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SN65DPHY440SS: How do I connect the S-Parameter pins in simulation

Zach Stokes
Prodigy 65 points
Part Number: SN65DPHY440SS


I am simulating a 4 lane MIPI bus, trying to generate Eye diagrams for each pair.

I have created an S-Parameter block with the 10 ports of input (5 diff pairs) and 10 ports of output (same 5 diff pairs, at the other end of my transmission path).

I'm using Ansys Electronics Desktop to simulate, but don't know how to wire my positive and negative signals into the block representing the RX PHY of this part.  Other Forum answers have specified that ports 1-5 represent the differential reflection/loss of DA0, 1, 2, etc, and ports 6-10 model the common mode behavior.

My question is: How do I connect my 10 wires to the RX PHY's 10 ports to accurately model how the PHY's presence in my circuit will affect signal integrity.

  • 0
    TI__Mastermind 20696 points

    Hi Zach, 

    You would want to create a differential pair via Ansys on the pair and connect the pair to the S-parameter port 1-5 for each differential pair. 

    Please let me know if this works. 

    Best,
    J

  • 0 in reply to J
    Prodigy 65 points

    I assigned the 2 pins of each of my pairs to be diff pairs when I created the S-Parameter model of my transmission path, but the resulting block still has separate ports for positive and negative.  So I have 2 ports on my model that I want to wire to 1 port on the model from y'all, and I don't know how to do that.  Are you saying I did something wrong while making the model?  I'm new to analog simulation, so if that's the case I wouldn't be surprised, I just want to make sure I'm working in the right direction.

  • 0 in reply to Zach Stokes
    TI__Mastermind 20696 points

    Hi Zach, 

    I checked in internally and it turns out this s parameter model is meant for return loss measurement and nothing else. So, running a simulation with this file will not yield any good data. 

    We have HSPICE model for this part you can use, but we cannot provide further support on this because we do not have license on HSPICE anymore. 

    5340.dphy440_hspice.tar.gz

    I apologize for the inconvenience this has caused. 

    Best,
    J

  • 0 in reply to J
    Prodigy 65 points

    My goal here is actually to calculate return loss, not to simulate actual function.  I just need the correct source and sink buffer behaviors so my signals act like they will in system purely on the transmission lines, not passing through the chip from RX to TX.

  • 0 in reply to Zach Stokes
    TI__Mastermind 20696 points

    Hi Zach, 

    I see. 

    So, I got information that these are the port definitions:
    Port 1 to Port 5 are differential ports for DA0 to DA3, e.g, S11 is the diff R/L for DA0P/DA0N, S22 is the diff R/L for DA1P/DA1N, ….
    Port 6 to Port 10 are CM ports for DA0 to DA3, e.g, S66 is the CM R/L for DA0P/DA0N, S77 is the CM R/L for DA1P/DA1N, ….

    So, to simulate differential return loss on diff DA0P/DA0N, you will have to do S1111, S2222, etc. 

    Unfortunately, because this measurement was done as a pair, there is no way to connect each pin of the differential pair, but to simulate the entire differential pair. 

    Best,
    J