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LMH0397: LMH0397 Schematic Review

Nasser Mohammadi
Guru* 93670 points
Part Number: LMH0397

Greetings,

Please review this schematic and let us know your comments:

Best Regards, Gizem

  • TI__Guru* 93670 points

    Hi Gizem,

    We are reviewing this and will let you know within the next two days.

    Regards, Nasser

  • TI__Expert 5900 points

    Hi Gizem,

    Thank you for sending. I reviewed with my team and concluded that the schematic does not have any critical issues. Here are a few comments.

    • Capacitances on the supply are the correct values
    • Are the resistances on the single ended traces out of pins 18 and 19 (in0- and in0+) 50Ω? if so that is right.

    Best,

    Nick

  • Prodigy 10 points

    Hi Nasser,

    Thank you for your feedback. I will proceed to the layout stage, but I need an 8-layer stack up, can you help me? Do you have a stack up file for this kind of work or do you also use the LMH0397 material? Or what should I pay attention to when preparing the stack up? The recommended path thickness on the datasheet and eval board seems to be 10mil, can I draw a thinner path than this value?

    Best Regards, Gizem

  • in reply to gizem csk
    TI__Expert 5900 points

    Hi Gizem,

    Please contact your PCB manufacturer. The stack up should support a 75-ohm single ended trace and a 100-ohm differential trace. This is typically done with a layer 2 ground plane for the 100-ohm differential and a layer 3 ground plane for the single ended 75-ohm trace. 

    gizem csk said:
    Do you have a stack up file for this kind of work or do you also use the LMH0397 material?
    • I will check with Nasser and see if we can send you a schematic and layout of one of the LMH devices EVMs by email for your reference.
    gizem csk said:
    The recommended path thickness on the datasheet and eval board seems to be 10mil, can I draw a thinner path than this value?
    • For the 100-ohm differential traces the max recommended trace width is 8mil and for 75-ohm traces it can be 8 mil as minimum
    gizem csk said:
    Or what should I pay attention to when preparing the stack up?
    • Pay attention to the datasheet layout guidelines

    Best,

    Nick