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PRC EPLE: Electronics Engineering: Technical Core Tested in the PRC ECE Licensure Examination

PRC EPLE · Work through your exam, one topic at a time.

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Electronics Engineering: Technical Core Tested in the PRC ECE Licensure Examination

Scope of the electronics engineering domain

This domain samples the technical core of the PRC Electronics Engineer licensure examination: circuit analysis, electronic devices and amplifiers, digital systems, signals and communications, electromagnetics and transmission lines, control and instrumentation. Items are mostly computational, so credit depends on setting the model up correctly and tracking units and decibels; conceptual items test whether you know which approximation is legitimate (ideal op-amp, small-signal linearity, lossless line).

Core rules that drive most items

  • Linear circuits: superposition, Thevenin/Norton, node and mesh analysis; cross-check with power balance.
  • Devices: find the bias point first, then small-signal parameters (gm = IC/VT, with VT ≈ 26 mV at room temperature).
  • Decibels: 10 log10 for power, 20 log10 for voltage or current; cascaded stages add in dB.
  • Noise and links: Friis for cascaded noise figure, thermal noise density kT ≈ −174 dBm/Hz at 290 K, Shannon capacity C = B log2(1 + S/N).
  • Lines and antennas: Γ = (ZL − Z0)/(ZL + Z0); VSWR = (1 + |Γ|)/(1 − |Γ|); return loss = −20 log|Γ|; a quarter-wave section matches a real load when Z0′ = √(Z0ZL).
  • Digital: setup/hold margins and sampling above Nyquist (fs > 2·fmax).

Worked example

A 50 Ω lossless line feeds a 100 Ω resistive load. Γ = (100 − 50)/(100 + 50) = 0.333. VSWR = (1 + 0.333)/(1 − 0.333) = 2.0 - reporting 1.33 shows you added Γ instead of using the VSWR formula. Return loss = −20 log 0.333 = 9.5 dB. Power absorbed by the load = 1 − |Γ|² = 1 − 0.111 = 0.889, i.e. 88.9%; 11.1% is reflected. The sign of Γ is positive because ZL > Z0; a load below 50 Ω gives negative Γ but the same VSWR.

Traps that cost marks

  • Mixing power and voltage dB rules (a 2:1 voltage ratio is 6 dB, not 3 dB).
  • Using peak values where RMS is required for power.
  • Skipping prefix conversions (mW to W, pF to F) before substituting.
  • Applying ideal op-amp assumptions when finite gain or slew-rate limiting is stated.
  • Reporting |Γ| as VSWR, or a VSWR below 1.
  • Treating a line as lossless when attenuation per metre is given.