Electronic Circuits – ELEC 10004.2 PDF

Electronic Circuits – ELEC 10004.2 Unit 1: Diode Applications  Disclaimer The PowerPoint presentations of the Module Electronic Circuits (ELEC 10004.2) are created merely to guide me during the delivery of this module in my class. The content included in th...

Electronic Circuits – ELEC 10004.2 Unit 1: Diode Applications  Disclaimer The PowerPoint presentations of the Module Electronic Circuits (ELEC 10004.2) are created merely to guide me during the delivery of this module in my class. The content included in the slides are only indicative to remind me the sequence which I will be following during the delivery. The content presented in the slides is free from any plagiarism and copyright violations and wherever needed appropriate referencing/citations have been provided. In addition to the content in this PowerPoint presentations, I will also be verbally delivering other important content in the class as well as also writing on the board, some information related to the topic being covered wherever necessary. The student is therefore advised to refer to the text books, reference books and any supplementary materials recommended in the Module Information Guide (MIG) or in the PowerPoint presentations for complete understanding of the topic.  Unit overview Learning Outcomes: Classify various applications of pn-junction diode Interpret and outline electronic Activity: circuits using semiconductor Quiz devices considering the environmental implications of the design; and Text Book: Robert Boylestad and Louis UNIT 1 Assessment1 Nashelsky, Electronic Devices and Circuit Theory UNIT 2 http://www.learnerstv.com/ UNIT 3 MOOC: Free-Engineering-Video- UNIT 4 UNIT 5 Introduction to Electronics lectures-ltv052-Page1.htm UNIT 6  Academic Integrity Violation Plagiarism Submit only MS Word document. Do not share your work with other students as plagiarism applies to all. Do not upload same assessment in multiple or wrong links Do not copy text from any source. Do not replace text, codes, mathematical equation, etc. with screenshots. Do not add border, watermarks or any other form of tampering as other tools can detect similarity even with such inclusion. Note: Refer Students Hand book Part A: clause 5.9 and 5.10 for detailed Policy and Penalties  Academic Integrity Violation … 2 Plagiarism Only one students must upload in group assignments. Adding border or watermarks in report will result in deduction of marks for not confirming to report format Whether the work is mentioned, described, reproduced, summarized, paraphrased or directly quoted, Provide proper citation and references in CU Harvard style Malpractice/Ghostwriting/Collusion and other cases Note: Refer Students Hand book Part A: clause 5.9 and 5.10 for detailed Policy and Penalties  Grading, Attendance, Late Submission Late submission (Refer Students Hand book Part B: clause 4.2 for detailed Policy and Penalties) Attendance (Refer Students Hand book Part A: clause 5.7 for detailed Policy and Penalties) For wrongly marked attendance intimate the faculty within three days. Any intimation latter cannot be considered.  Diodes It is formed by joining n-type and p- type semiconductor together by following a suitable method. The border between p type and n type is called a PN junction. Schematic Symbol Floyd (2004) 8  Diodes At the p-n junction, the excess conduction- band electrons on the n-type side are attracted to the valence-band holes on the p-type side. The electrons in the n-type material migrate across the junction to the p-type material (electron flow). The electron migration results in a negative charge on the p-type side of the junction and a positive charge on the n-type side of the junction. Floyd (2004) 9  Depletion Region At the instant the two materials are “joined” the electrons and the holes in the region of the junction will combine, resulting in a lack of free carriers in the region near the junction once the free carriers have been absorbed only positive and the negative ions remaining in this region. This region of uncovered positive and negative ions is called the depletion region due to the “depletion” of free carriers in the region. Floyd (2004) 10  Barrier Potential It is the potential at the PN-junction which stops the movement of free electrons to cross from n-type to p-type and the holes to cross from p-type to n-type. At 25 °C the barrier potential of diodes: Germanium 0.3 volts Silicon 0.7 volts Floyd (2004) 11 Diodes Floyd (2004) 12  Biasing Techniques of the Diode Biasing is the process of supplying voltage to a circuit. Since the diode is a two-terminal device, the application of a voltage across its terminals leaves three possibilities: no bias (𝑉𝐷= 0 V), forward bias ( 𝑉𝐷˃ 0 V), and reverse bias (𝑉𝐷 < 0 V) Floyd (2004) 13 Forward bias Condition