function tanh(aVds) is used to describe the channel conductance at the low drain to source voltage Vds.

9. The magnitude of the depletion region decreases when

A. Vgs decreases
B. Vgs increases
C. Vds increases
D. Vds decreases

When the gate to source voltage Vgs increases, the magnitude of the depletion region beneath the gate decreases.

10. Current saturation occurs when

A. Vgs < Vt
B. Vgs > Vt
C. Vgs > Vds
D. Vgs = Vt