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Unformatted text preview: ECE 301 – Digital Electronics Basic logic operations, Transistors, and CMOS logic gates (Lecture #4) Learning Objectives • Logic operations • Transistors – BJT – MOSFET • CMOS logic gates and logic circuits • Standard logic gates and logic families Spring 2012 ECE 301  Digital 2 Reading Roth & Kinney Sections 2.2, 3.2, 7.2 Appendix A Spring 2012 ECE 301  Digital 3 Basic Logic Operations Spring 2012 ECE 301  Digital 4 AND Definition : the output is true (1) iff both inputs are true (1). F = A.B = AB = “A and B” Boolean expression logical operator A B A . B 1 1 1 1 1 Truth table F Symbol (aka. logic gate) Spring 2012 5 ECE 301  Digital OR Definition : the output is true (1) if either or both inputs are true (1). F = A+B = “A or B” Boolean expression logical operator A B A + B 1 1 1 1 1 1 1 Truth table Symbol F F Spring 2012 6 ECE 301  Digital NOT Definition : the output is true (1) if the input is false (0), and vice versa. F = A' = “ not A” Boolean expression logical operator A A' 1 1 Truth table Symbol A F = A' Spring 2012 7 ECE 301  Digital Order of Precedence The order of precedence of the basic logic operations is defined as follows: – NOT – AND – OR The order of precedence can be modified by using parenthesis. Spring 2012 8 ECE 301  Digital Functionally Complete The AND, OR, and NOT operations comprise a functionally complete set. All logic functions can be expressed in terms of these logic operations. All logic circuits can be realized using the associated logic gates. There are, however, additional (more complex) logic gates. Spring 2012 9 ECE 301  Digital Additional Logic Gates Spring 2012 ECE 301  Digital 10 NAND Definition : the output is false (0) iff both inputs are true (1). F = (A.B)' = “not (A and B)” Boolean expression A B (A . B)' 1 1 1 1 1 1 1 Truth table F = (A.B)' Symbol shorthand for inversion Spring 2012 11 ECE 301  Digital Spring 2012 ECE 301  Digital 12 NOR Definition : the output is false (0) if either or both inputs are true (1). F = (A+B)' = “not (A or B)” Boolean expression A B (A+B)' 1 1 1 1 1 Truth table Symbol F F F F = (A+B)' shorthand for inversion Spring 2012 ECE 301  Digital 13 XOR Definition : the output is true (1) if either but not both inputs are true (1)....
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This note was uploaded on 03/26/2012 for the course ECE 301 taught by Professor Staff during the Spring '08 term at George Mason.
 Spring '08
 Staff
 Gate, Transistor

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