surface acoustic wave technology

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  1. 1. Surface Acoustic Wave Technology Presented By: AKHIL BARAIK
  2. 2. Outline Introduction Terminology Surface Acoustic Wave(SAW) - Components - Properties SAW Principle Applications Advantages & Disadvantages Conclusion References Outline
  3. 3. Outline Surface Acoustic Wave Technology Brief History: Surface Acoustic Waves (SAW) were discovered in 1885 by Lord Rayleigh SAW device was invented by White and Voltmer in 1965 Around 1970, developed for Pulse Compression Radar, oscillators, and bandpass filters for domestic TV Diverse applications in consumer and highly professional electronic devices and systems Perform different functions in the frequency range from 10 MHz to several GHz. Introduction
  4. 4. Outline Continued... Terminology Surface: Outside part or uppermost layer of something. Acoustic : Science deals with the study of all mechanical waves in gases, liquids, and solids. Wave: Oscillation accompanied by transfer of energy that travels through space or mass. Acoustic Wave : Type of longitudinal wave propagates by means of adiabatic compression and decompression. Introduction
  5. 5. Outline Definition A Surface Acoustic Wave (SAW) is an Acoustic Wave traveling along the surface of an elastic substrate. Frequency of SAW: F=V/ V=Velocity of SAW (~ 2500m/s-10000m/s) =wavelength Type of mechanical wave motion travels along the surface of solid material. Surface Acoustic Wave(SAW)
  6. 6. Outline SAW Device . Fig : Basic Structure of SAW Device Surface Acoustic Wave(SAW)
  7. 7. Outline Continued... SAW Device? A solid state device Converts electrical energy into a mechanical wave(Acoustic) on a single crystal substrate and vice versa Provides very complex signal processing in a very small volume Approximately 4-5 billion SAW devices are produced each year Surface Acoustic Wave(SAW)
  8. 8. Outline SAW Device Components Transducers(IDT) Piezoelectric Substrate Crystal Quartz(SiO2) Lithium Niobates(LiNbO3) Lithium Tantalates(LiTaO3) etc. Reflectors Surface Acoustic Wave(SAW) Fig : Typical Piezoelectric Transducer Fig : SAW Reflector Gratings
  9. 9. Outline SAW Properties Piezoelectric Substrate : Acoustoelectric Conversion Small Surface Perturbation: 0.1-20 A0 Velocity: ~2,500 -10,000 m/s Efficient Transduction Frequency Range: ~10MHz to 3GHz Surface Acoustic Wave(SAW)
  10. 10. Outline SAW Comparison with EM wave Vsaw=~3000 m/s Vem=~3 x108 m/s F =V Surface Acoustic Wave(SAW) F=10MHz F=1GHz saw 300 m 3m EM 30m 3m
  11. 11. Outline SAW Principle Based on Piezoelectric Effect: Useful in applications: production and detection of sound generation of high voltages etc Based on Acoustic Wave : Wave propagates by means of adiabatic compression and decompression. SAW Fundamentals
  12. 12. Outline Continued... Piezoelectric Effect Also called as Piezoelectricity The ability of certain materials to generate an voltage when subjected to mechanical stress Reverse is also true. SAW Fundamentals Fig : Piezoelectric Effect
  13. 13. Outline SAW Touch Screen SAW Filter Delay Line Resonator Sensors RFID Applications
  14. 14. Outline SAW Touch Screen Application An electronic visual display locates the coordinates of users touch within display area Works independently of what is being displayed on screen
  15. 15. Outline Continued... SAW Based Touch Screen Application
  16. 16. Outline Continued... SAW Touch Screen Surface consists of glass overlay with transmitting and receiving transducers Electrical signals sent to the transmitting transducers Waves are directed across screen by reflectors then directed to receiving transducers Application
  17. 17. Outline Continued... SAW Touch Screen When finger touches screen it absorbs waves Received values are compared to stored digital maps to calculate x and y coordinates Application
  18. 18. Outline Continued... Illustration Application
  19. 19. Outline Application of SAW Touch Screen ATMs Amusement Parks Gaming Environments kiosks Industrial Control Rooms Application
  20. 20. Outline Why SAW Touch Screen? Advantages: Best optical quality High surface durability Activated by multiple sources High touch-life Disadvantages: Expensive Contaminates on screen can cause false-touches Non conductive material can not activate screen Application
  21. 21. Outline Surface Acoustic Wave ADVANTAGES: Low Velocity Low attenuation Low cost Simple design and fabrication Low power consumption DISADVANTAGES: Can not be operated in liquids Piezoelectric substrates are temperature dependent ADVANTAGES & DISADVANTAGES
  22. 22. OutlineCONCLUSION Surface Acoustic Wave Technology is widely used technology. Applied to design filters, different sensors, resonators, delay lines and many commercial devices. Most emerging technology across the world. All the electronics equipments and devices use SAW technology. The demand of SAW technology will never abate because of its fruitful advantages than disadvantages.
  23. 23. Works Cited