# 29 Lecture

## Terminal characteristics of the Junction diodes

Junction diodes are a fundamental component of electronic circuits, and they have a variety of applications. One of the key aspects of a junction diode is its terminal characteristics, which refer to the behavior of the diode in response to appl

## Important Mcq's Midterm & Finalterm Prepration Past papers included

What is the typical forward voltage drop for a silicon PN junction diode?

A. 0.3V

B. 0.5V

C. 0.7V

D. 1.0V

What is the depletion region of a PN junction?

A. The region where the mobile charge carriers are depleted

B. The region where the mobile charge carriers are accumulated

C. The region where the doping concentration is highest

D. The region where the doping concentration is lowest

Answer: A. The region where the mobile charge carriers are depleted

What is reverse saturation current?

A. The current that flows in the forward direction when the diode is forward-biased

B. The current that flows in the reverse direction when the diode is forward-biased

C. The current that flows in the forward direction when the diode is reverse-biased

D. The current that flows in the reverse direction when the diode is reverse-biased

Answer: D. The current that flows in the reverse direction when the diode is reverse-biased

What is the breakdown voltage of a PN junction diode?

A. The voltage at which the diode turns on

B. The voltage at which the diode turns off

C. The voltage at which the diode starts to conduct heavily in the forward direction

D. The voltage at which the diode breaks down and allows a large current to flow in the reverse direction

Answer: D. The voltage at which the diode breaks down and allows a large current to flow in the reverse direction

What is the diode equation?

A. An empirical relationship between the current flowing through a PN junction diode and the voltage across it

B. A mathematical relationship between the resistance of a diode and its temperature coefficient

C. A relationship between the doping concentration of a diode and its breakdown voltage

D. A relationship between the size of a diode and its maximum power dissipation

Answer: A. An empirical relationship between the current flowing through a PN junction diode and the voltage across it

What is the typical reverse leakage current of a silicon PN junction diode?

A. Microamperes

B. Milliamperes

C. Amperes

D. The reverse leakage current of a diode is always zero

What is the ideality factor of a PN junction diode?

A. A measure of how closely the behavior of a diode follows the ideal diode equation

B. A measure of the temperature coefficient of a diode

C. A measure of the doping concentration of a diode

D. A measure of the physical size of a diode

Answer: A. A measure of how closely the behavior of a diode follows the ideal diode equation

What happens to the forward current through a diode as the forward voltage is increased?

A. It remains constant

B. It decreases

C. It increases exponentially

D. It increases linearly

What happens to the reverse current through a diode as the reverse voltage is increased?

A. It remains constant

B. It decreases

C. It increases exponentially

D. It increases linearly

What is the typical reverse breakdown voltage for a silicon PN junction diode?

A. 5V

B. 10V

C. 50V

D. 100V

## Subjective Short Notes Midterm & Finalterm Prepration Past papers included

What is a PN junction?

Answer: A PN junction is formed when a P-type semiconductor is joined to an N-type semiconductor.

What is forward biasing of a PN junction?

Answer: Forward biasing of a PN junction is the process of applying a positive voltage to the P-type material and a negative voltage to the N-type material.

What is reverse biasing of a PN junction?

Answer: Reverse biasing of a PN junction is the process of applying a negative voltage to the P-type material and a positive voltage to the N-type material.

What is the forward voltage drop of a PN junction diode?

Answer: The forward voltage drop of a PN junction diode is typically around 0.7V for silicon diodes and 0.3V for germanium diodes.

What is reverse saturation current?

Answer: Reverse saturation current is the small current that flows when a PN junction is reverse-biased.

What is the depletion region of a PN junction?

Answer: The depletion region is the region around the PN junction where the mobile charge carriers have been depleted due to the diffusion of majority carriers.

What is the breakdown voltage of a PN junction diode?

Answer: The breakdown voltage of a PN junction diode is the voltage at which the diode breaks down and allows a large current to flow in the reverse direction.

What is the reverse leakage current of a PN junction diode?

Answer: The reverse leakage current is the small current that flows in the reverse direction even when the diode is reverse-biased.

What is the diode equation?

Answer: The diode equation is an empirical relationship between the current flowing through a PN junction diode and the voltage across it.

What is the ideality factor of a PN junction diode?

Answer: The ideality factor is a measure of how closely the behavior of a PN junction diode follows the ideal diode equation. A value of 1 indicates ideal behavior, while values greater than 1 indicate non-ideal behavior.

### Terminal characteristics of the Junction diodes

Junction diodes are a fundamental component of electronic circuits, and they have a variety of applications. One of the key aspects of a junction diode is its terminal characteristics, which refer to the behavior of the diode in response to applied voltage and current. When a junction diode is forward-biased, it conducts current easily, whereas it behaves as an insulator when it is reverse-biased. This is due to the nature of the PN junction, which is a boundary region between p-type and n-type semiconductor material. When the diode is forward-biased, the voltage applied to the p-type material makes the holes in the material move towards the junction, while the voltage applied to the n-type material makes the electrons in the material move towards the junction. The electrons and holes combine at the junction, allowing current to flow easily through the diode. On the other hand, when the diode is reverse-biased, the voltage applied across the diode creates an electric field that pushes the majority carriers away from the junction, resulting in a region with few carriers that behaves like an insulator. The terminal characteristics of a junction diode can be analyzed through a graphical representation known as the voltage-current (V-I) characteristic curve. This curve plots the current flowing through the diode against the voltage applied across it. The shape of the V-I curve depends on the type of diode, the doping level of the semiconductor material, and the temperature of the diode. For a silicon diode, the V-I characteristic curve is typically characterized by four regions: the forward bias region, the reverse bias region, the breakdown region, and the saturation region. In the forward bias region, the current flowing through the diode increases rapidly with increasing voltage, due to the easy flow of current through the junction. In the reverse bias region, the current flowing through the diode is negligible, as the diode behaves as an insulator. As the reverse bias voltage is increased beyond a certain threshold, the breakdown region is reached, and the current through the diode increases rapidly. In the saturation region, the current through the diode reaches a maximum value and does not increase further with increasing voltage. In addition to the V-I characteristic curve, another important parameter that characterizes a junction diode is the forward voltage drop, which is the voltage required to forward-bias the diode and cause it to conduct current. For a silicon diode, the typical forward voltage drop is around 0.7 volts. The terminal characteristics of a junction diode have important implications for its use in electronic circuits. For example, diodes can be used as rectifiers, which convert AC voltage to DC voltage by allowing current to flow in only one direction. In this application, the forward bias region of the V-I characteristic curve is used, while the reverse bias region is avoided. Diodes can also be used as voltage regulators, where they maintain a constant voltage across a load by operating in the breakdown region of the V-I characteristic curve. In conclusion, the terminal characteristics of a junction diode are an important aspect of its behavior and have important implications for its use in electronic circuits. By understanding the V-I characteristic curve and the forward voltage drop of a diode, engineers can design circuits that make the most of this fundamental component.