• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 35 subscribers
  • Views 685 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Using SMPTE cable equalizers like the LMH0394 with Fibre Channel

Drake Dingeman
Prodigy 20 points

Other Parts Discussed in Thread: LMH0394, DS30EA101, DS15EA101, TLK4201EA, DS30BA101

Is there any reason that the cable equalizers like the LMH0394 would not work with Fibre Channel signals?

  • 0
    TI__Guru* 93570 points

    Hi Drake:

    SDI Equalizers like LMH0394 are designed to comply with SMPTE requirements. SMPTE specifies using certain scrambler and the data patterns are different from fiber channel. I believe one can use LMH0394 using fiber channel 8/10bit coded data pattern. However, LMH0394 has been designed for 800mV launch amplitude single ended  signal. Another option you may want to consider is DS30EA101 or DS5EA101 devices. These parts could be used in 100 ohm differential and 8/10bit coded data pattern.

    Regards,,nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 20 points

    I assume you meant DS15EA101.

    The DS30EA101 and DS15EA101 also seem to also require the 800mv p-p amplitude. The amplitude limitation I think can be handled by a flat input attenuator as the launch amplitude for Fibre Channel is 1700mv p-p. The tolerance for this 800mv is +/- 10% in the DS30EA101 data sheet. If the launched signal varies somewhat more than this, what is the consequence? If the cable has compensation built into it, what might this do? Since passive equalization is done by  attenuating the lower frequencies (high pass filters), I would think that the equalizer might respond to this in the same way as it would to shorter cable with a smaller launch amplitude. This makes me want to know how more how the adaptive part of the equalizer works. Is there any info on this anywhere?

    It looks like one of the ways around the launch amplitude problem is to use the non-adaptive, fixed eq devices like the tlk4201ea. The problem I would see with this is when a very short cable is used, the higher frequencies will be overemphasized. Has this effect been tested? Are there any devices of this type where the eq can be bypassed?

  • 0 in reply to Nasser Mohammadi
    TI__Mastermind 18501 points

    Nasser, can you please look into the follow up questions from Drake?

  • 0 in reply to Viktorija Cecil
    TI__Guru* 93570 points

    Hi Drake,

    What i had meant was to say you can use DS30BA101 on the Tx side and DS30EA101 on the receiving side. DS30BA101 delivers 800mV launch that DS30EA101 has been optimized or designed for. DS30EA101 data sheet spec is based on assuming 800mV +/- 10% launch amplitude.  Please let me know if this answered your question.

    Regards,,nasser