The output frequency, fout, of the DDS waveform is a function of the system clock frequency, fclk, the phase width (that is, the number of bits (Bθ(n)) in the phase accumulator), and the phase increment value, Δθ. The output frequency in Hertz is defined by:
For example, if the DDS parameters are:
- fclk = 120 MHz
- BΘ(n) = 10
- ΔΘ = 12 (decimal)
Then the output frequency is calculated as follows:
The phase increment value Δθ required to generate an output frequency fout Hz is:
If the DDS core is time-division multiplexed to do multiple channels, the effective clock frequency per channel is reduced. For C channels, the phase increment required is:
