• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 98 subscribers
  • Views 1205 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.

Issue with Keystone II IBIS model

suhas dk
Prodigy 110 points

Other Parts Discussed in Thread: 66AK2E05

I have downloaded the Keystone II (66AK2E02) IBIS model from TI website link (www.ti.com/.../toolssoftware) and We have checked  the IBIS model (without trace&via) for data signals, result is not good for IBIS model alone.

 The 66AK2E05/66AK2E02 processor IBIS model has skewed output by default, for various patterns of input bits. So the eye diagram of IBIS model alone (without channel) appears to be distorted. please refer the image

Can somebody please confirm this is the latest/correct IBIS model for processor (66AK2E05/66AK2E02).

Regards,

Suhas D K.

  • 0
    TI__Mastermind 43660 points

    Hello Suhas,

    Could you please explain your test setup like simulation tool, sequence pattern, bit rate, etc.,  ?

    I believe you have a simulation network with transmit buffer assigned with DDR3 data and a end termination to ground, right ?

    I checked similar setup at my side in Hyperlynx tool, but i do see a proper eye diagram as below (not distorted as yours). So please share your test scenario to reproduce at my side.

    Regards,

    Senthil

  • 0 in reply to Senthilkumar Srinivasan
    Prodigy 50 points

     Hi Senthil,
     
         We are using Ansys designer Tool for analysis and the simulation network with Transmitter buffer assigned  for DDR3L-1600MTs.
    We have checked with two different bit patterns,
    1. Random bit pattern (1000 bits)
    2. PRBS as source

    While checking IBIS with PRBS source as input patttern, we got a skewed eye as shown above. (for both DQ & Address using this processor IBIS)
    For the same setup with random bit patttern, eye  diagram does not have any skew for DQ,  but Address output have the same skew pattern even with random bit pattern.

    Please find the images below,


      


    Regards,

    Harini M.

  • 0 in reply to Harini Manoharan
    TI__Mastermind 43660 points
    Hello Harini,

    Here I do not have Ansys designer tool for simulation. However, i tried simulating this in Hyperlynx tool with PRBS for both data and address pins. But I do not see any skew that you mentioned above. Please refer the waveform that i attached in above post.

    I do not have option in Hyperlynx to simulate with random bit pattern mode.

    Have you tried any other IBIS model in your Ansys tool ?

    Regards,
    Senthil
  • 0 in reply to Senthilkumar Srinivasan
    Prodigy 50 points

    Hi Senthil,


     Yes, We were tried with many other IBIS models in the Ansys Designer, for those cases we got a good eye pattern (without skew).

    Earlier we used TI ARM4377 processor model using Ansys Designer. We dint get any issue with that model.


    While checking 66AK2E05/02 keystone II processor IBIS Model alone we get such issues (i.e) only with random bit pattern we get good eye, but with PRBS we get skewed eye. For Address pins, we get skewed eye for either case.

    Regards,

    Harini

  • 0 in reply to Harini Manoharan
    TI__Mastermind 43660 points
    Hello Harini,

    I will check on this issue with IBIS modelling team and get back to you.

    Regards,
    Senthil
  • 0 in reply to Senthilkumar Srinivasan
    TI__Mastermind 43660 points
    Hello Harini,

    We can’t support this since we do not have the Ansys tool with us. The models are normally only supported on the tools we have validated. Otherwise, our support is limited. If possible, please try with Hyperlynx tool and let me know.

    Regards,
    Senthil