A. low electric field
B. high electric field
C. low magnetic field
D. high magnetic field
Answer: B
The saturation of drain current with an increasing drain to source voltage is caused by velocity saturation which occurs in a high electric field in the channel.
12. Knee voltage is the boundary between
A. active region and saturation region
B. linear and non-linear region
C. linear and saturation region
D. linear and cutoff region
Answer: C
The boundary between the linear and saturation regions defined by Vds=Vgs-Vt is referred to as the ‘knee voltage’.
13. Depletion mode MESFET operates as
A. reverse biased
B. forward biased
C. both reverse and forward biased
D. none of the mentioned
Answer: A
Depletion mode MESFET operates as reverse biased (Vt is lesser than Vgs) and enhancement mode MESFET operates as forward biased.
14. Pinch-off voltage is equal to
A. built-in potential
B. applied voltage
C. sum of built-in potential and applied voltage
D. difference between built-in potential and applied voltage
Answer: C
Pinch-off voltage is the total voltage, both built-in potential and applied voltage necessary to completely deplete the channel of mobile charge carriers.
15. Pinch-off voltage is a function of
A. channel depth
B. channel thickness
C. channel length
D. channel density
Answer: B
Pinch-off voltage is a function of both channel thickness ‘a’ and concentration density Nd and it is always positive.
16. The threshold voltage is sensitive to
A. channel length
B. channel depth
C. doping density
D. doping of the channel layer
Answer: D
The threshold voltage Vt is very sensitive to both the channel thickness ‘a’ and the doping of the channel layer.
17. The dynamic switching energy must exceed the capacitive load.
A. true
B. false
Answer: A
In logic structure, the dynamic switching energy must exceed the energy stored in the capacitive load.
18. To keep dynamic switching energy small
A. logic voltage swing must be large
B. logic current swing must be large
C. logic voltage swing must be small
D. logic current swing must be small
Answer: C
To keep dynamic switching energy small, the logic voltage swing must be kept small. This requires proper control over threshold voltages.
19. Standard deviation of threshold voltage should be ______ of logic voltage swing.
A. less than 5%
B. more than 5%
C. less than 10%
D. more than 10%
Answer: A
To achieve proper control over the threshold voltage, the standard deviation of the threshold voltage should be maintained at less than 5% of the logic voltage swing.
20. In D-MESFET, the voltage swing is less than 1V.
A. true
B. false
Answer: B
In D-MESFET, the logic voltage swing can be larger than 1V which means tolerance to higher threshold voltage variation can be accommodated.
