Master of Electrical Engineering Flashcards
7 cards from real ME or MEng Master of Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Master of Electrical Engineering flashcards as text
In digital communication, what is the Nyquist intersymbol interference (ISI)-free condition for a pulse shaping filter?
Answer: The pulse has zero crossings only at multiples of the symbol period T
A pulse is ISI-free if it equals 1 at t=0 and 0 at all other sampling instants t=nT, which requires zero crossings at all nonzero multiples of T.
A PID controller with derivative kick can be avoided by applying the derivative action to:
Answer: The process output y(t) only, not the reference r(t)
Applying derivative to y(t) instead of e(t) eliminates the 'derivative kick' that occurs when a step change in setpoint is introduced.
In electromagnetic compatibility (EMC), the concept of 'ground loops' causes interference primarily through:
Answer: Magnetically induced voltages in loops formed by multiple ground paths
Ground loops act as antenna loops that pick up time-varying magnetic flux, inducing a voltage V = -dΦ/dt = -jωBA in the loop.
For a first-order phase-locked loop (PLL), the closed-loop transfer function H(s) = ω_n/(s + ω_n) implies that the PLL:
Answer: Acts as a low-pass filter for phase deviations with bandwidth ω_n
H(s) = ω_n/(s+ω_n) is a low-pass transfer function; the PLL tracks slow phase changes (below ω_n) and attenuates fast phase noise.
Which semiconductor device structure is used in insulated-gate bipolar transistors (IGBTs) to combine high input impedance with low on-state voltage drop?
Answer: MOSFET channel in series with a PNP BJT collector-emitter path
An IGBT uses a MOSFET input stage (high impedance gate) to drive a PNP bipolar transistor output stage, combining MOS controllability with BJT low saturation voltage.
In signal processing, the short-time Fourier transform (STFT) is limited by the Heisenberg-Gabor uncertainty principle, which states:
Answer: Better time resolution requires worse frequency resolution and vice versa
The uncertainty principle Δt·Δf ≥ 1/(4π) means a shorter analysis window (better time resolution) broadens the frequency resolution and vice versa.
In the design of a microstrip antenna, what is the primary factor that determines the resonant frequency?
Answer: The patch length, which must be approximately λ_eff/2
A rectangular microstrip patch resonates when its length equals approximately half the effective wavelength λ_eff/2, where λ_eff accounts for the effective permittivity.