Posts tagged “gate”

38 posts.

How Far Does the Fermi Level Move When You Dope Silicon?

Each tenfold rise in doping moves silicon's Fermi level by 59.5 mV, since EF − Ei = kT ln(ND/ni): 0.347 eV for 10¹⁶ donors. Worked numbers, limits and mistakes.

7 min read

How Many Flip-Flops Does a Mod-N Counter Need?

A mod-N counter needs ⌈log₂N⌉ flip-flops: 4 for mod-10, 7 for mod-100. Why ripple counters pass through wrong counts on the way, and how to read them safely.

7 min read

Why Does a Zener Diode Hold Its Voltage, and When Does It Stop?

In breakdown a Zener's current can swing widely while its voltage barely moves, but only above a minimum. A worked regulator design shows where it stops.

7 min read

How to Check Your GATE 2027 Response Sheet Against the Answer Key

Where your GATE 2027 responses and the answer key appear, how to mark each MCQ, MSQ and NAT answer against the key, and how to add up your raw marks. From the GATE 2027 brochure.

5 min read

How Do You Enter Answers and Use the Virtual Calculator in GATE?

How GATE 2027 takes MCQ, MSQ and NAT answers, every key on the official virtual calculator, why you type the number before the function, and the slips that cost NAT marks. With the official calculator, the mock test and a practice calculator.

8 min read

Why Can't AM Put More Than a Third of Its Power in the Sidebands?

In standard AM the sideband share is μ² ÷ (2 + μ²), and μ can't pass 1 without distortion, so it tops out at 1/3. The derivation and a worked 10 V example.

6 min read

How Does a Diode's Small-Signal Resistance Change With Bias Current?

A diode's small-signal resistance is rd = nVT ÷ ID: 258.5 Ω at 0.1 mA, 25.85 Ω at 1 mA, 2.585 Ω at 10 mA. The derivation, a worked example and when it fails.

7 min read

Why Does the Early Effect Give a BJT a Finite Output Resistance?

Raising VCE narrows the base, so IC creeps up and the BJT's output resistance is ro ≈ VA ÷ IC. The physics, a worked 50 V example and the effect on gain.

7 min read

Why Does a Fourier Series Overshoot by 9% at Every Jump?

The Gibbs overshoot: a square wave's partial sums peak near 1.179, about 9% of the jump, at any number of terms. Computed sums, a worked peak and the traps.

7 min read

How Does a Hamming (7,4) Syndrome Point to the Flipped Bit?

Each Hamming parity bit checks the positions whose binary index has that bit set, so the syndrome spells out the flipped position. A worked (7,4) example.

7 min read

What Do Students Get Wrong About Don't-Cares in K-Maps?

Don't-cares in a K-map are optional 1s, not compulsory ones. Four common mistakes, a worked example checked by brute force, and why minimal answers can differ.

7 min read

How Much Does the Miller Effect Cut Common-Emitter Bandwidth?

A 2 pF base-collector capacitance can act like 195 pF at a CE amplifier's input. A worked Miller effect example, the bandwidth it costs and how exact it is.

8 min read

How Does the Nyquist Criterion Handle a Pole on the jω Axis?

Indent the Nyquist contour around the pole, then map the detour: it becomes an infinite arc closing clockwise. Worked K/(s(s+1)(s+2)) example, stable for K < 6.

8 min read

Why Does an Op-Amp Integrator Saturate, and How Long Does It Take?

An ideal integrator has infinite DC gain, so any DC input ramps it into a rail: 0.5 V into 10 kΩ and 100 nF hits −12 V in 24 ms. The offset trap and the Rf fix.

7 min read

What Do You Do When a Routh Array Has a Zero in the First Column?

A lone zero in the Routh first column gets an ε; a whole zero row needs an auxiliary polynomial. Worked examples checked against the real roots, and the traps.

7 min read

Why Does Resistance Lower Q in Series RLC but Raise It in Parallel?

Series Q = ω0L/R falls as R rises; parallel Q = R/(ω0L) rises. Why, with one worked tank: L = 1 mH, C = 10 nF, Q = 31.6 at 10 Ω series or 10 kΩ in parallel.

7 min read

How Do You Calculate Setup and Hold Slack for a Flip-Flop Path?

Setup slack uses the slowest path and the clock period; hold slack uses the fastest path and no period. A worked 5 ns example with skew gives 0.9 and 0.05 ns.

7 min read

Why Does Copper at 1 GHz Carry Current in Only a 2 µm Layer?

Skin depth δ = 1/√(πfμσ) shrinks as 1/√f: copper's is 9.35 mm at 50 Hz, 66.1 µm at 1 MHz and 2.09 µm at 1 GHz. Where it comes from and what it does to a wire.

7 min read

How Do You Find Thevenin Resistance With No Independent Source?

With only dependent sources, Voc and Isc are both zero, so Voc ÷ Isc gives 0 ÷ 0. Use a test source: the method, a worked GATE EC example and the usual traps.

7 min read

How Do You Find a Load's Reflection Coefficient From Vmax and Vmin?

VSWR = Vmax ÷ Vmin gives |Γ|; the first minimum's position gives its phase. Worked 50 Ω line: VSWR 3, |Γ| = 0.5, return loss 6.02 dB, ZL = 24.05 − j30.50 Ω.

8 min read

Why Can the Same Z-Transform Belong to Two Different Signals?

A z-transform means nothing without its region of convergence: 1/(1 − az⁻¹) is aⁿu[n] or −aⁿu[−n−1]. Worked poles at 0.5 and 2, three ROCs, which is stable.

7 min read

Fourier Series for GATE Signals and Systems

Fourier series for GATE EC, EE and IN: the trigonometric and exponential forms, symmetry shortcuts, Parseval's theorem, and three worked examples including a square wave through a filter.

8 min read

GATE 2027 Eligibility, Explained with Official Links

GATE 2027 eligibility: third year or higher of any undergraduate degree, or a completed one, and no age limit. What the official IIT Madras brochure says, in plain language, with common cases worked through.

5 min read

GATE 2027 Exam Date and Schedule: Every Official Date So Far

The GATE 2027 exam date: 6 to 7, 13 to 14 and 20 to 21 February 2027, with exam cities on 4 January and results on 19 March. The official IIT Madras dates, and how to plan backwards from them.

5 min read

GATE 2027 Syllabus: Where to Find Your Branch's Official Syllabus

The GATE 2027 syllabus was revised, so use the 2027 PDF for your paper. Where IIT Madras publishes each one, the official section names for CS, EC, EE, ME and BT, and how to check a topic in a minute.

6 min read

A 90-Day GATE Study Plan You Can Actually Follow

A GATE study plan for the last 90 days: start on 8 November 2026 to finish on 5 February 2027, with hours split by the official GATE marks pattern and dated phases for learning, revision and mocks.

7 min read

How the GATE Application Process Works: Documents to Exam Day

The GATE application process, from the official brochure: the GOAPS portal, DigiLocker, documents and photo ID, payment, then city allotment, admit card and exam day. Registration timing and fees are on the official site.

7 min read

GATE CS Preparation: A Subject-by-Subject Study Order

A GATE CS preparation order built from the official 2027 syllabus: which of the ten sections to study first, which ones depend on each other, and a 17-week plan to the exam.

7 min read

GATE ECE Preparation: A Subject-by-Subject Study Order

A GATE ECE preparation order built from the official 2027 EC syllabus: which of the eight sections to study first, how they depend on each other, and a 17-week plan to the exam.

7 min read

The Last 30 Days Before GATE: A Revision Plan

GATE last month preparation, day by day: from 7 January to 5 February 2027, a revision pass, seven full-length papers with reviews, and a taper, plus how to turn mock mistakes into a plan.

6 min read

GATE Marking Scheme: MCQ, MSQ, NAT and Negative Marking

The GATE 2027 marking scheme: 1 and 2-mark questions, negative marking of 1/3 and 2/3 on wrong MCQs only, no partial marks in MSQ. A fully worked score and when guessing pays.

6 min read

Common Mistakes in GATE NAT Questions

GATE NAT questions carry no negative marking, so the marks you lose come from avoidable slips: radians, natural logs, units, early rounding and signs. Five worked examples of each mistake, with the right answer.

6 min read

GATE Preparation While Working Full Time

GATE preparation for working professionals: about 350 study hours at 20 a week before February 2027, how to split them by the official marks pattern, and what the GATE 2027 rules mean if you have a job.

6 min read

GATE Score vs Marks: How Your GATE Score Is Calculated

GATE score calculation, step by step: the official GATE 2027 formula that turns marks out of 100 into a score anchored at 350 and 900, the qualifying-mark rule, and a fully worked example.

6 min read

Network Theory Formulas to Know for GATE EC and EE

Network theory formulas for GATE EC and EE in one place: dividers, star-delta, first-order transients, RLC resonance and Q, complex power, two-port parameters and three-phase power, each with a worked number.

8 min read

PN Junction Diode for GATE: Concepts and Common Mistakes

The PN junction diode for GATE EC: built-in potential, depletion width and junction capacitance with a fully worked silicon example, and the mistakes that cost marks.

7 min read

Thevenin and Norton Theorems for GATE, with Solved Examples

Thevenin's theorem for GATE EC and EE: a two-source circuit and a bridge with a load to optimise, each worked two ways, plus maximum power transfer.

8 min read

How GATE Normalization Works Across Multiple Sessions

GATE papers held in more than one session are normalized before scoring. The official GATE 2027 formulas from IIT Madras, explained step by step with a worked example, including how normalized marks become your GATE score.

5 min read