• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 48 subscribers
  • Views 610 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DAC38J84 / maximum output frequency

Toshiyuki
Mastermind 7075 points

Other Parts Discussed in Thread: DAC38J84

Hi,

Our customer are considering their system as below.

・Center Frequency=2GHz

・bandwidth=24,32,56MHz

Please let me know if DAC38J84 could be generated these output frequency.

Best Regards,

Kato

  • 0
    TI__Genius 17470 points

    Hi Kato,

    In order to output a signal at 2 GHz, the image in the 2nd Nyquist zone would have to be used. The DAC38J84 is designed to be a 1st Nyquist zone DAC, but a signal could be output in the second Nyquist zone. The issue is that the sine(x)/x response of the DAC will attenuate the signal and thus limit the performance. So the simple answer is that yes, the DAC can output this frequency, however the performance will be degraded due to the attenuation of the signal.

    Regards,
    Matt Guibord

  • 0 in reply to Matt Guibord
    Mastermind 7075 points

    Matt -san,

    Thank your for the reply.

    I have additional questions.

    Please let me know how much the signal would be attenuated at 2GHz.

    And what is the output frequency from 1.5GHz to 2.5GHz to  get the best performance?

    Best Regards,

    Kato

     

  • 0 in reply to Toshiyuki
    Mastermind 7075 points

    Matt - san,

    What is the frequency from 1.5GHz to 2.5GHz to get the best performance?

    And  could we generate the signal pattern[1.5～2.5GHz] to evaluate DAC38J84 by TSW1400 Pattern Generators?

    Best Regards,

    Kato

     

  • 0 in reply to Toshiyuki
    TI__Genius 17470 points

    Hi Kato-san,

    Are you referring to the sampling rate or the output frequency? Generally you'll want to avoid HD2 and HD3. If the center frequency is flexible, then lower is better. The avoid HD2 and HD3 while running at 2.5 GSPS, the center frequency should be kept below 1600 MHz. There may be clock mixing spurs that should be avoided as well.

    To output a signal in the 2nd Nyquist zone, a signal in the first Nyquist zone should be created such that Fs - Fsig is the desired frequency. For instance, to output 2 GHz while running at 2.5 GSPS, you should generate a signal at 500 MHz.

    Regards,
    Matt Guibord