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TMUX1136: solution select

Denny Huang
Expert 7170 points
Part Number: TMUX1136
Other Parts Discussed in Thread: TMUX1108, , TMUX136

Dear team 

Dose TI have suitable analog switch which could be use to switch the GPON/XGSPON RX (APD-TIA) signal? Could you help to recommend solution?

Many thanks

Denny

  • 0
    TI__Mastermind 26868 points

    Hey Denny,

    I'm not very familiar with the APD-TIA signals. What are the frequency and voltage ranges here? I'm seeing a common mode 1.9V but what are the max and min voltages that will actually be seen?

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    TI__Expert 7170 points

    Hi Rami

    Basically, the Avalanche photodiode (APD) converts the received light into signal current.

    Through the TIA, it transfer the current signal to voltage signal.

    At low sensitivity case (-28dBm), the level of transferred voltage is very low (~10 mV).

    Also, the analog signal are working in 100 ohm differential mode.

    We do not switch the analog switch frequently. Actually, we just switch once for GPON/XGSPON operation to determine path.

    Dose TI have suitable solution for this application?

    Many thanks

    Denny

  • 0 in reply to Denny Huang
    TI__Mastermind 26868 points

    Hey Denny, 

    This should be fine. I'd recommend some guarding though on the traces to ensure that the leakage is minimized to reduce measurement errors since you're dealing with such a low voltage.

    Here's a good app note on this : 

    Guarding in Multiplexer Applications

    Table 3-2 may be of some interest too as you'll see TMUX1108 and the offset error listed in there. The TMUX1108 is in the same TMUX11xx family as the TMUX1136 so you can expect to see to close to this, given proper routing practices for this precision application.

    Hope this helps!
    Rami

  • 0 in reply to Rami Mooti1
    TI__Expert 7170 points

    Hi Rami

    TMUX136 has 6.1GHz bandwidth (-3 dB).

    However, the reply from the APD-TIA supplier is as follows.

    Could you help to suggest a better part from TI?

     

    -----

    The S21 curve is not smooth with some dips at ~3GHz.

    The 10G TIA output BW is typical about 6GHz, together with this bandwidth limiting switch will further attenuate the signal.

    It will be good you can choose switch with >7.5GHz BW, and smooth S21 response.

    Many thanks

    Denny

  • 0 in reply to Denny Huang
    TI__Mastermind 26868 points

    Hey Denny,

    We won't have a device that can support bandwidths that high. I'm going to loop in our high speed signal chain team to see if they have a solution.

    Thanks,
    Rami