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TMUX1309: S parameter model of TMUX1309

Wenting Wu
Intellectual 2190 points
Part Number: TMUX1309
Other Parts Discussed in Thread: TMUX1574, SN3257-Q1

Hello expert, 

  • May i ask for the S-parameter model of TMUX1309?
  • Do you have the specific test waveform for TMUX1309? The transient response waveform is preferred.
  • Input S1A, rising edge 0.7ns, falling edge 20ns, height ~100mV signals. Other channels do not input signals.
    The strobe strobes to S2A can be tested for the following signals.
    You can see the crosstalk is very obvious. When the signal is large, it is shown in the figure below. There are two peaks. May I ask why there are two peaks?

  • When the signal at the input S1A is reduced, the crosstalk amplitude is reduced and the waveform changes to the following waveform. the two summits converge.

Best regards,

wenting  

  • 0
    TI__Intellectual 2190 points

    Sorry to post the duplicated pictures. The 1st picture should be shown as the following.

  • +1 in reply to Wenting Wu
    TI__Genius 10552 points

    Hi Wenting,

    Unfortunately, we don't have an S-Parameter model for this device. Perhaps we can reach a resolution in a different way. Is there a schematic that you can provide here? Is the frequency through the switch ~300-400MHz?

    Some initial thoughts on reducing crosstalk would be to increase your resistive load on the output - this will reduce the total current draw during switching events and can help reduce the amount of crosstalk seen.

    If crosstalk is a major concern for their application, I would also recommend that they ensure there is ground plane between the output traces for this device to provide maximum signal isolation and to avoid running those lines in parallel (or at least not directly next to each other). 

    Additionally, with respect to bandwidth, you could be seeing some harmonics. The bandwidth for a square wave needs to be approached differently than that of a sine wave. When picking a device, you'll need to consider these harmonics of the square wave. A square wave is comprised of many sine wave components. In this case, we'd be looking at the 5th harmonic (5x the fundamental frequency; for example 10MHz x 5 = 50MHz). So just making sure this isn't a 300MHz square wave going through the device. 

    Regards,

    Alex

     

  • 0 in reply to Alex Vish
    TI__Intellectual 2190 points

    Hello Alex,

    It not easy to add output load, because the customer connects it to amplifier. If add output resistor, it will reduce signal amplitude.

    But the customer will also try to see it can reduce or not.

    The customer thinks output signal not need add GND, because this distance is very big. But input signal not easy add GND between different input channels.

     

    As we said the input waveform is not a square wave, you can think waveform is 0.7ns rise time, 20ns fall time  a signal wave. Not continue.

    So this have some frequency high than 500Mhz.

    May I ask why there are 2 peaks caused by this high frequency?

     

     Best regards,

    wenting 

  • 0 in reply to Wenting Wu
    TI__Genius 10552 points

    Hi Wenting,

    To clarify, are you saying your signal is ~500MHz? If so, this is not advised. Running the TMUX1309 at its maximum rated frequency will exaggerate cross talk effects

    If you need to pass a 500MHz signal through the device, I suggest using something with more bandwidth since we recommend using a device with 1.5X the bandwidth of your highest frequency signal if it's a continuous signal. Unfortunately, for a 4:1 this is our highest bandwidth part. If a higher channel count 2:1 works for your application, then I recommend going with the TMUX1574 as you will no longer have this crosstalk issue due to this devices 2GHz bandwidth. 

    Regards,

    Alex

  • 0 in reply to Alex Vish
    TI__Intellectual 2190 points

    Hello Alex,

    It's an automotive application. Will TMUX1574 have a automotive version or are there other automotive devices promoted?

  • 0 in reply to Wenting Wu
    TI__Genius 10552 points

    Hi Wenting,

    I wasn't aware this was for for automotive! In that case, I'd suggest the SN3257-Q1. It's our highest bandwidth automotive rated device. 

    Is there anything else I can do for you here?

    Regards,

    Alex