Question
What information is contained in the lookup table of a direct digital synthesizer (DDS)?
Answer Options
- A) The phase relationship between a reference oscillator and the output waveform
- B) Amplitude values that represent the desired waveform
- C) The phase relationship between a voltage-controlled oscillator and the output waveform
- D) Frequently used receiver and transmitter frequencies
Correct Answer: B
Explanation
A Direct Digital Synthesizer (DDS) generates a continuous analog waveform (usually a sine wave) entirely from digital data. To do this, the circuit requires a precise map of what the waveform should look like over one complete cycle.
The lookup table in a DDS contains pre-calculated digital amplitude values that represent the desired waveform (typically a sine wave). The DDS phase accumulator cycles through these values, feeding them sequentially to the digital-to-analog converter (DAC), which then reconstructs the smooth analog output signal at the programmed frequency.
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