STUDY MATERIAL · GATE EC · EE · IN
GATE Digital Electronics: questions and notes
Digital Electronics questions from 21 GATE papers (2018–2026) with the official answers, each solved step by step, plus notes for each topic, a formula sheet and practice questions.
- previous-year questions
- 103previous-year questions
- solved step by step
- 103solved step by step
- GATE papers, 2018–2026
- 21GATE papers, 2018–2026
- topics with notes
- 7topics with notes
TOPICS
Seven topics, in the order they are taught
Taken from the official GATE 2027 syllabus. Each topic has notes, the formulas you need, its previous-year questions with the official answers and step-by-step solutions, and practice questions.
- GATE EC · IN only
Number systems and codes
Number systems and codes covers how a digital system stores quantities as bit patterns: positional bases and conversion between them, r's and (r−1)'s complements, unsigned and signed (2's-complement) integers, decimal and unit-distance codes (BCD, excess-3, 2421, Gray), IEEE 754 floating point, and parity-based error detection.
5 previous-year questions · 7 marks · 7 practice questions
Boolean algebra, logic gates and minimisation
Boolean algebra is the algebra of two-valued (0/1) logic: its laws (absorption, consensus, De Morgan, duality) simplify expressions, and canonical SOP/POS forms and Karnaugh maps turn a truth table into a minimal two-level circuit of gates.
22 previous-year questions · 32 marks · 6 practice questions
- GATE EC · IN only
Logic families and CMOS logic gates
Logic families are compared on a few datasheet parameters: the voltage thresholds V_IH, V_IL, V_OH, V_OL, the noise margins, fan-out, propagation delay, power and the power-delay product.
7 previous-year questions · 9 marks · 6 practice questions
Combinational circuits: arithmetic circuits, multiplexers, decoders, code converters
A combinational circuit has no memory: its outputs depend only on the inputs present now.
12 previous-year questions · 16 marks · 5 practice questions
Sequential circuits: flip-flops, counters, shift registers, state machines and timing
Sequential circuits have memory: their outputs depend on stored state as well as on the present inputs, and in a synchronous circuit flip-flops update that state at clock edges.
30 previous-year questions · 49 marks · 5 practice questions
Sample-and-hold, ADCs and DACs
Sample-and-hold circuits, DACs and ADCs link analog signals to digital logic.
18 previous-year questions · 27 marks · 6 practice questions
- GATE EC · IN only
Memories, computer organisation, microprocessors and embedded systems
This topic covers how semiconductor memories (ROM, SRAM, DRAM) store bits and are wired into an address map, how a processor encodes instructions, locates operands and sequences its datapath through a control unit, and how pipelining raises throughput; for IN it extends to microprocessors, microcontrollers, memory and I/O interfacing, embedded programming and data acquisition.
9 previous-year questions · 16 marks · 5 practice questions
QUESTIONS BY TOPIC AND YEAR
103 questions, by topic and year
How many questions each topic had in the EC, EE and IN papers of each year. This shows what was asked, not what will be asked. We placed each question under a topic ourselves; the exam paper does not label topics. Every question links back to its paper.
| Topic | 2018 | 2020 | 2022 | 2023 | 2024 | 2025 | 2026 | Total |
|---|---|---|---|---|---|---|---|---|
| Number systems | 1 | 1 | · | · | 1 | 1 | 1 | 5 |
| Boolean logic | 6 | 2 | 4 | 2 | 3 | 3 | 2 | 22 |
| Logic families | 1 | · | 2 | 1 | · | · | 3 | 7 |
| Combinational | 1 | 2 | 2 | 1 | 3 | 2 | 1 | 12 |
| Sequential | 5 | 4 | 4 | 7 | 3 | 3 | 4 | 30 |
| ADC & DAC | 1 | 4 | 2 | 3 | 2 | 4 | 2 | 18 |
| Processors & memory | 2 | 2 | · | 1 | 1 | 1 | 2 | 9 |
GATE ECE question papers with solutions: 2026, 2025, 2024, 2023, 2022, 2020, 2018
GATE EE question papers with solutions: 2026, 2025, 2024, 2023, 2022, 2020, 2018
GATE IN question papers with solutions: 2026, 2025, 2024, 2023, 2022, 2020, 2018
The 2019 and 2021 papers are not included yet: the copies we host are image scans without the official key.
Digital Electronics formulas by topic
Preparing in Kolkata? See IAE Academy’s GATE EC coaching, GATE EE coaching and GATE IN coaching.
THE OFFICIAL SYLLABUS
What each paper lists under Digital Electronics
From the GATE 2027 syllabus PDFs. EC (Section 5, “Digital Circuits”) and IN (Section 7, “Digital Electronics”) give it a section of their own; EE lists it in one line at the end of Section 9, “Analog and Digital Electronics”. EE’s syllabus names no number systems, logic families, flip-flops, counters, memories or microprocessors, only combinatorial and sequential logic circuits, multiplexers and data converters. That is why three topics are marked EC and IN only. EE papers set three such questions anyway, two on microprocessors (2020 and 2023) and one on MOSFET switch logic (2026), and we placed them under those topics.
GATE EC
Number Representations: Binary, integer and floating-point- numbers. Combinatorial circuits: Boolean algebra, minimization of functions using Boolean identities and Karnaugh map, logic gates and their static CMOS implementations, arithmetic circuits, code converters, multiplexers, decoders. Sequential Circuits: Latches and flip-flops, counters, shift-registers, finite state machines, propagation delay, setup and hold time, critical path delay. Data Converters: Sample and hold circuits, ADCs and DACs. Semiconductor Memories: ROM, SRAM, DRAM. Computer Organization: Machine instructions and addressing modes, ALU, data-path and control unit, instruction pipelining.
GATE EE
combinatorial and sequential logic circuits, multiplexers, demultiplexers, Schmitt triggers, sample and hold circuits, A/D and D/A converters.
GATE IN
Basics of number systems. Combinational logic circuits, multiplexer and demultiplexer, truth table, minimization of Boolean functions; IC families: ECL, TTL and CMOS, CMOS implementation of logic gates; arithmetic circuits, sequential circuits, finite state machines, flipflops, shift registers, timers and counters. Analog front end: analog multiplexer, programmable gain amplifier, sample-and-hold circuit; analog-to-digital converters (ADC) (successive approximation, integrating, flash and sigma-delta) and digital-to-analog converters (DAC) (weighted R, R-2R ladder and current steering logic); characteristics and specifications of ADC and DAC (dynamic range, resolution, quantization, significant bits, conversion/settling time, INL, DNL, ENOB); embedded systems: common microprocessors and microcontrollers, memory and input-output interfacing, embedded systems programming; basics of data acquisition systems, virtual instrumentation, IoT; basic AI applications in instrumentation (sensor linearization, system calibration and tuning, signal classification).
IF YOU WOULD RATHER TALK IT THROUGH