6 Replies Latest reply on Oct 9, 2014 12:20 PM by agxinmj

    Regarding terminator wizard

    ankan

      Hello everybody

       

      This  question doesn't relate with  hyperlynx 8.0 but with 7.7.Mostly we have  done termination value  calculations in Boardsim(post layout) using  terminator wizard but not in  linesim(i.e in pre layout).

       

      Could  you please explain what are the steps to follow if i want to simulate  for the termination values in terminator wizard using linesim.

       

      You can make it in brief if you want

       

      will be obliged if you could do so.

       

      Regards

      Ankan

        • 1. Re: Regarding terminator wizard
          Steve_McKinney

          For LineSim, draw your schematic with driver, receiver, transmissions and terminations that you're using.  Lets say it's a series resistor termination, so you have something like this:

           

          series_term.png

           

          You can just leave the value at 0 Ohms, run the terminator wizard like you normally would and then apply the value to the termination.  The terminator wizard may not be able to handle all your complex topologies, but it should be able to handle a lot of them. 

           

          -Steve

          1 of 1 people found this helpful
          • 2. Re: Regarding terminator wizard
            ankan

            Hi Steve


            Thanks for your reply.I got your point ,however still have some doubts in my mind if you can clear that.


            1)The transmission line parameters like the impedance and rise time values are loaded when the stack up is enetered as we can also edit the Tx line parameters like (TL1 And TL2 in your case),but how can we know the exact impedances and timing values for these Tx lines?


            2)Can we load the IBIS models for the driver and receivers and can take the respective pins into account while simulating through linesim?


            3)In case of differential Tx lines, can we simulate and find the differential termination resistances in linesim ?


            I think this questionairre has become somewhat lengthy , but would be thankful if you could provide me some assitance with the above mentioned answers.even hints will work.


            Regards

            Ankan

            • 3. Re: Regarding terminator wizard
              Steve_McKinney

              ankan wrote:

               

              Hi Steve


              Thanks for your reply.I got your point ,however still have some doubts in my mind if you can clear that.


              1)The transmission line parameters like the impedance and rise time values are loaded when the stack up is enetered as we can also edit the Tx line parameters like (TL1 And TL2 in your case),but how can we know the exact impedances and timing values for these Tx lines?


              Yyou can see in my schematic that it tells you the exact impedance and propagation delay of the transmission lines.  This is derived from the stackup that you have in LineSim (just like it is done in BoardSim).  You also have the liberty to enter exact impedances and delays in a simple transmission line if you want.

               

               

               

              2)Can we load the IBIS models for the driver and receivers and can take the respective pins into account while simulating through linesim?

              Yes, you can do that. You can load IBIS models, SPICE models, and S-parameter models here to create a true representation of your design which you can develop your routing rules from.

               

              3)In case of differential Tx lines, can we simulate and find the differential termination resistances in linesim ?

              Yes, you can do that as well as long as it's a parallel differential termination

              .diff_term.pngdiff_term_wizard.png


              I think this questionairre has become somewhat lengthy , but would be thankful if you could provide me some assitance with the above mentioned answers.even hints will work.


              Regards

              Ankan

              • 4. Re: Regarding terminator wizard
                ankan

                Hi Steve

                 

                Thanks for your replies and am grateful to you that the answers provided were on to the point and notable.

                 

                As far as  this differential termination is concerned, you wrote that unless the termination is parallel we can't simulate the same in Hyperlynx.

                However if we treat the individual Tx lines in differential signals as single ended and simulate .Can we obtain some viable results or do you think that it will be off from the logic.

                 

                What do you suggest on this?Do we have to always follow the parallel termination for differential signals or we can use series one as far as simulation on Hyperlynx is concerned?

                 

                It would be great if you could reply to this last question of this thread.

                 

                 

                Regards

                Ankan

                • 5. Re: Regarding terminator wizard
                  Steve_McKinney

                  You can use series terminators, but they aren't very common on differential signals.  Usually, a series resistor is too much of an attenuator to be a viable option on a differential pair because you are typically dealing with fast switching signals. 

                   

                  For your  diff pairs, my suggestion would be to use the Sweeps Manager in LineSim instead of the terminator wizard.  If you use the sweeps, you can set different values for your series or parallel components and find the best combination of terminator values based on the waveform quality you're looking for.  This will be must more reliable and faster than trying to manipulate net structures so they work in the terminator wizard to get the terminator values. 

                   

                  -Steve

                  • 6. Re: Regarding terminator wizard
                    agxinmj

                    Hai

                          In the above discussion you said that the impedance is calculated from the stack up ,I have a scenario consider a ddr3 data bus using sstl logic of 1,5 volts ,the reference plane of ddr should  be its own power plane or ground plane if some other supply plane is placed in the above or below layer of the ddr data signal the supply noise in the plane get coupled to the signal which you can practically realize,how to find the effect of noisy power planes below or above ddr data lines while simulating  ?due to increase in the length of the return current path.