LMX2595EVM: LMX2595EVM

Prodigy 10 points

Replies: 2

Views: 57

Part Number: LMX2595EVM

We understand the methods to improve the close in spurs.  Our problem is related to using the MASH_SEED and the intermittency we are experiencing with it.

 

With the MASH_SEED enabled, and a given MASH_SEED number, we get good spur performance.  However, if we select and unselect the “MASH_RESET_N”, sometimes the spur performance for the unchanged MASH-SEED changes to something undesirable.  It is not repeatable.  All this using the LMX2595EVM evaluation board and software.

 

We see the same effect on the PLL in our actual circuit.  At a given frequency, using a given MASH_SEED, sometime we get the desired spur performance but sometimes we do not, as if the MASH_SEED function is not repeating.

Reference frequency in is 100MHz. Phase comparison Frequency is 200 MHz Output Frequency is 7502.5 MHz. We see this at other frequencies as well.

2 Replies

  • Hello John,

    This ticket has been assigned. We'll get back to you soon.

    Regards,
    Hao

  • In reply to Hao Z:

    Hi John,

    Right, MASH_SEED is not repeatable, not consistent and not non-volatile, if you use it to reduce spurs. 

    What is your fractional DEN and MASH order?