3130704 Digital Fundamentals By Dr Rutvij C Joshi

3130704: Digital Fundamentals By Dr. Rutvij C. Joshi Associate professor Electronics & Communication Department A. D. Patel Institute of Technology New V V Nagar

Unit-1 Fundamentals of Digital Systems and Logic Families Digital Signals: • A digital Signal is defined as the signal which has only a finite number of distinct values • Digital Signals are not continuous signal. They are discrete signals as shown into the figure given below

Digital Signals Binary Signal: • If a digital signal has only two distinct values (i. e “ 0” and “ 1”) then it is called as binary signal. Octal Signal: • If a digital signal having eight distinct values is called as an Octal Signal Hexadecimal Signal: • If a digital signal having sixteen distinct values is called as an Hexadecimal Number.

Digital Signals Advantages of Digital Signals • Digital signals can be processed and transmitted more efficiently and reliably than analog signals. • It is possible to store the digital data. • Play back or further processing of the digital data is possible. • Digital signals are less vulnerable to noise, so digital data can travel longer distance with less attenuation.

Digital Systems • Digital system is the system which processes or works on the digital signals. • The input and output signal of the digital system is digital. Digital input signal Digital Circuit Digital output signal

Digital Systems Examples of Digital Systems: • Communication System • Traffic Control • Industrial Applications • Medical Applications • Business Transactions • Weather Monitoring

Digital Signals Advantages of Digital Signals • Digital signals can be processed and transmitted more efficiently and reliably than analog signals. • It is possible to store the digital data. • Play back or further processing of the digital data is possible. • Digital signals are less vulnerable to noise, so digital data can travel longer distance with less attenuation.

Logic Gates Logic Gate • Logic gates perform basic logical functions and are the fundamental building blocks of digital integrated circuits. Most logic gates take an input of two binary values, and output a single value of a 1 or 0. Truth Table • The table used to represent the Boolean expression of a logic gate function is commonly called a Truth Table. • A logic gate truth table shows each possible input combination to the gate or circuit with the resultant output depending upon the combination of these input(s). • The operation of the logic gate or a logic circuit can be understood with the help of the table

Classification of Logic Gates Basic Gates - NOT Gate - AND gate - OR gate Universal Gates - NOR gate - NAND gate Special Purpose Gates - EX-OR gate - Ex-NOR gate

LOGIC GATES Symbol set 2 Symbol set 1 a AND b a (ANSI/IEEE Standard 91 -1984) a b a OR b a+b b NOT a a' a NAND NOR EXCLUSIVE OR a b a b (a b)' (a+b)' a b a a C. b Joshi, ECE Dept. Prepared By Dr. Rutvij b A. D. I. T & a b 1 a+b 1 a' & (a b)' 1 (a+b)' =1 a b 10