Deck 5: Microwave Devices and Their Operation: Gunn Diodes, Impatt Diodes, Klystron Tubes

Question 1

The frequency of oscillation in Gunn diode is given by:

A)vdom/ leff
B)leff/ vdom
C)leff/ wvdom
D)none of the mentioned

Answer 1

vdom/ leff

Question 2

In Gunn diode oscillator, the Gunn diode is inserted into a waveguide cavity formed by a short circuit termination at one end

Answer 2

True

Question 3

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

Answer 3

5 ghz

Question 4

The material used to fabricate IMPATT diodes is GaAs since they have the highest efficiency in all aspects.

Question 5

3 IMPATT DIODES, SCHOTTKY BARRIER DIODES, PIN DIODES

A)avalanche multiplication
B)break down of depletion region
C)high reverse saturation current
D)none of the mentioned

Question 6

To prevent an IMPATT diode from burning, a constant bias source is used to maintain __________  at safe limit.

A)average current
B)average voltage
C)average bias voltage
D)average resistance

Question 7

The number of semiconductor layers in IMPATT diode is:

A)two
B)three
C)four
D)none of the mentioned

Question 8

The resonant frequency of an IMPATT diode is given by:

A)vd/2L
B)vd/l
C)vd/2?l
D)vdd/4?l

Question 9

If the length of the intrinsic region in IMPATT diode is 2 µm and the carrier drift velocity are 107 cm/s, then the nominal frequency of the diode is:

A)12 ghz
B)25 ghz
C)30 ghz
D)24 ghz

Question 10

IMPATT diodes employ impact ionization technique which is a noisy mechanism of generating charge carriers.

Question 11

An essential requirement for the BARITT diode is that the intermediate drift region be completely filled to cause the punch through to occur.

Question 12

If the RMS peak current in an IMPATT diode is 700 mA and if DC input power is 6 watt, with the load resistance being equal to

A)10.1 %
B)10.21 %
C)12 %
D)15.2 %

Question 13

If the critical field in a Gunn diode oscillator is 3.2 KV/cm and effective length is 20 microns, then the critical voltage is:

A)3.2 v
B)6.4 v
C)2.4 v
D)6.5 v

Question 14

The production of power at higher frequencies is much simpler than production of power at low frequencies.

Question 15

Microwave tubes are power sources themselves at higher frequencies and can be used independently without any other devices.

Question 16

The klystron tube used in a klystron amplifier is a __________type beam amplifier.

A)linear beam
B)crossed field
C)parallel field
D)none of the mentioned

Question 17

In crossed field tubes, the electron beam traverses the length of the tube and is parallel to the electric field.

Question 18

__________    is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity.

A)backward wave oscillator
B)reflex klystron
C)travelling wave tube
D)magnetrons

Question 19

A major disadvantage of klystron amplifier is:

A)low power gain
B)low bandwidth
C)high source power
D)design complexity

Question 20

In a __________oscillator, the RF wave travels along the helix from the collector towards the electron gun.

A)interaction oscillator
B)backward wave oscillator
C)magnetrons
D)none o the mentioned

Question 21

Magnetrons are microwave devices that offer very high efficiencies of about 80%.

Question 22

Klystron amplifiers have high noise output as compared to crossed field amplifiers.

Question 23

__________      is a microwave device in which the frequency of operation is determined by the biasing field strength.

A)vtm
B)gyratron
C)helix bwo
D)none of the mentioned