Digital Circuits Notes – Complete Guide for ECE, GATE & PGCET
Digital Circuits (also known as digital electronics) form the foundation of modern computers, embedded systems, and communication devices. If you are preparing for GATE, TS PGCET, or B.Tech ECE exams, these notes will give you a complete overview of the subject in a structured way.
📌 Why Study Digital Circuits?
Digital circuits are everywhere – from your mobile phone processor to memory chips. Understanding them helps in:
Cracking competitive exams like GATE, TS PGCET, ESE.
Building a strong foundation for VLSI, Computer Architecture, and Embedded Systems.
Practical applications in processors, controllers, and communication systems.
📚 Digital Circuits Syllabus & Notes
1. Number Systems and Codes
Binary, Octal, Decimal, Hexadecimal conversions
1’s & 2’s Complement, Signed Magnitude representation
Binary arithmetic (addition, subtraction, multiplication, division)
Codes: BCD, Gray, Excess-3, ASCII
Error detection and correction (Parity, Hamming Code)
2. Logic Gates
Basic gates: AND, OR, NOT
Universal gates: NAND, NOR
XOR & XNOR
Realization of Boolean functions using gates
3. Boolean Algebra & Minimization
Boolean laws & theorems
SOP & POS forms
K-Map simplification (2, 3, 4 variables)
4. Combinational Circuits
Half Adder, Full Adder, Subtractor
Multiplexer (MUX), Demultiplexer (DEMUX)
Encoder, Decoder, Priority Encoder
Comparators
Arithmetic Logic Unit (ALU) basics
5. Sequential Circuits
Flip-Flops: SR, JK, D, T, Master-Slave
Excitation tables & conversion
Registers: SISO, SIPO, PISO, PIPO
Counters: Asynchronous, Synchronous, Mod-n, Ring.
6. Memory & Programmable Devices
ROM, RAM, EPROM, EEPROM
Static RAM (SRAM) vs Dynamic RAM (DRAM)
Programmable devices: PLA, PAL, FPGA
7. Timing Analysis
Propagation delay
Setup & hold times
Clock frequency & duty cycle
Hazards & glitches
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✅ Conclusion
Digital Circuits is one of the most important subjects for electronics students and competitive exams. With these notes, you can cover everything from the basics of number systems to advanced concepts like memory and programmable devices.
Keep revising, practice previous year GATE/PGCET questions, and use K-Maps & truth tables to simplify logic.
