Deck 3: Special-Purpose Diodes

Question 1

Figure 4
Refer to Figure 4. The symbol for a varactor diode is voltage across the load is

A)(a)
B)(b)
C)(c)
D)(d)

Answer 1

B

Question 2

Figure 2
Refer to Figure 2. The maximum negative output voltage is

A)-8.0 V
B)-4.7 V
C)-5.4 V
D)-4.0 V

Answer 2

D

Question 3

Figure 2
Refer to Figure 2. This circuit is a

A)voltage multiplier
B)clamper
C)limiter
D)regulator

Answer 3

C

Question 4

A Schottky diode is primarily used as a

A)regulator
B)fast switching diode
C)low- frequency rectifier
D)variable capacitor

Question 5

When a zener diode is forward biased, the voltage drop will be approximately

A)0.7 V
B)VZ + 0.7 V
C)VZ - 0.7 V
D)VZ

Question 6

Reverse leakage current for a zener diode is specified

A)at a voltage that is less than the knee voltage
B)in reverse breakdown
C)at the knee voltage
D)none of the above

Question 7

An OLED produces light by a process called

A)avalanche light emission
B)organic light emission
C)photonic light emission
D)electrophosphorescence

Question 8

An application for an infrared diode is

A)traffic lights
B)in seven- segment displays
C)in a remote control for TV
D)all of the above

Question 9

In maximum power point tracking, maximum power is obtained by adjusting the

A)internal resistance
B)temperature
C)load resistance
D)bias voltage

Question 10

A photodiode can be controlled by light intensity to form a variable

A)capacitive device
B)resistance device
C)light source
D)all of the above

Question 11

Assume the frequency of a resonant circuit is varied with a varactor that has a minimum capacitance of 5 pF and a maximum capacitance of 50 pF. The ratio of highest to lowest frequency the circuit can tune is

A)greater than 10
B)10
C)less than 10

Question 12

Figure 1 V_Z = 5.1 V at I_Z = 49 mA, I_ZK = 1 mA, and Z_Z = 7 ▲ over the range of current values.
Refer to Figure 1. Assume a 200 ▲ load resistor is connected across the output and the zener current is 49 mA. What is VIN?

A)14.9 V
B)24.7 V
C)20.0 V
D)12.2 V

Question 13

Compared to incandescent lamps, LEDs are

A)more efficient
B)have a longer lifetime
C)both A and B
D)none of the above

Question 14

Figure 1 V_Z = 5.1 V at I_Z = 49 mA, I_ZK = 1 mA, and Z_Z = 7 ▲ over the range of current values.
Refer to Figure 1. What setting of VIN will give an output closest to 5.1 V?

A)9.8 V
B)14.9 V
C)5.3 V
D)6.1 V

Question 15

In an IC regulator, an internal zener diode is used as a

A)reference
B)control element
C)feedback element
D)all of the above

Question 16

Figure 6
Refer to Figure 6. This is the schematic symbol for a

A)current regulator diode
B)Schottky diode
C)step- recovery diode
D)tunnel diode

Question 17

A reverse- biased PIN diode acts like a

A)constant capacitance
B)variable resistance
C)constant current source
D)constant voltage source

Question 18

Figure 8
Refer to Figure 8. Assume a 150 ▲ resistor is put in parallel with RL. The new zener current will be

A)48 mA
B)100 mA
C)0 mA
D)3 mA

Question 19

Figure 4
Refer to Figure 4. The symbol for an LED is output voltage will be

A)(a)
B)(b)
C)(c)
D)(d)

Question 20

Figure 8
Refer to Figure 8. If the circuit is operating normally, the current in the zener diode is

A)30 mA
B)15 mA
C)45 mA
D)0 mA

Question 21

Power dissipation in a zener diode is the product of zener voltage and the current in the zener.

Question 22

Typically, the VF for an LED is between

A)1.2 V and 3.2 V
B)3.2 V and 6.5 V
C)0 V and 0.6 V
D)0.6 V and 1.2 V

Question 23

The crystalline solar cell converts sunlight to electricity using the photovoltaic effect.

Question 24

Zener impedance is defined as

A)VZK/IZK
B)VZM/IZM
C)OVZ/OIZ
D)VZ/IZ

Question 25

Figure 7
Refer to Figure 7. The curve is for a

A)Schottky diode
B)tunnel diode
C)current regulator diode
D)PIN diode

Question 26

Figure 2
Refer to Figure 2. The maximum positive output voltage is

A)+4.0 V
B)+4.7 V
C)+8.0 V
D)+5.4 V

Question 27

Figure 8
Refer Figure 8. If the zener diode is open, the output voltage will be

A)7.0 V
B)5.0 V
C)0 V
D)9.0 V

Question 28

Figure 2
Refer to Figure 2. Assume the top diode is reversed. The circuit will

A)clip negative peaks below -8.0 V
B)clip positive peaks above +8.0 V
C)both A and B
D)none of the above

Question 29

LED color is determined primarily by the

A)particular semiconductor and impurities added
B)color of the plastic covering
C)size of the diode
D)amount of forward current

Question 30

Photodiodes and varactor diodes are normally operated with reverse- bias.

Question 31

A diode with a negative resistance characteristic is a varactor diode.

Question 32

In a silicon solar cell, sunlight

A)creates electron- hole pairs
B)increases the resistance of the cell
C)produces a useable voltage of 5- 6 V across the cell
D)all of the above

Question 33

A zener diode is also called a tuning diode.

Question 34

Figure 1 V_Z = 5.1 V at I_Z = 49 mA, I_ZK = 1 mA, and Z_Z = 7 ▲ over the range of current values.
Refer to Figure 1. What is the output voltage if IZ = 20 mA?

A)4.9 V
B)5.1 V
C)4.8 V
D)5.0 V

Question 35

The forward voltage across an LED is considerably less than for a silicon diode.

Question 36

Figure 5 A solar panel
Refer to Figure 5. The cells are connected in series to increase

A)resistance
B)both current and voltage
C)current
D)voltage

Question 37

Different color LEDs require different forward voltages to operate.

Question 38

A 1N4742A has a maximum power rating of 1.0 W at 50 °C. The derating factor is 9.67 mW/°C. If it is operated at 70 °C, the maximum power is

A)0.8 W
B)1.1 W
C)0.9 W
D)1.2 W

Question 39

An application for tunnel diodes is

A)as rectifiers
B)in high- frequency oscillators
C)in switching circuits
D)as variable capacitors

Question 40

Figure 3 Bias curve for a typical varactor diode
Refer to Fig 3. For the varactor diode shown, the CR between 0.5 V and 10 V is approximately

A)18
B)11
C)5.9
D)1.5