Sub 1kHz Sinewave generation

I am interested in generating a sine waveform in the sub 1kHz range. Frequency accuracy is a critical parameter, is there a DDS that would be recommended? Or should another approach be considered.

Thanks.

  • Hi,

    The DDS is capable of generating sine waveform in the sub 1kHz range. The output frequency of the DDS is controlled by the frequency tuning word (FTW) that is given by the formula below.

    Since the FTW is an integer, the generated output frequency will be in the range of the desired frequency ± 1/2^n. But absolute frequency accuracy can still be achieved by adjusting the DAC system clock (fsysclk).

    For an example of your desired frequency of 1 kHz and a system clock of 1 GHz, using the AD9910 with tuning word (N) of 32 would have an output frequency of 0.999996 kHz. On the other hand, the AD9912 with N of 48 would have an output frequency of 1.000000001 kHz. If this frequency accuracy is already acceptable, then adjusting the system clock will not be needed.

    Here is the selection table for all the DDS which includes the tuning word width for each part: https://www.analog.com/en/parametricsearch/11018

    Best regards,

    Mark

  • A follow-on to Mark's response:

    ADI also offers DDSs with a programmable modulus feature. Programmable modulus allows for output frequencies not achievable with "standard" DDS architectures. For example, in Mark's response, given an 1GHz system clock the DDS could not generate exactly 1kHz. Programmable modulus, on the other hand yields precisely 1kHz.

    The DDSs supporting programmable modulus:

    • AD9913
    • AD9914
    • AD9915