Signals and Systems MCQs 2026

Second-order underdamped system poles are

1. Areal and equal always✓
2. Bcomplex conjugate pair σ ± jωd✓
3. Cpurely imaginary without real part always✓
4. Don positive real axis for stability✓

Unit impulse δ(t) has Laplace transform

1. A0✓
2. B1/s✓
3. C1✓
4. Ds✓

Partial fraction expansion aids

1. AK-map grouping of minterms✓
2. BBJT beta measurement only✓
3. Cenergy meter creep adjustment only✓
4. Dinverse Laplace transform of rational F(s)✓

Laplace transform of derivative df/dt is

1. AF(s)/s only without initial condition✓
2. BsF(s) − f(0−)✓
3. Cf(0−) only without sF(s)✓
4. D1/(s + jω) only✓

Region of convergence (ROC) of Laplace transform specifies

1. Avalues of s for which the defining integral converges✓
2. Bonly time-domain period T✓
3. Conly logic gate fan-out✓
4. Donly diode forward voltage✓

Pole of H(s) at s = −a corresponds to

1. Asinusoid without decay always✓
2. Bconstant DC without dynamics✓
3. Cexponential mode e^(−at) in impulse response✓
4. Ddigital counter state only✓

Transfer function H(s) of LTI system is ratio of

1. Atime-domain convolution only without transform✓
2. BFourier series coefficients only✓
3. CK-map product terms only✓
4. DLaplace transform of output to input with zero initial conditions✓

Final value theorem gives steady-state f(∞) from F(s) as

1. Alimit of sF(s) as s approaches infinity✓
2. Blimit of sF(s) as s approaches 0✓
3. Cpole at origin count only✓
4. Dinverse transform without limits✓

Initial value theorem gives f(0+) from F(s) as

1. Alimit of F(s) as s approaches 0 only✓
2. Blimit of sF(s) as s approaches infinity✓
3. Cderivative of F(s) at s=0 only✓
4. Dintegral of F(s) without limit✓

Laplace transform of e^(−at) u(t) is

1. A1/(s − a) without sign✓
2. Bs/(s + a)✓
3. C1/(s + a)✓
4. Da/s only✓

Laplace transform of unit step u(t) is

1. A1/s✓
2. Bs✓
3. C1/s² only✓
4. De^(−s) without 1/s✓

Laplace transform converts time-domain function to

1. Aonly discrete frequency bins without s✓
2. Bcomplex frequency domain s = σ + jω✓
3. Cdigital logic states only✓
4. Dspatial domain only✓

Distortion analysis of amplifiers often uses

1. Aonly K-map minimization✓
2. Bonly CT knee-point voltage✓
3. Charmonic amplitudes from Fourier decomposition of output✓
4. Donly Johnson counter sequence✓

RMS value of periodic signal can be found from Fourier coefficients using

1. Asum of squares of harmonic amplitudes (Parseval)✓
2. Bonly peak value divided by π✓
3. Conly fundamental amplitude without harmonics✓
4. Donly DC term squared always without AC terms✓

Frequency shifting property of Fourier transform multiplies time signal by e^(jω0t) to

1. Ascale time axis only✓
2. Binvert spectrum about origin only✓
3. Celiminate all negative frequencies without analytic signal✓
4. Dshift spectrum by ω0✓

Fourier transform of aperiodic signal yields

1. Acontinuous frequency spectrum✓
2. Bdiscrete harmonics only like periodic case✓
3. Csingle coefficient without frequency spread✓
4. DLaplace transform identical without jω✓

Discrete-time convolution sum is

1. Aproduct x[n]h[n] only✓
2. BFourier series of continuous signal✓
3. Cy[n] = Σ x[k] h[n − k]✓
4. Donly logic OR of bits✓

Causal system impulse response is

1. Azero for t < 0✓
2. Bnonzero for all negative time always✓
3. Cundefined without Laplace✓
4. Dequal to step input always✓

Convolution with unit impulse δ(t) returns

1. Athe original signal f(t)✓
2. Bzero always✓
3. Cderivative of f(t) only✓
4. Dintegral of f(t) only✓

Graphical convolution involves

1. Aonly multiplying magnitudes at t=0✓
2. Bflipping, shifting and integrating product of overlapping signals✓
3. Conly Laplace partial fractions without time view✓
4. Donly flip-flop clock edges✓

Convolution is commutative meaning

1. Af * g = −g * f always✓
2. Bf * g = g * f✓
3. Cconvolution never commutes✓
4. Donly for digital signals not analog✓

Output of LTI system is convolution of input with

1. Astep response only without convolution✓
2. Bonly DC gain scalar✓
3. Cimpulse response h(t)✓
4. Donly noise spectrum✓

Convolution in time domain corresponds to multiplication in

1. AK-map domain only✓
2. Blogic truth table domain✓
3. CLaplace domain (and Fourier domain with convergence)✓
4. Donly time-domain subtraction✓

Convolution of two signals f(t) and g(t) is defined as

1. Aintegral of f(τ) g(t − τ) dτ✓
2. Bproduct f(t)g(t) only without integration✓
3. Csum of Fourier coefficients only✓
4. DXOR of digital bit sequences✓

Laplace domain multiplication corresponds to

1. Atime-domain convolution✓
2. Btime-domain addition only✓
3. CFourier series division✓
4. Dlogic AND in gate network✓

Sampling period T equals

1. Afs✓
2. B2πfs✓
3. Cfs squared✓
4. D1/fs✓

Effective bits of ADC measure

1. Aonly DC offset error without noise✓
2. Bonly full-scale voltage without noise✓
3. Conly clock jitter without amplitude error✓
4. Dresolution equivalent to ideal ADC achieving same SNR✓

