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Unit I: Semiconductor Diodes and Applications Before we start with Electronics Let us review the Basics of Electricity Q. What are the two main quantities in electricity ? CURRENT VOLTAGE

Unit I: Semiconductor Diodes and Applications What is Current?

Unit I: Semiconductor Diodes and Applications What is Voltage?

Unit I: Semiconductor Diodes and Applications What is a Voltage Source ? A device that produces voltage output continuously. DC Voltage Source and AC Voltage Source TYPES:-

Unit I: Semiconductor Diodes and Applications What is a Current Source ? A voltage source that has a very high internal impedance as compared with external load impedance is a Constant Current Source. Example: A dc battery of 1000 V with internal resistance 950kΩ and load resistance varying from 50 KΩ to 150 KΩ.

Unit I: Semiconductor Diodes and Applications Series and Parallel Connections 7 Two 12 V batteries in series Two 12 V batteries in parallel What will be the output voltage if a 24 V battery is connected in parallel with a 12 V battery?

Applications: - Rectification Amplification Control Generation Conversion of Light into Current Conversion of Current into Light

Unit I: Semiconductor Diodes and Applications Classification of Solids Insulators: (e.g. wood, glass) Conductors: (e.g. copper, aluminum) Semiconductors: (e.g. germanium, silcon) Conductors, Insulators and Semiconductors

Unit I: Semiconductor Diodes and Applications Semiconductors A semiconductor is a substance which has conductivity (2 to 2000/ ohm-meter) in between conductors and insulators e.g. germanium, silicon, carbon etc. A semiconductor is a substance which has almost filled valence band and nearly empty conduction band with a very small forbidden energy gap i.e. 1.1eV for silicon and 0.7eV for germanium.

Unit I: Semiconductor Diodes and Applications Intrinsic & Extrinsic semiconductors A semiconductor in an extremely pure form is known as an intrinsic semiconductor. The intrinsic semiconductor has little current conduction capability at room temperature. To be used in electronic devices, the conducting properties of intrinsic semiconductor are significantly increased by adding a small amount of suitable impurity, it is then called extrinsic semiconductor. The process of adding impurities to a pure semiconductor is known as doping. Man adding water to milk

Unit I: Semiconductor Diodes and Applications P-N Junction If a semiconductor is doped with p-type impurities at one end and n-type impurities at the other end, a p-n Junction is formed 12

Unit I: Semiconductor Diodes and Applications Diode It is a one way valve. It allows current to flow in one direction only. It is commonly used (as a switch) in making Power supply to convert ac voltage into dc voltage. 13

Unit I: Semiconductor Diodes and Applications Half-wave Rectifiers Half-wave rectifier – A diode placed in series between a transformer (or ac line input) and its load.

Unit I: Semiconductor Diodes and Applications Positive Half-wave Rectifiers This circuit converts an ac input to a series of positive pulses.

Unit I: Semiconductor Diodes and Applications Negative Half-wave Rectifiers This circuit converts an ac input to a series of negative pulses.

Unit I: Semiconductor Diodes and Applications Full-wave Rectifier

Unit I: Semiconductor Diodes and Applications Negative Full-wave Rectifiers The negative full-wave rectifier converts an ac input to a series of negative pulses.

Unit I: Semiconductor Diodes and Applications Full-Wave Bridge Rectifiers The most commonly used because: It does not require the use of a center-tapped transformer. It can be coupled directly to the ac power line. It produces a higher dc output than a comparable full-wave center-tapped rectifier.

Unit I: Semiconductor Diodes and Applications Transistors 20

Unit I: Semiconductor Diodes and Applications Digital Circuits Digital circuits are prepared using analog components like transistor as a switch. The binary numbers 1 and 0 are represented by +5Volts and 0Volts. 21

Unit I: Semiconductor Diodes and Applications THANK YOU 22