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LMX2571-EP: looking for a synthesizer with setpoint 50kHz to 2MHz

Stefan Lintner
Expert 4665 points
Part Number: LMX2571-EP
Other Parts Discussed in Thread: CDCE6214-Q1, CDCE6214

Hi Team,

I am looking for a synthesizer with below specs

  • Setpoint from 50 kHz to 2 MHz
  • Jitter over the entire range less than 100 ps, nice to have would be even less than 10 ps.
  • Resolution of the period should be 1.6 ns, nice to have would be 1 ns.

do we have a solution for this?

BR,
Stefan

  • 0
    TI__Guru* 86030 points

    Hi Stefan,

    What does setpoint mean? The integration bandwidth of jitter or the output frequency of the synthesizer?

    Put it this way:

    1. What is the output frequency

    2. What is the input frequency

    3. phase noise or jitter requirement

    3. must be -EP grade?

  • 0 in reply to Noel Fung
    TI__Expert 4665 points

    Hi Noel,

    1. What is the output frequency
      1. The output frequency is 50 kHz to 2 MHz
    2. What is the input frequency        
      1. The input frequency is free to choose.
    3. phase noise or jitter requirement
      1. The jitter requirement is less than 100 ps

     

    Do we have a solution with programmable clock output with the specs. mentioned ?

    BR,
    Stefan

  • +1 in reply to Stefan Lintner
    TI__Guru* 86030 points

    Hi Stefan,

    Since the output frequency is quite low, synthesizer cannot support.

    You can try CDCE6214-Q1, it is a clock generator, output frequency is configurable between 24kHz and 328MHz.

  • 0 in reply to Noel Fung
    TI__Expert 4665 points

    Hi Noel,

    thank you for suggesting CDCE6214-Q1!

    One question from customer side:

    • How does the jitter of the output clock depend on the clock signal that I supply to the CDCE6214? If I take an oscillator with a jitter specification of 5 ps, will the CDCE6214 still achieve its specifications? Or is it somehow added to each other?

    BR,
    Stefan

  • 0 in reply to Stefan Lintner
    TI__Guru* 86030 points

    Hi Stefan,

    Any PLL-based clock generator or synthesizer requires good input clock. Jitter is not a good parameter to represent the quality of the input clock. A phase noise plot of the input clock helps us determine its quality. In general, we care the phase noise of the input clock up to 10kHz offset.

  • 0 in reply to Noel Fung
    TI__Expert 4665 points

    Hi Noel,

    Aren’t phase jitter and phase noise the same thing, but represented in time and frequency domain, respectively? Most datasheets only specify the phase jitter with one number, and mention the frequency band (mostly starting from 12 kHz, to, e.g., 5 MHz).

    So I should find out this number for 10 kHz and lower? And what should the value be? It is not entirely clear to me yet how I can confidently say that the input clock I choose is good enough to achieve the specifications mentioned in the datasheet. Is the following clock good enough?

    ECS_2520MV-1314080.pdf (mouser.com)

    BR,
    Stefan

  • +1 in reply to Stefan Lintner
    TI__Guru* 86030 points

    Hi Stefan,

    General purpose XO usually don't include phase noise spec in the datasheet. Customer can request the XO vendor for a phase noise plot.

    Some XO are designed for low phase noise application, their datasheet will contain phase noise information. For example, https://www.crystek.com/home/oscillator/clock.aspx.