Zero-order hold in digital control introduces

1. Ainfinite bandwidth without distortion✓
2. Belimination of all phase delay✓
3. Cfrequency response sinc-like droop and phase lag✓
4. Donly improves Nyquist margin unconditionally✓

Undersampling of bandpass signal can still avoid aliasing if

1. Ano filter is used ever✓
2. Bsignal is not bandlimited✓
3. Conly DC is present✓
4. Dsignal occupies a band within an integer slot of fs✓

Nyquist rate for signal bandlimited to B Hz is

1. A2B samples per second✓
2. BB/2 samples per second✓
3. C4B always without exception✓
4. D1/B samples per second✓

Reconstruction of bandlimited signal from samples uses

1. Adifferentiator only✓
2. Bfull-wave rectifier only✓
3. CJK flip-flop toggle only✓
4. Dideal low-pass filter (sinc interpolation)✓

Signal-to-quantization-noise ratio improves approximately by

1. A0 dB per bit always✓
2. B20 dB per bit always✓
3. Cdecreases with more bits✓
4. D6 dB per bit of ADC resolution✓

Quantization noise in uniform quantizer is approximately

1. Aalways zero without error✓
2. Bsinusoidal without relation to LSB✓
3. Cuniformly distributed over one LSB✓
4. DGaussian with infinite variance always✓

Sample-and-hold circuit maintains

1. Adigital count indefinitely without drift✓
2. Banalog value at sampling instant for ADC conversion✓
3. Chigh-frequency amplification only✓
4. Drectified DC without sampling✓

Anti-aliasing filter before ADC is

1. Ahigh-pass filter only✓
2. Blow-pass filter limiting bandwidth below Nyquist limit✓
3. Cband-stop at DC only✓
4. Dlogic gate with hysteresis✓

Aliasing occurs when

1. Asampling rate is infinitely high always✓
2. Banti-alias filter is perfect without limit✓
3. Csignal contains frequencies above fs/2 and appears as lower frequency✓
4. Donly DC signals are sampled✓

Nyquist sampling theorem requires sampling frequency at least

1. Aequal to lowest frequency only✓
2. Bhalf the highest frequency✓
3. Ctwice the highest frequency component in the signal✓
4. Dten times any harmonic without bound✓

Convolution integral limits for causal f and g starting at zero extend

1. Afrom −∞ to ∞ always without limit change✓
2. Bfrom 0 to t✓
3. Cfrom t to ∞ only✓
4. Donly single point τ = t✓

System stability from impulse response requires for BIBO

1. Aabsolutely integrable h(t) for continuous LTI✓
2. Bh(t) unbounded always for stability✓
3. Conly pole at origin without decay✓
4. Donly digital systems without integration✓

Circular convolution differs from linear convolution when

1. ADFT length causes time-domain aliasing of tails✓
2. Bsignals are aperiodic without wrap✓
3. Conly continuous-time applies✓
4. Dinputs are impulses only✓

Overlap-add method is used for

1. AK-map minimization only✓
2. BCT saturation testing only✓
3. Conly analog differentiation✓
4. Defficient block convolution of long sequences✓

Gibbs phenomenon refers to

1. Aovershoot near discontinuities in truncated Fourier series reconstruction✓
2. BDC drift in integrator op-amp✓
3. Caliasing during undersampling✓
4. Dmetastability in flip-flop✓

Duty cycle change in rectangular pulse train affects

1. Aonly DC without harmonics✓
2. Bmagnitudes of harmonic components in the spectrum✓
3. Conly fundamental without any harmonics change✓
4. DLaplace region of convergence only✓

Complex exponential Fourier coefficient Cn equals

1. Amaximum peak of f(t) only✓
2. Bderivative of f(t) at t=0 only✓
3. CLaplace transform at s=0 only✓
4. Daverage value of f(t) e^(−jnω0t) over one period✓

Line spectrum of periodic signal shows

1. Acontinuous spectrum only without lines✓
2. Bdiscrete frequencies at harmonics with corresponding amplitudes✓
3. Conly DC without harmonics always✓
4. Dphase margin on Bode plot✓

Parseval theorem relates

1. ALaplace poles to zeros only✓
2. Baverage power in time domain to sum of squared Fourier coefficients✓
3. Cconvolution to sampling only✓
4. Ddiode PIV to ripple factor✓

Trigonometric Fourier series of odd function contains

1. Aonly cosine terms✓
2. Bonly DC component✓
3. Conly sine terms✓
4. Donly even harmonics of cosine✓

Trigonometric Fourier series of even function contains

1. Aonly sine terms✓
2. Bonly odd harmonics without DC ever✓
3. Cexponentials with negative real parts only✓
4. Donly cosine terms (and possibly DC)✓

Fundamental frequency of Fourier series is

1. Atwice the highest harmonic always✓
2. Balways 50 Hz without exception✓
3. Czero for all non-sinusoidal waves✓
4. Dreciprocal of the period of the waveform✓

Fourier series represents a periodic signal as

1. Asum of sinusoids at harmonics of fundamental frequency✓
2. Bsingle exponential decay only✓
3. CDC step without harmonics always✓
4. Drandom noise without structure✓

Circular convolution differs from linear convolution when

1. ADFT length causes time-domain aliasing of tails✓
2. Bsignals are aperiodic without wrap✓
3. Conly continuous-time applies✓
4. Dinputs are impulses only✓

System stability from impulse response requires for BIBO

1. Aabsolutely integrable h(t) for continuous LTI✓
2. Bh(t) unbounded always for stability✓
3. Conly pole at origin without decay✓
4. Donly digital systems without integration✓