Extra exam question E7H06
Subelement E7, PRACTICAL CIRCUITS· Group E7H
Which of these functions can be performed by a phase-locked loop?
- A.Wide-band AF and RF power amplification
- B.Frequency synthesis and FM demodulation (correct answer)
- C.Photovoltaic conversion and optical coupling
- D.Comparison of two digital input signals and digital pulse counting
WhyA phase-locked loop can perform frequency synthesis and FM demodulation. A phase-locked loop can perform frequency synthesis (generating a stable output at a multiple of a reference frequency) and FM demodulation (since the VCO control voltage needed to track a frequency-modulated input directly reproduces the original modulating audio), answer B. Wide-band power amplification, photovoltaic conversion, and simple digital pulse counting aren't functions a PLL is built to perform.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.