Chapter 03 - Digital Logic

Chapter 03 - Digital Logic - Chapter 3 - Digital Logic B A...

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Chapter 3 - Digital Logic B A
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 2 History of the Transistor n Around 1945, Bell Labs scientists discovered that silicon was comprised of two distinct regions differentiated by the way in which they favored current flow. n The area that favored positive current flow they named "p" and the area that favored negative current flow they named "n". n The transistor effect describes the change from a condition of conductivity (switched “on”, full current flow) to a condition of insulation (switched “off”, no current flow). The Transistor
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 3 Digital Logic Circuits n Computers = large number of simple structures n Intel 4004 = 2,300 transistors n Intel Pentium 4 = 42 million transistors n Intel Core 2 Duo = 291 million transistors n Intel i7 “Bloomfield” = 731 million transistors The Transistor
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 4 Moore’s Law Early 1900’s 1947 1950’s Moore’s Law: The number of transistors per area doubles every 1.5 - 2 years. 1960’s 1970’s 1980’s 1990’s 2000’s The Transistor 2010’s
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c u r e n t f l o w gate N-type Transistor BYU CS/ECEn 124 Chapter 3 - Digital Logic 5 The MOS Transistor n A transistor acts like a switch n Conducts current when "ON" n No current flow when "OFF" MOS = metal-oxide semiconductor CMOS = complementary MOS with both N and P transistors The Transistor Complementary Gate (input) FET (output) GND (0) Open Vcc (3.3v) Closed Gate (input) FET (output) GND (0) Closed Vcc (3.3v) Open gate P-type Transistor
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B E C 0 BYU CS/ECEn 124 Chapter 3 - Digital Logic 6 N Type P Field Effect Transistor The Transistor C E B 0 B E C 1 C E B 1
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Source BYU CS/ECEn 124 Chapter 3 - Digital Logic 7 CMOS Gates Pull-up Structure (P-Type) Pull-down Structure (N-Type) C omplementary The “C” in CMOS Even in the digital world, "EVERYTHING IS ANALOG"! The Transistor 1 0 n Complementary pull-up / pull-down logic n pull-down is " ON" when pull-up is "OFF " n and vise versa.
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 8 The Inverter in 1 0 out 0 1 0 1 on off 1 1 0 0 on off This is a truth-table. It tells what the output will be for all combinations of the inputs. Inverter Symbols Symbols are abstractions! Digital Logic Devices In out 0 1 1 0
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 9 The NOR Gate ( NOT-OR ) NOR Symbols a b 1 0 0 NOR Digital Logic Devices on off off on 1 0 0 1 0 0 off off on on 0 a b 1 0 0 a b NOR 0 0 1 0 1 0 1 0 0 1 1 0
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 10 The OR Gate Digital Logic Devices a b OR 0 0 0 0 1 1 1 0 1 1 1 1 OR Symbol n How do you build an OR gate? a b 1 0 0 a b OR 1 0 OR
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 11 The NAND Gate ( NOT-AND ) on off off on 1 1 0 1 1 0 1 0 1 1 1 0 off off on on b a 1 1 0 NAND NAND Symbols Digital Logic Devices a b NAND 0 0 1 0 1 1 1 0 1 1 1 0
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BYU CS/ECEn 124 Chapter 3 - Digital Logic 12 The AND Gate n How do you build an AND gate?
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Chapter 03 - Digital Logic - Chapter 3 - Digital Logic B A...

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