GUNN Diodes MCQ’s

This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “GUNN Diodes”.

1. GaAs is used in the fabrication of GUNN diodes because:
a) GaAs is cost effective
b) It less temperature sensitive
c) it has low conduction band electrons
d) less forbidden energy gap

2. In a GaAs n-type specimen, the current generated is constant irrespective of the electric filed applied to the specimen.
a) true
b) false

3. Silicon and germanium are called ___________ semiconductors.
a) direct gap
b) indirect gap
c) band gap
d) indirect band gap

4. When the electric field applied to GaAs specimen is less than the threshold electric field, the current in the material:
a) increases linearly
b) decreases linearly
c) increases exponentially
d) decreases exponentially

5. GaAs is used in fabricating Gunn diode. Gunn diode is:
a) bulk device
b) sliced device
c) made of different type of semiconductor layers
d) none of the mentioned

6. When either a voltage or current is applied to the terminals of bulk solid state compound GaAs, a differential ______ is developed in that bulk device.
a) negative resistance
b) positive resistance
c) negative voltage
d) none of the mentioned

7. When the applied electric field exceeds the threshold value, electrons absorb more energy from the field and become:
a) hot electrons
b) cold electrons
c) emission electrons
d) none of the mentioned

8. The electrodes of a Gunn diode are made of:
a) molybdenum
b) GaAs
c) gold
d) copper

9. The number of modes of operation for n type GaAs is:
a) two
b) three
c) four
d) five

10. The modes of operation of a Gunn diode are illustrated in a plot of voltage applied to the Gunn diode v/s frequency of operation of Gunn diode.
a) true
b) false

11. The frequency of oscillation in Gunn diode is given by:
a) vdom/ Leff
b) Leff/ Vdom
c) Leff/ WVdom
d) none of the mentioned

12. The free electron concentration in N-type GaAs is controlled by:
a) effective doping
b) bias voltage
c) drive current
d) none of the mentioned

13. The mode of operation in which the Gunn diode is not stable is:
a) Gunn oscillation mode
b) limited space charge accumulation mode
c) stable amplification mode
d) bias circuit oscillation mode

14. In Gunn diode oscillator, the Gunn diode is inserted into a waveguide cavity formed by a short circuit termination at one end
a) true
b) false

15. In a Gunn diode oscillator, the electron drift velocity was found to be 107 cm/second and the effective length is 20 microns, then the intrinsic frequency is:
a) 5 GHz
b) 6 GHz
c) 4 GHz
d) 2 GHz

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