ece-1109 ECE-1109 Introduction to ECE
Topic 1: Semiconductor Physics and PN Junction Diode
This topic covers the fundamental physics of semiconductors, the formation of the PN junction, and basic diode operations.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Definitions & Basic Concepts | Justify the statement: βn-type or p-type semiconductor is electrically neutralβ. | 2022 |
| What is electronic band structure? Using energy band structure explain conductors, semiconductors, and insulators. | 2024 | |
| Briefly explain the formation of energy band in a solid. Classify the solids according to this band structure. | 2023 | |
| What is meant by intrinsic and extrinsic semiconductor? Illustrate the variation of carrier concentration of a semiconductor with the change in temperature. | 2023 | |
| Why is silicon preferred to Germanium in manufacturing semiconductor devices? | 2023 | |
| PN Junction Theory | Explain the formation of depletion layer in a p-n junction. How does the width of this layer change with doping level? | 2022 |
| With the help of suitable diagram, illustrate the current components in a p-n diode. | 2022 | |
| When a p-n junction is at equilibrium, there is a contact potential. Explain how the contact potential is needed to maintain the equilibrium condition. What is the origin of the contact potential? | 2024 | |
| Draw a schematic diagram showing the energy band structure of an open circuited p-n junction. Explain how the carrier and current flow is affected by a forward bias voltage? | 2022, 2024 | |
| Diode Characteristics | Explain the operation of a semiconductor diode for the given conditions: (i) No bias, (ii) forward bias, and (iii) reverse bias. Also, draw the characteristics curve of a silicon diode. | 2023 |
| Draw the V/I characteristic curve of a p-n junction and show the procedure to calculate the forward ac resistance. | 2024 | |
| What is minority carrier storage time of a diode? How does it limit the performance of a switching diode? | 2023 | |
| Show that the dynamic resistance of a diode is , where the symbols have their usual meanings. | 2023 |
Topic 2: Diode Circuits and Special Diodes
This section focuses on the application of diodes in rectifiers, logic gates, and regulators, as well as special purpose diodes like Zeners and Tunnel diodes.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Definitions | What is Zener region? | 2022, 2024 |
| Write short note on: (i) Tunnel diode, (ii) Varactor diode. | 2022 | |
| What is varactor diode? Describe the operation of a voltage controlled tuning with varactor diode. | 2023 | |
| Breakdown Mechanisms | What does mean by breakdown of a p-n junctions? Briefly describe the avalanche and Zener breakdown mechanism. | 2022, 2024 |
| A Zener diode is operated in the reverse breakdown region but it does not burn, why? | 2023 | |
| Diode Logic & Applications | Draw and explain the application of diode circuit for logical AND operation. | 2022 |
| Draw and explain the application of diode circuit for logical OR operation. | 2024 | |
| How can a junction diode be used as a protection element for LED? | 2023 | |
| Write the differences between electronics devices and integrated circuit. Explain that an ideal diode acts as a switch. | 2022 | |
| Special Diode Operations | Explain the negative resistance region of a tunnel diode. What are the applications of this region? | 2024 |
| Rectifiers & Filters | Can the transformer and load be interchanged in a bridge rectifier? Explain. | 2024 |
| Why are the filter circuits necessary in DC power supply? Show that the ripple voltage for an RC filter connected with full wave rectifier can be given by (or similar formula). | 2022, 2023, 2024 | |
| Mention different filters with their circuit diagrams. Under what conditions the capacitor filter is preferred? | 2024 | |
| Circuit Design & Problems | Design a Zener diode voltage regulator (using circuit figures provided in exams) to maintain specific output voltages (e.g., 9V, 15V) given input variations and load resistances. | 2022, 2023 |
| For the network of figure (Zener circuit), determine the range of that will maintain at 8V and not exceed the maximum power rating. | 2024 | |
| Determine currents/voltages () for various diode networks (Ideal/Si/Ge models) provided in figures. | 2022, 2023, 2024 | |
| Full-wave bridge/center-tap rectifier calculations (DC output voltage, Peak Inverse Voltage, Rectification efficiency, AC power input). | 2022, 2023, 2024 |
Topic 3: Bipolar Junction Transistors (BJT)
Questions related to BJT construction, configurations (CE, CB), biasing, and circuit analysis.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Definitions & Theory | Explain how the junctions are biased of an npn transistor. Also explain why the junctions are biased in this way? | 2023 |
| Why is load line analysis important? How will you draw dc load line on the output characteristics of a transistor? | 2023 | |
| Find the relationship in between and of BJT, where the symbols have their usual meanings. | 2024 | |
| Prove that the expression for collector current of common base connection is . | 2022, 2023 | |
| Characteristics | Explain the output characteristics of common emitter configuration with appropriate figure. | 2022 |
| Explain the input and output characteristics of common emitter configuration with appropriate figures. | 2024 | |
| Circuit Analysis | Calculate the base, collector, and emitter currents and the CE voltage for a common emitter circuit (as shown in Figures). | 2022 |
| Find the state of the transistor (operating region) in the circuit shown. | 2024 | |
| Consider the transistor circuit shown where an LED is connected in series with the collector. (Calculation regarding LED state/current). | 2023 |
Topic 4: Field Effect Transistors (FET)
Covers JFETs and MOSFETs, their differences, and operating principles.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Definitions | What is Pinch off voltage? | 2024 |
| What is meant by channel enhancement in E-MOSFET? | 2023 | |
