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Advanced Digital design

Advanced Digital design. Lecture1. Assist. Prof. Rassim Suliyev - SDU 2019. Course Materials. All needed Software and course materials will be located on http://instructor.sdu.edu.kz/~rasmus inside the Advanced Digital Design directory

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Advanced Digital design

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  1. Advanced Digital design Lecture1 Assist. Prof. Rassim Suliyev - SDU 2019

  2. Course Materials • All needed Software and course materials will be located on http://instructor.sdu.edu.kz/~rasmus inside the Advanced Digital Design directory • Materials that are used in this slides are taken from the textbook “Digital Electronics A Practical Approach with VHDL” by William Kleitz

  3. INTRODUCTION • Digital circuitry is the foundation of digital computers • Home appliances, alarm systems • heating systems, automated machine control • inventory management, medical electronics, etc… • Digital electronics evolved from transistor circuitry • easily be fabricated • designed to output one of two voltage levels • 1 - HIGH (usually +5 volts) • 0 – LOW (usually 0 Volts)

  4. Digital versus Analog Systems • Digital • operate on discrete digits • numbers • letters • symbols • etc… • deal strictly with ON and OFF • represent by 0s and 1s • Analog • measure and respond to continuously varying electrical or physical magnitudes • Temperature • Pressure • Velocity • Position • Etc…

  5. Digital versus Analog Systems So why do we need to use digital representations in a world that is naturally analog?

  6. Digital Representations of Analog Quantities

  7. Noises

  8. Review Questions • Complete the following sentences with the word analog or digital: • Wind speed is an example of a(an) _______ quantity? • A music CD contains _______ information? • A USB connector transmits _______ data? • Hourly outdoor air temperatures exhibit _______ variations? • An automobile speedometer display is (digital, analog, or could be either) • An analog-to-digital converter outputs an analog voltage. True or false?

  9. Number Conversions • octal • hexadecimal binary

  10. BCD and Symbol Represenation The binary-coded-decimal (BCD) system is used to represent each of the 10 decimal digits as a 4-bit binary code. This code is useful for outputting to displays that are always numeric (0 to 9), such as those found in digital clocks or digital voltmeters. ASCII - American Standard Code for Information Interchange The ASCII code uses 7 bits to represent all the alphanumeric data used in computer I/O.

  11. Digital Signals • A digital signal is made up of a series of 1s and 0s that represent numbers, letters, symbols, or control signals

  12. Clock Waveform Timing • Special clock and timing circuits are used to produce clock waveforms to trigger the digital signals at precise intervals

  13. Serial vs Parallel Serial Parallel • uses a single electrical conductor • can only transmit 1 bit for each clock period • generally used in computer-to-computer communication • uses a separate electrical conductor for each bit to be transmitted, thus is fast • generally used in data transfer inside the computer

  14. Review Questions • Why is ASCII code required by digital computer systems? • What is the relationship between clock frequency and clock period? • What advantage does parallel have over serial in the transmission of digital signals?

  15. Switches in Electronic Circuits • transitions between 0 and 1 are caused by switching from one voltage level to another (0V, 5V) • make and break a connection between two electrical conductors • manual switch • electromechanical relay • semiconductor devices (diodes, transistors)

  16. A Relay as a Switch • controlled by external voltage • often used to deliver signals to a high power load

  17. A Relay as a Switch • Advantage: it provides total isolation between the triggering source and the output • Disadvantages: • High power consumption (triggering device must supply several mA whereas a semiconductor requires only a few uA to operate) • Speed (take several ms to switch, compared to us for a semiconductor switch)

  18. A Diode as a Switch • semiconductor device that allows current to flow only in one direction • current will flow only if the anode is more positive than the cathode

  19. 1. Determine if the diodes are forward or reverse biased? 2. Determine V1-V6 (with respect to ground) for the circuits?

  20. A Transistor as a Switch • three-terminal semiconductor component • allows an input signal at one of its terminals to cause the other two terminals to become a short or an open circuit • commonly made of silicon • N-type (one more electron) • P-type (one less electron) • three distinct regions • emitter, base, collector • N-P-N-type or P-N-P

  21. NPN vs PNP • NPN transistor • applying a positive voltage from base to emitter causesthe collector-to-emitter junction to short (turn ON) • applying a negative voltage or 0 V from base to emitter causes the collector-to-emitter junction to open (turn OFF) • PNP transistor • applying a negative voltage from base to emitter turns it ON. • applying a positive voltage or 0 V from base to emitter turns it OFF

  22. A Transistor as a Switch

  23. The TTL Integrated Circuit • TTL (Transistor–transistor logic) • use a combination of several transistors, diodes, and resistors integrated together in a single package • Q1 - input transistor (drives Q2) • Q2 controls Q3 and Q4 • D1 protects Q1 • from negative voltages • D2 ensures Q4 cut off • when Q3 is saturated

  24. The idea of needing a variable RC resistance is accommodated by the TTL integrated circuit. It uses another transistor (Q4) in place of RC to actlike a varying resistance. Q4 is cut off (acts like a high RC) when the output transistor(Q3) is saturated, and then Q4 is saturated (acts like a low RC) when Q3 is cut off.

  25. The CMOS Integrated Circuit • CMOS – complementary metal oxide semiconductor • uses a complementary pair of metal oxide semiconductor field-effect transistors (MOSFETs) • advantage is its low power consumption • disadvantages compared to TTL: • switching speed is slower • burnout due to electrostatic charges • Details about TTL and CMOS • discussed later in further lectures

  26. Integrated Circuit Chips

  27. Review Questions • How does a normally open relay differ from a normally closed relay? • To forward bias a diode, the anode is made more ___________ (positive/negative) than the cathode. • To turn ON an NPN transistor, a ___________ (positive/negative) voltage is applied to the base.

  28. Simulation of Switching Circuits • MultiSIM - software simulation tool • provides an accurate simulation of digital and analog circuit operation • simulation of instruments to measure IC, component, and circuit characteristics Download and install from: http://instructor.sdu.edu.kz/~rasmus/ Follow Advanced Digital Design -> Software directories

  29. Grading Policy • MT1 – 30% • Class work (until week 8) – 15% • Paper based Midterm (on week 8) – 15% • MT2 – 30% • Class work (weeks 9 - 15) – 15% • Attendance (weeks 1-15) – 15% • FIN – 40% • Project – 20% • Paper based Final Exam – 20%

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