STUDY MATERIAL · GATE EC · EE · IN
GATE Digital Electronics previous year questions and notes
Every Digital Electronics question from 21 GATE papers (2018–2026), solved step by step and checked against the organising institute’s official answer key — with notes for each topic, a formula sheet and practice questions.
- previous-year questions
- 103previous-year questions
- worked solutions, checked against the key
- 103worked solutions, checked against the key
- GATE papers, 2018–2026
- 21GATE papers, 2018–2026
- topics with notes
- 7topics with notes
TOPICS
Seven topics, in the order they are taught
Cut from the official GATE 2027 syllabus. Each topic has notes, the formulas you need, every previous-year question on it with a checked solution, and practice questions.
- TOPIC 01EC · IN SYLLABUS 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
- TOPIC 02
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
- TOPIC 03EC · IN SYLLABUS 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
- TOPIC 04
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
- TOPIC 05
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
- TOPIC 06
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
- TOPIC 07EC · IN SYLLABUS 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
WHERE THE QUESTIONS FALL
103 questions, by topic and year
Counts across the EC, EE and IN papers of each year. A count of what was asked, not a forecast of what will be. The topic tags are IAE’s reading of each question, and 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 yet included: the copies we host are image scans that do not carry the official key, so no solution to them could be checked.
How we check solutions: editorial standards.
Digital Electronics formulas by topic
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THE OFFICIAL SYLLABUS
What each paper lists under Digital Electronics
Verbatim 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 — which 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 they are filed 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).
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