| Comparison | What are the differences between BJT and FET? Mention some advantages of FET over BJT. | 2022, 2024 |
| What is the primary difference between D-MOSFET and E-MOSFET? | 2022, 2024 | |
| JFET | Explain the working principle and output characteristics of n-channel JFET. Derive the relationship between and . | 2022 |
| Explain the working principle and output characteristics of p-channel JFET. Derive the relationship between and . | 2023, 2024 | |
| MOSFET | Explain the construction, basic operation and characteristic of D-MOSFET. | 2022 |
| Describe the operation of p-channel depletion type MOSFET with appropriate figure. | 2024 | |
| Explain the construction, basic operation, and characteristic of p-channel E-MOSFET. | 2023 | |
| Problems | Sketch the transfer characteristics for an n-channel depletion-type MOSFET with given and . | 2022 |
| Determine the value of drain current for the circuit shown in Fig 8(d). | 2024 |
Topic 5: Communication Systems
This broad topic includes analog/digital communication, transmission media, bandwidth, and noise.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Definitions & Short Notes | Define bandwidth. | 2022 |
| Write short notes on: (i) CCITT, (ii) ITU-T, (iii) ITU-R, and (iv) ITU-D. | 2024 | |
| Write the frequency range, bandwidth, and wavelength range of super high frequency (SHF) band. | 2022 | |
| System Fundamentals | Draw and explain the block diagram of digital communication system? What are the basic components of communication? | 2023 |
| Give the block diagram representation of a typical digital communication system. Also mention the advantages and disadvantages of digital transmission over its analog counterpart. | 2024 | |
| Explain asynchronous, synchronous, and isochronous transmissions. What is the example of isochronous transmission? | 2022 | |
| What are the differences between parallel and serial transmissions? | 2024 | |
| Why signals need to be carried in electronic communication systems as electromagnetic signals at different frequencies? (Necessity of modulation). | 2022 | |
| Transmission Media | Possible choice medium for long distance electronic communication include microwave, optical fiber and radio transmission. Discuss the advantages and disadvantages of each. | 2022 |
| All the signals need to be carried in electronic communication systems are electromagnetic signal at different frequencies. What are the typical medium used to carry such EM signals? Discuss with their relative advantages and disadvantages. | 2023, 2024 | |
| What are the benefits of optical fiber? Tabulate the comparisons among the guided medias. | 2022 | |
| What is optical fiber? Classify it according to the transmission characteristics. Also explain these characteristics in brief. | 2023, 2024 | |
| Draw and explain the construction of co-axial cable. Write the transmission characteristics/applications. | 2023, 2024 | |
| Noise & Impairments | Classify the types of transmission impairments (or impairments on analog and digital signals). Explain the distortion in communication system. | 2022, 2023 |
| Explain the effects of thermal and intermodulation noises on communication systems. | 2022 | |
| Explain the impact of impulse noise in communication. | 2023 | |
| Explain the impact of distortion and noise on transmitted signal of communication. | 2024 | |
| Write the comparisons between analog and digital communication systems. | 2023 | |
| Bandwidth & Capacity | Explain the bandwidth requirements for different modulation schemes in analog communication. | 2022, 2023, 2024 |
| Write the equation of channel capacity. | 2024 | |
| Transducers | Draw and explain the working principle of carbon microphone. Write the advantages and disadvantages of carbon microphone. | 2023, 2024 |
Topic 6: Digital Electronics and Number Systems
Covers binary arithmetic, logic gates, and Boolean algebra.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Logic Gates & Boolean Algebra | Explain involution and absorption theorems of Boolean algebra. | 2022 |
| Explain associative and De Morganβs theorems of Boolean algebra. | 2023 | |
| Design the exclusive-OR (X-OR) gate using NOR as a universal gate. | 2022 | |
| Design the exclusive-NOR gate using NAND as a universal gate. | 2023 | |
| What are universal gates? Design an X-OR gate using NAND as a universal gate. | 2024 | |
| Number Systems | Convert the following numbers as indicated (e.g., Decimal 249.6 to base-3, base-4, and base-7; Hex to Dec, Oct, Bin). | 2022 |
| Describe the necessity of using complements. | 2023 | |
| Why complements are necessary in digital system? | 2024 | |
| Arithmetic Operations | Perform the subtraction using 2βs complement & 1βs complement (e.g., ). | 2022 |
| Describe the subtraction using 2βs complement method: . | 2023 | |
| Perform 35/7 by using shift and subtract method of binary system. | 2023 | |
| Assuming that the computer uses 8 bit 2βs complement arithmetic, show how it would compute . | 2024 |
Topic 7: General Electronics, Amplifiers & ICs
Introductory topics regarding ICs and basic amplifier parameters.
| Subtopic | Questions | Year of Appearance |
|---|---|---|
| Definitions & ICs | Explain the evolution of integrated circuit (IC). List the applications of electronics in communication areas. | 2024 |
| What are the important terms of an amplifier? | 2023 | |
| What is the function of filters in the receiver of a communication system? | 2022 | |
| Amplifier Calculations | Explain the bandwidth calculation process of an amplifier using frequency response curve. | 2023 |
| In an amplifier, the output power is 1.5 watts at 2kHz and 0.3 watt at 20Hz, while the input power is constant at 50 mW. Calculate by how many decibels gain at 20Hz is below that at 2 kHz. | 2022 | |
| An amplifier rated at 40W output is connected to a 10 ohm speaker. (i) Calculate the input power required for full power output if the power gain is 25db. (ii) Calculate the input voltage for rated output if the amplifier voltage gain is 40 db. | 2023 | |
| A certain amplifier has voltage gain of 15db. If the input signal voltage is 0.7V, what is the output voltage? | 2024 |