Intro to Diode Rectifier

• rectifier circuit


  is a circuit which rectifies ac voltage by rectification
• rectification - correction of errors or mistakes
• when you rectify ac voltage you get dc voltage
• to overcome the pulsating dc we use filter to remove the pulsating dc
• its easy to transmit ac power to long distances
• stages of dc power supply

  transformer-rectifier-filter-voltage regulator-load
• transformer is used to bring level of ac voltage to desired value
• to increase the level of ac voltage you can use step up transformer
• to decrease the ac level we can use step down transformer
• filter is use to smoothen out the pulsating dc
• semiconductor diodes is used for rectifier
• 3 types of semiconductor

  1. half wave
  2. full wave (center tap, bridge tap)
• voltage regulator it regulates the voltage level even if load changes
• zener diode are used as voltage regulator
• half wave rectifier


  only one of the ac voltage is rectified, for the other half we get zero voltage
• The location of the Zener region can be controlled by varying the doping levels. An increase in doping, producing an increase in the number of added impurities, will decrease the Zener potential
• • The Zener region is where a Zener diode operates when reverse-biased at a certain voltage known as the Zener voltage (VZ). In this region, the current flows in the opposite direction compared to a forward-biased diode.
• • Silicon is commonly used to make Zener diodes due to its higher temperature and current handling capabilities.
• Important Parameters:

  • Test Current (IZT): The current at which the Zener voltage is measured.
• Important parameters

  • Dynamic Impedance (ZZT): The small resistance at the test current level.
• important parameters

  • Knee Current (IZK): The current at which the diode starts to conduct significantly in the Zener region.
• important parameters

  • Maximum Zener Current (IZM): The maximum current the diode can handle in the Zener region.
• important parameters

  • Temperature Coefficient: Indicates how VZ changes with temperature. It can be positive (VZ increases with temperature), negative (VZ decreases with temperature), or zero.
• Temperature Effects:

  • Different Zener diodes have different temperature coefficients, which affect their performance at varying temperatures. For example, a 10V Zener diode might have its voltage change within a certain range as the temperature changes.
• • The dynamic impedance of a Zener diode decreases with increasing current in the Zener region. However, below the knee of the curve, this impedance can increase significantly.
• Zener diodes are specialized diodes designed to operate in the reverse-bias Zener region, where they maintain a stable voltage (VZ) despite changes in current.
• Their behavior and specifications are influenced by doping levels, temperature, and current, all of which are important factors when selecting and using Zener diodes.
• form factor it is the ratio of rms load voltage and average load voltage
• ripple factor


  the output current contains both ac and dc components. the ripple factor measures the percentage of ac components in the rectified output
• the ideal value of ripple factor should be zero
• The process of giving off light by applying an electrical source of energy is called electroluminescence
• • LEDs are diodes that emit light when they are forward-biased (connected with the correct voltage direction). They are commonly used in digital displays, like those in calculators, watches, and other devices.
• • In a forward-biased p-n junction (a basic type of semiconductor device), electrons and holes recombine near the junction. This recombination releases energy.
• • In materials like silicon and germanium, this energy mostly becomes heat. However, in materials like gallium arsenide phosphide (GaAsP) or gallium phosphide (GaP), a significant portion of this energy is released as visible light.
• • The LED's structure is designed to maximize light emission. The p-type material has a smaller conducting surface to allow more photons (light particles) to escape.
• • Axial Luminous Intensity (IV): This measures how bright the LED is, in units called candelas. One candela can establish an illumination of 1 footcandle over a 1 square foot area 1 foot away.
• • Luminous Efficacy (ηv): This measures how effectively the LED converts electrical power into visible light, defined as the number of lumens (light output) per watt of electrical power.
• • LEDs exhibit a forward-biased characteristic similar to regular diodes. The light intensity increases almost linearly with the forward current.
• • LEDs have a fast response time, meaning they can turn on and off very quickly, which is useful for displays and indicators.
• • The intensity of light from an LED is greatest when viewed head-on (0 degrees) and decreases when viewed from the side (90 degrees).