PN Junction Devices

Case Based Study -Each case study question will be assigned to a group of 9 students based on nominal roll order. The last batch will be assigned 8 students. 1. A mobile charger adapter fails frequently due to overheating of the rectifier section. Analyze the structure and V–I characteristics of the PN junction diode used in the rectifier circuit. Examine how improper biasing and excessive forward current affect diode operation. Suggest design modifications to improve reliability. (Industry: Samsung Power Systems | Bloom’s Level: L4 – Analyze | CO2) 2. An industrial DC power supply shows excessive ripple in output voltage affecting control circuits. Analyze the working of Half Wave and Full Wave Rectifiers and evaluate the effectiveness of capacitor filters in ripple reduction. Justify which rectifier configuration is suitable for industrial applications. (Industry: L&T Electrical | Bloom’s Level: L5 – Evaluate | CO2) 3. A high-speed switching circuit in an SMPS experiences power loss and signal distortion. Examine diode switching characteristics including storage time and reverse recovery time. Analyze how switching delay impacts efficiency in high-frequency applications. (Industry: Delta Electronics | Bloom’s Level: L4 – Analyze | CO2) 4. A voltage regulator circuit fails to maintain constant output during load variations. Analyze the V–I characteristics of Zener diode and evaluate its performance as a voltage regulator. Suggest suitable design improvements to ensure stable regulation. (Industry: Bosch Automotive Electronics | Bloom’s Level: L5 – Evaluate | CO2) 5. A solar street light system delivers low output power during cloudy conditions. Analyze the working principle and I–V characteristics of Photovoltaic (PV) cells. Evaluate the factors affecting efficiency and suggest engineering improvements. (Industry: Tata Power Solar | Bloom’s Level: L4 – Analyze | CO2) 6. An optical communication system shows reduced sensitivity at the receiver end. Examine the operation of Photodiode under reverse bias condition. Analyze how junction capacitance affects response time and bandwidth. (Industry: BSNL / Optical Networks | Bloom’s Level: L4 – Analyze | CO2)