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HMC7044 OSCOUT phase noise

Category: Datasheet/Specs
Product Number: HMC7044


I am interested in using the OSCOUT1 or OSCOUT2 pins of an HMC7044 as the input to another PLL. The other PLL needs a high quality clock source and I have a target SSB phase noise mask to meet. Is any OSCOUT SSB phase noise information available please?

Thank you in advance.


  • Hi Andy, 

    We don't have additive noise measurement for OSCOUT buffers. 

    However, I took some measurements in the past.

    The noise floor of HMC7044’s OSCOUT buffer is around -155dBc/Hz at 125MHz.  I added a measurement to show phase noises of a) SMA100B signal generator output (Blue) vs b) HMC7044 OSCOUT Buffer output when OSCIN is fed with SMA100B (Black).   

    Another measurement compares HMC7044 OSCOUT performance when OSCIN is fed by a CVHD-950 crystal oscillator. 

    Another measurement shows the performance of ADF4371 when the reference is fed by the OSCOUT buffer vs CVHD-950. This might be more close to your application.  

    PN measurement of ADF4371 (green: Reference is CVHD-950, blue: OSCOUT from HMC7044 while OSCIN is CVHD-950)



  • That's very helpful, thank you. Are you able to tell me what driver mode you were using for the tests please? Is it the default, which I think is CML without internal resistors?

  • Hi Andy, 

    I used the LVPECL output buffer type. CML also performs similarly. For CML measurements, I have used the default configuration which internal 100 is enabled.