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LMX2572: Phase step increment? And minimum frequency step?

Aaron Jones
Prodigy 10 points

Part Number: LMX2572

Hello - 

Have scoured the data sheet and must be hidden because I'm missing it...two questions: 

1. How accurate is the phase adjustment?

2. What is the minimum frequency step?

End goal is to digital beamform with multiple channels and (1) trying to estimation calibration accuracy - would also like to (2) change frequency in small steps (10's of kHz). 

  • 0
    TI__Mastermind 32152 points

    Hi Aaoron, 
    It is pretty accurate overall. Are you asking if there is drift across temperature? Can you elaborate more? 

    Minimum frequency shift is as follow: 

    Thus smallest phase shift possible is as noted below using smallest mash seed and largest values for PLL_DEN & CH_DIV. 

    Regards, 

    Vicente 

  • 0
    Prodigy 10 points
    vicente flores prado said:
    is pretty accurate overall. Are you asking if there is drift across temperature? Can you elaborate more? 

    Hi Vincent - thank you for the response, very helpful - yes, that phase is accurate for our needs.  

    A bit more detail on the frequency generation - looking to generate a bunch (10-20) tones that are equally spaced in the 10's of kHz range.  For example, if we had for LMX's each would need to generate a tone that is say 20kHz apart, so 20,40, 60, 80, etc...  The questions is, can we generate tones (stable) with that level of precision? Not necessarily exactly 10kHz but equally spaced. 

    Does that make more sense? 

    Thanks

  • 0 in reply to Aaron Jones
    TI__Guru** 120710 points

    Hi Aaron,

    Were you talking about FM modulation?

    LMX2572 support FSK modulation, if your processor can continuously program LMX2572, then the output of LMX2572 is a FM signal. For details, please read below application note.

    www.ti.com/.../snaa309