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Introduction to Logic Gates

Introduction to Logic Gates. Logical gates Inverter AND OR NAND NOR Exclusive OR (XOR) Exclusive NOR (XNOR) Draw Logic Circuit Analysis of Logic Circuit. Introduction to Logic Gates. Universal gates NAND and NOR NAND gate NOR gate Execution using NAND gate Execution using NOR gate

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Introduction to Logic Gates

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  1. Introduction to Logic Gates • Logical gates • Inverter • AND • OR • NAND • NOR • Exclusive OR (XOR) • Exclusive NOR (XNOR) • Draw Logic Circuit • Analysis of Logic Circuit MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  2. Introduction to Logic Gates • Universal gates NAND and NOR • NAND gate • NOR gate • Execution using NAND gate • Execution using NOR gate • Positive & Negative Logic • SOP Expression Execution • POS Expression Execution • Integrated Logic Circuit Family MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  3. Logic Gates MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  4. Logic Gates • Inverter gate • The use of inverter: complement MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  5. Logic Gates • AND gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  6. Logic Gates • OR gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  7. Logic Gates • NAND gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  8. Logic Gates • NOR gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  9. Logic Gates • Exclusive OR (XOR) gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  10. Logic Gates • Exclusive NOR (XNOR) gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  11. Draw Logic Gates • When Boolean expression is obtained, we can draw logic gates • Example: • F1 = xyz’ (use three input AND gate) MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  12. Draw Logic Gates MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  13. Logic Circuit Analysis • When logic circuit is given, we can analyze the circuit to obtain logical expression • Example: • What is the Boolean expression for F4 MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  14. Logic Circuit Analysis • What is the Boolean expression for F5 MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  15. Universal Gates: NAND & NOR • Gate AND/OR/NOT is enough to build any Boolean function • Even though, other gates is also used because: • Very useful (no choice) • Save transistor’s number • Self sufficient (can build any gate from it) NAND/NOR: save, self sufficient XOR: useful (e.g. execute parity bit) MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  16. NAND Gate • NAND gate is self sufficient (i.e.can build any gate from it) • Can be used for building AND/OR/NOT gate • Build NOT gate using NAND gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  17. NAND Gate • Build AND gate using NAND gates • Build OR gate using NAND gates MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  18. NOR Gate • NOR gate is also self sufficient • Can be used for building AND/OR/NOT gate • Build NOT gate using NOR gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  19. NOR Gate • Build AND gate using NOR gates • Build OR gate using NOR gates MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  20. Build using NAND gate • It is not impossible to build Boolean expression using NAND gates Steps • Obtain sum-of-product Boolean expression • E.g: F3 = xy’ +x’z • Use DeMorgan theorem to get expression using two level NAND gate • E.g: F3 = xy’ +x’z = (xy’+x’z)” = ((xy’)’.(x’z)’)’ MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  21. Build using NAND gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  22. Build using NOR gate • It is not impossible to build Boolean expression using NOR gates Steps • Obtain product-of-sum Boolean expression • E.g: F6 = (x+y’).(x’+z) • Use DeMorgan theorem to get expression using two level NAND gate • E.g: F3 = (x+y’).(x’+z) =((x+y’).(x’+z))’’ = ((x+y’)+(x’+z)’)’ MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  23. Build using NOR gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  24. Positive & Negative Logic • In logic gate, most of the time • H (High Voltage, 5V) = logic 1 • L (Low Voltage, 0V) = logic 0 • This is called positive logic • However, if it is inverted, it is negative logic • H (High Voltage, 5V) = logic 0 • L (Low Voltage, 0V) = logic 1 • Depends, some similar gate need different Boolean function MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  25. Positive & Negative Logic • Signal which is set to logic 1 is said to be active and true • Signal which is set to logic 0 is said to be not active and false • The name of active high signal is always written in non-compliment form • The name of active low signal is always written in non-compliment form MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  26. Positive & Negative Logic MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  27. Construction of SOP Expression • Sum-of-product expression can be built using • Two level logic gate AND-OR • Two level logic gate AND-NOT • Logic AND-OR gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  28. Construction of SOP Expression • NAND-NAND circuit (with transformation circuit) • Add two balls • Change OR with NAND with inverted input and ball on it’s compliment input MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  29. Construction of POS Expression • Product-of-sum expression can be built using • Two level logic gate AND-OR • Two level logic gate AND-NOT • Logic AND-OR gate MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

  30. Construction of POS Expression • NOR-NOR circuit (with transformation circuit) • Add two balls • Change AND with NOR with inverted input and ball on it’s compliment input ”: MOHD. YAMANI IDRIS/ NOORZAILY MOHAMED NOOR

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