LMX2592: LMX2592 Walking spurs

Coney

Prodigy 80 points

Part Number: LMX2592

Hi support,

I'm working on with LMX2592 . I am seeing a phenomenon where there is a spur that goes across the spectrum over and over again (a walking spur). The denominator has great impact on the Spus.Is there any suggestion to solve it?

The PSA is max hold to capture the walking sours. I'm using the LMX2592 EVM

over 7 years ago

0 Brian Wang over 7 years ago

TI__Expert 8505 points

Hi,

Can you provide the software settings? If you are using TICS Pro, it can save as a ".tcs" file. This does seem like something related to the fractional setting. Also try changing the PFD_DLY, and MASH_ORDER. Does that make a difference?

regards,

Brian Wang

0 Coney over 7 years ago in reply to Brian Wang

Prodigy 80 points

Hi,

Thank you for your reply. Here is my ".tcs" file. I think you may get the same conclusion.

LMX2592_Walking_spurs.zip

0 Brian Wang over 7 years ago in reply to Coney

TI__Expert 8505 points

Hi,

I tried this in lab and see it too. It is because the input path has some violations, you have 100MHz OSCin then div-by-5 then mult-by-4, those violate the frequency the multiplier can be used at. If those are changed to acceptable range, it would be stable.

Regards,

Brian Wang

0 Coney over 7 years ago in reply to Brian Wang

Prodigy 80 points

Hi,
I'm sorry for my problem, but if the fpd is 100MHz, and LMX2592 is in Fractional mode with the same other settings. I can also see the spurs. Have you try it? I need LMX2592 in my system and the spurs arise.I don't know how to solve it now.

Clock & timing

Clock & timing forum

LMX2592: LMX2592 Walking spurs

Hi support,

I'm working on with LMX2592 . I am seeing a phenomenon where there is a spur that goes across the spectrum over and over again (a walking spur). The denominator has great impact on the Spus.Is there any suggestion to solve it?

The PSA is max hold to capture the walking sours. I'm using the LMX2592 EVM