Which of the following are basic components of a sine wave oscillator?
An amplifier and a divider
A frequency multiplier and a mixer
A circulator and a filter operating in a feed-forward loop
A filter and an amplifier operating in a feedback loop✓Bonne réponse
Explication
Sustained oscillation needs a loop with at least unity gain and in-phase feedback at one frequency; the amplifier supplies the gain and the frequency-selective filter or tank ensures that only the desired frequency comes back in phase. Dividers, multipliers and mixers move frequencies around but do not by themselves sustain oscillation.