Question
What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital-to-analog converter, and a low-pass anti-alias filter?
Answer Options
- A) A direct digital synthesizer
- B) A hybrid synthesizer
- C) A phase-locked loop synthesizer
- D) A direct conversion synthesizer
Correct Answer: A
Explanation
Frequency synthesizers generate stable frequencies for radios. The Phase-Locked Loop (\text{PLL}) architecture is common, but another modern, highly flexible method generates the waveform mathematically in the digital domain.
The circuit described—using a phase accumulator, which tracks the phase of the output signal; a lookup table, which stores the voltage values of the desired waveform; a digital-to-analog converter (\text{DAC}), which converts the digital values to an analog waveform; and an anti-alias filter, which cleans the analog output—is the definition of a Direct Digital Synthesizer (\text{DDS}).
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