Question 1

When forward biased, the PIN diode acts as a

Accepted Answer

When forward biased, a PIN diode acts as a current-controlled resistance. The level of current flowing through the diode controls its resistance, making it lower as the current increases.

Question 2

The capacitance of a varactor varies

Accepted Answer

The capacitance of a varactor diode varies inversely with the width of its depletion layer because as the depletion layer increases in width, the capacitance decreases, and vice versa. This is due to the fact that capacitance is inversely proportional to the distance between the charges (in this case, the width of the depletion layer).

Question 3

A tuned amplifier contains a 2.2 mH inductor in its tank circuit, along with a varactor with the following ratings: Ct = 80 pF when Vr = 3 Vdc and CR = 3 for V = 3 Vdc to 6 Vdc. What is the resonant frequency of the circuit when VR = 3 Vdc?

Accepted Answer

The resonant frequency $ f_0 $ is calculated using the formula $ f_0 = \frac{1}{2\pi\sqrt{LC}} $. With $ L = 2.2 \, \text{mH} $ and $ C = 80 \, \text{pF} $, the resonant frequency is approximately 379.4 kHz.

Question 4

A tuned amplifier has a 2.2 mH inductor and a varactor in its tank. The varactor has the ratings Ct = 72 pf when Vr = 3 Vdc and a Cr = 2.7 for V = 3 Vdc to 6 Vdc. What is the resonant frequency of the circuit described when VR = 6 Vdc?

Accepted Answer

The answer of A tuned amplifier has a 2.2 mH...

Question 5

The clamping voltage Vc) rating of a transient suppressor indicates

Accepted Answer

The clamping voltage rating of a transient suppressor indicates the maximum voltage across the device at a given value of reverse surge current. This is a critical parameter for ensuring that the suppressor can effectively protect sensitive electronic circuits from voltage spikes.

Question 6

Which of the following are characteristics of an effective surge protection circuit?

Accepted Answer

An effective surge protection circuit should have high power dissipation capability to handle large surges and a rapid turn-on time to quickly respond to voltage spikes.

Question 7

The maximum reverse standoff voltage VRWM) rating of a transient suppressor indicates

Accepted Answer

The maximum reverse standoff voltage (VRWM) rating of a transient suppressor indicates the maximum reverse voltage that can be applied without driving the component into its zener (or avalanche) operating region, ensuring it remains in a non-conducting state under normal operating conditions.

Question 8

A series current regulator is used to

Accepted Answer

A series current regulator maintains a constant current to a load despite variations in input voltage, ensuring the load receives a steady current flow.

Question 9

When reverse biased, the capacitance of a PIN diode can be varied like that of the varactor.

Accepted Answer

In reverse bias, the capacitance of a PIN diode can be varied by changing the reverse bias voltage, similar to how the capacitance of a varactor diode is controlled, making it useful in RF and microwave frequency applications for tuning and switching.

Question 10

The PIN diode actually contains pn junctions).

Accepted Answer

The answer of The PIN diode actually contains pn junctions).
...

Question 11

Forward voltage and current are directly proportional for a tunnel diode that is operated between its peak voltage VP ) and its valley voltage VV ).

Accepted Answer

For a tunnel diode operated between its peak voltage (V_P) and its valley voltage (V_V), the current actually decreases as the voltage increases, which is a characteristic of negative differential resistance, not a direct proportionality.

Question 12

Schottky diodes have extremely low

Accepted Answer

Schottky diodes are known for their low forward voltage drop (VF), which allows for higher efficiency in applications where power conservation is critical. They do not have a reverse recovery time (VRRM is not directly related to their characteristic features), and they typically have low junction capacitance, which allows for fast switching speeds.

Question 13

The tunnel diode is a

Accepted Answer

The tunnel diode is heavily doped, which allows it to operate at very high frequencies, making it suitable for high-frequency communications applications.

Question 14

Constant-current diodes are also known as

Accepted Answer

Constant-current diodes are specifically designed to regulate and maintain a constant current flow, hence they are known as current regulator diodes.

Question 15

The tunnel diode region of operation between VP and VV is called the

Accepted Answer

The tunnel diode region of operation between VP (peak voltage) and VV (valley voltage) is known as the negative resistance region, where an increase in voltage leads to a decrease in current.

Question 16

Constant-current diodes have

Accepted Answer

Constant-current diodes, also known as current-regulating or current-limiting diodes, are designed to maintain a constant current over a wide range of voltage, which is achieved through a high internal impedance. This characteristic allows them to regulate current without significant variation, despite changes in the load or supply voltage.

Question 17

A varactor with a high capacitance ratio CR) rating would be well suited for use in

Accepted Answer

A high capacitance ratio (CR) in a varactor is ideal for coarse-tuning circuits, as it allows for a wider range of frequency adjustment.

Question 18

Back-to-back suppressors contain two components that are connected

Accepted Answer

Back-to-back suppressors are connected cathode-to-cathode to allow bidirectional suppression of voltage spikes.

Question 19

The varactor can be used as a

Accepted Answer

Varactors are designed to act as voltage-controlled capacitors when they are reverse biased, not forward biased or current-controlled.

Question 20

The tunnel diode can be used as the active device in a

Accepted Answer

Tunnel diodes exhibit negative resistance, which makes them suitable for use in oscillators.

Quiz 5: Special Applications Diodes