21. Threshold voltage is ________ on implant depth.
A. proportionally dependent
B. inversely proportionally dependent
C. exponentially dependent
D. logarithmically dependent
Answer: C
The threshold voltage is exponentially dependent on implant depth and there is a need for proper control of channel thickness.
22. The drain current is independent of
A. Vgs
B. Vds
C. Vt
D. Vs
Answer: A
The drain current saturates at the same drain to source voltage Vds and is independent of the gate to source voltage Vgs.
23. Impurity concentration should be
A. greater than 20%
B. lesser than 20%
C. greater than 10%
D. lesser than 10%
Answer: B
The channel thickness should be controlled within 20 Armstrong and the change in impurity concentration should be less than 20%.
24. Threshold voltage is independent of pinch-off voltage.
A. true
B. false
Answer: B
The threshold voltage is dependent upon pinch-off voltage Vpo and barrier potential and this is given as the difference between the two.
25. Pinch-off voltage is ______ to channel concentration density.
A. directly related
B. inversely related
C. exponentially related
D. is not related
Answer: A
Pinch-off voltage is directly related to the effective channel concentration density Nd.
26. Gain of MESFET is _______ to transconductance.
A. directly proportional
B. indirectly proportional
C. exponentially dependent
D. does not depend on
Answer: A
The gain of the MESFET is directly dependent on the transconductance and output conductance of the device.
27. Transconductance gives the relationship of
A. Ids and Vds
B. Vds and Vgs
C. Ids and Vgs
D. Ids and d
Answer: C
Transconductance describes the relationship between the output current Ids and the input control voltage Vgs.
28. Output conductance gives the slope of linear characteristics.
A. true
B. false
Answer: B
Output conductance is also used to measure the gain of MESFET and it gives the slope of output characteristics.
29. The transconductance value in cut off region is
A. Vds
B. 1
C. cannot be determined
D. 0
Answer: D
The transconductance value for the cut-off region is 0 and it is the relationship between Ids and Vgs.
30. GaAs device has
A. high bandwidth
B. high transconductance
C. low gate capacitance
D. all of the mentioned
Answer: D
GaAs devices have high transconductance, very low gate capacitance, high gain, and high bandwidth.