The battery pushes the holes and free electrons towards the junction. If the battery voltage is less than the barrier potential, the free electrons do not have enough energy to pass through the depletion layer. When they enter the depletion layer, the negative acceptor atoms will push them back into the n-region. Hence there is no current through the pn-junction. When the battery voltage is more than the barrier potential, the free electron has enough energy to get across the depletion layer. This results in a continuous current through the pn-junction. Forward bias Condition Floyd (2004) 14 Reverse bias Condition The negative terminal of the battery attracts the holes and the positive terminal of the battery attracts the free electrons. Due to this the free electrons and holes move away from the junction. Therefore the depletion region gets wider. The wider the depletion region, the greater is the barrier potential. Hence very difficult for majority carriers to move across the junction. Reverse bias Condition 15 Volt-Ampere (V-I) Characteristics of a PN- junction Volt-Ampere (V-I) Characteristics Floyd (2004) 16 Diode Current Equation Floyd (2004) 17 Problem: A Ge diode carries a current of 10 mA when a forward bias of 0.2 V is applied at 293 ° K (20 ° C). Find 1.The reverse saturation current 2.The bias voltages required for diode currents of 1 mA. Diode Applications Rectifiers and Power Supplies Clipper Circuits Clamper Circuits Zener Diode 19 Rectifiers and Power Supplies A rectifier is an electrical circuit that converts alternating current (AC) to direct current (DC). Rectification is the process of converting AC to DC. Rectification Based on Diode – Rectification is most popular application of diode. – Diodes provide compact and inexpensive means of rectification. Floyd (2004) 20 Types of Rectifiers Half Wave: – Negative components of sine wave are discarded. Full Wave: Centre-Tap full wave rectifier Full wave Bridge rectifier – Negative components are inverted. Floyd (2004) 21  Rectification Circuit: Half-Wave Simplest kind of rectifier circuit is half-wave rectifier. Allows one half of AC waveform to pass through to load. Converts alternating current (AC) to direct current (DC). Involves device that only allows one-way flow of electrons, and this is exactly what semiconductor diode does. Half-wave rectifier circuit Floyd (2004) 22 Rectification Circuit: Half-Wave (Boylestad, 2012) 23 Half-wave Rectifier with transformer coupled input voltage Efficiency: Rectifier Efficiency = (Output DC Power)/ (Input AC Power) Efficiency of a half-wave rectifier = 40.6 % Floyd (2004) 24 Rectification Circuit: Half-Wave PIV (Peak Inverse Voltage) : It is the maximum reverse voltage in the circuit that the diode must withstand without damage. PIV (or PRV) > Vm PIV = Peak Inverse Voltage PRV = Peak Reverse Voltage Vm = Peak AC Voltage Disadvantages : For most power applications, half-wave rectification is insufficient for task. – Harmonic content of rectifier's output waveform is very large and consequently difficult to filter. – AC power source only supplies power to load once every half-cycle, meaning that much of its capacity is unused. Floyd (2004) 25 Rectification Circuit: Full-Wave (Boylestad, 2012) 26  Rectification Circuit: Full-Wave Disadvantages: It is difficult to find centre tap on the secondary coil of the transformer. The DC output is small as each diode uses only half of the transformer secondary voltage. 27 Full wave Rectification: Bridge Rectifier Floyd (2004) 28 Full wave Rectification: Bridge Rectifier 29 Full wave Rectification: Bridge Rectifier PIV/PRV ≥ Vm Floyd (2004) 30 Rectifier Comparisons Floyd (2004) 31  Clipper Circuits Clippers are used ‘clip’ away, a portion of the input signal, without distorting the remaining part of the applied waveform. Floyd (2004) 32 Series Clipper - Example Floyd (2004) 33 Series Clipper - Example 34 Parallel Clipper - Example Floyd (2004) 35  Clamper Circuits The clamping network will “clamp” a signal to a different dc level. Applications: Used to restore lost DC levels in signals from transmission (eg. Television) The magnitude of R and C must be chosen such that the time constant RC is large enough to ensure that the voltage across the capacitor does not discharge significantly during the interval when diode is not conducting. Floyd (2004) 36 Clamper Circuit - Example Floyd (2004) 37  Zener Diode A Zener diode is a type of diode that permits current not only in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as “Zener voltage” (Vz) Floyd (2004) 38 Example Floyd (2004) 39  Formative Assessments Quiz References Robert Boylestad and Louis Nashelsky. Electronic Devices and Circuit Theory. 11th Edition. Pearson Education, 2012. Floyd, Thomas L. Electronic Devices. 9th Edition. Prentice Hall, 2011. Thank You!